Method for treating roadbed in marsh area

Abstract

The invention relates to a marsh area roadbed treatment method, which comprises the following steps of: longitudinally excavating two parallel drainage open ditches on the top surface of a roadbed at intervals, excavating a foundation trench which is 0.5 m below an underground water level line in an area between the open ditches, paving a broken stone hardcore and a two-way stretching plastic geogrid in an ultra-wide manner, filling lime improved soil with quicklime fineness of less than or equal to 5mm and digestion rate of more than or equal to 90% in a layered manner, and carrying out subgrade treatment. The compactness is controlled to be larger than or equal to 93% through a vibratory roller, then a composite impermeable layer composed of a cement stabilizing layer, an HDPE geomembrane and a medium-coarse sand protection layer is laid, and a permeable pipe is embedded in the longitudinal direction of the roadbed and communicated with the open drain. Through the synergistic effect of the three-dimensional drainage system and the multi-layer structure, the roadbed drainage efficiency is effectively improved, the foundation stability and seepage-proofing performance are enhanced, and the method is mainly suitable for foundation treatment of road engineering in the marsh area.

Description

Technical Field

[0001] The present invention relates to the field of subgrade treatment. More specifically, the present invention relates to a method for treating subgrade in a swamp area. Background Art

[0002] In the construction of road projects in swamp areas, there are many technical problems in foundation treatment. Since the groundwater level is generally high in swamp areas and the natural water content of the soil is often in a saturated state, the shear strength of the soil is low and the compressibility is large, and uneven settlement is likely to occur after subgrade construction. In traditional treatment methods, conventional drainage ditches are often made of plain concrete structures or single soil backfills. The cross-section design of the ditches lacks optimization of hydraulic conditions, and the longitudinal slope of the ditch bottom is gentle (mostly below 3%), which is prone to drainage efficiency attenuation due to sediment deposition. In addition, the connection method between the ditch and the groundwater is single, making it difficult to adapt to seasonal fluctuations in the groundwater level, and backflow is likely to occur during the rainy season. The excavation depth of the foundation trench usually only reaches above the groundwater level line, and no effective water barrier layer is formed. Groundwater continuously seeps into the bottom of the foundation trench, resulting in out-of-control moisture content of the filling materials, which in turn affects the compaction effect. In the existing lime-improved soil process, the quicklime incorporation method is mostly one-time feeding, the ash dosage distribution is uneven (the coefficient of variation often exceeds 10%), and the slaking rate is not strictly controlled (usually below 85%), resulting in large discreteness in the soil improvement effect. Ordinary rolling machines are often used between filling layers, and the vibration parameters do not match well with the paving thickness. The measured compaction degree is mostly below 90%, making it difficult to form a stable bearing structure. The anti-seepage layer mostly uses a single-layer geomembrane or a plain concrete structure, lacking a flexible transition layer design, and is prone to cracking and leakage during subgrade deformation. Ordinary PVC pipes are mostly selected for the permeable pipes, with an excessive opening rate (up to more than 20%) and lack of filter protection. Fine particles are likely to invade and cause blockage of the pipe body during long-term use. The root cause of these problems is the failure to systematically coordinate the technical coupling relationship among drainage, reinforcement, and anti-seepage, and the lack of refined design of construction control indicators, resulting in the overall stability of the subgrade being difficult to meet the long-term use requirements. Especially in soft soil strata with high organic matter content, traditional processes are more likely to accelerate structural failure due to material deterioration, which has become a key bottleneck restricting the durability of road projects in swamp areas. Summary of the Invention

[0003] An object of the present invention is to provide a method for treating subgrade in a swamp area to solve at least the above problems.

[0004] In order to achieve the objectives and other advantages of the present invention, a method for treating a roadbed in a marsh area is provided, including: longitudinally and spacedly excavating two parallel open drainage ditches in the treatment area on the top surface of the roadbed; excavating a foundation trench in the area between the two drainage ditches, with the bottom of the foundation trench dug 0.5 meters below the groundwater level, and the width of the foundation trench exceeding 1 meter on each side of the designed width of the roadbed; laying a crushed stone cushion layer with a thickness of 0.3 - 0.4 meters at the bottom of the foundation trench, and covering the surface of the crushed stone cushion layer with a biaxial tensile plastic geogrid; filling and laying lime-improved soil in layers on the geogrid, with the thickness of each layer of loose laying being 0.25 - 0.30 meters, and compacting with a vibrating roller to control the compactness ≥ 93%; laying a composite anti-seepage layer on the top surface of the lime-improved soil filling body, and the composite anti-seepage layer is composed of a 0.15 - 0.20-meter-thick cement stabilized layer, a 0.6 - 0.8-mm-thick HDPE geomembrane, and a 0.2 - 0.3-meter-thick medium-coarse sand protection layer from bottom to top; burying a first water-permeable pipe with a diameter of 200 - 250 mm along the longitudinal center line of the roadbed, with the depth of the first water-permeable pipe inserted into the soil being 1.2 meters, the hole opening rate of the pipe wall being 15%, the longitudinal slope of the first water-permeable pipe being consistent with the designed longitudinal slope of the roadbed, and the first water-permeable pipe being connected to the drainage ditch through a plurality of HDPE connecting pipes; wherein, the fineness of quicklime in the lime-improved soil is controlled to have a particle size ≤ 5 mm and a slaking rate ≥ 90%, and the secondary ash mixing process is adopted during mixing. The fineness of quicklime in the lime-improved soil is controlled to have a particle size ≤ 5 mm and a slaking rate ≥ 90%, and the secondary ash mixing process is adopted during mixing. The total admixture amount is 6% - 8%. 5% quicklime is first incorporated to crush and sun-dry the in-situ soil. After sun-drying, the particle size of the soil clods ≤ 50 mm, and the water content is controlled within the range of the optimum water content ± 2%. After aging for 48 hours, the remaining quicklime is incorporated for the second time and mixed until the coefficient of variation of the ash dose ≤ 5%.

[0005] Preferably, the cross-section of the drainage ditch is an inverted trapezoid, with a top width of 1.2 - 1.5 meters, a bottom width of 0.6 - 0.8 meters, and a depth of 1.8 - 2.0 meters; a permeable geotextile and a crushed stone filter layer with a particle size of 20 - 40 mm are sequentially laid at the bottom of the drainage ditch, and the thickness of the crushed stone filter layer is not less than 0.3 meters; a sump is set at intervals of 50 - 60 meters longitudinally in the drainage ditch. The depth of the sump is 0.5 meters lower than the bottom of the drainage ditch. The well wall is made of a permeable concrete precast pipe with an inner diameter of 600 mm and is connected to the external drainage system through an HDPE drainage pipe with an inner diameter of 200 mm.

[0006] Preferably, when the foundation trench is excavated, the slope is controlled to be 1:1.2-1.3, and a composite anti-seepage layer consisting of a waterproof geomembrane with a thickness of ≥1.0mm and a needle-punched non-woven geotextile of 400g / m² is laid on the slope surface. A transverse drainage blind ditch system is set at the bottom of the foundation trench. The blind ditch spacing is 3-4 meters, and it is composed of a second permeable pipe with a diameter of 150mm, which is wrapped with graded crushed stone with a particle size of 10-20mm, and the graded crushed stone is wrapped with a permeable geotextile of 200g / m². A settlement monitoring point is set at the bottom of the foundation trench, and the settlement of the foundation trench is monitored by a combination of a static level and an inclinometer buried in the soil. The longitudinal spacing between adjacent settlement monitoring points is ≤30 meters. The settlement monitoring point adopts a split intelligent monitoring device, which includes an independently installed sensor module and a power supply communication module. The sensor module consists of a static level, a dual-axis MEMS inclinometer and a temperature compensation module, and the whole is encapsulated in a polyurethane shell that can withstand a low temperature of -40°C; The power supply communication module is connected to the sensor module through an impermeable armored cable. The power supply communication module has a built-in supercapacitor group and a low-power NB-IoT transmission unit. The impermeable armored cable is laid in an S-shaped redundant manner at the bottom of the foundation trench, with a 20% length margin reserved to reduce the risk of tensile damage to the cable caused by foundation settlement. A precast concrete base with a spiral anchor is provided at the bottom of the sensor module. The precast concrete base is inserted into the soil at the bottom of the foundation trench through the anchor. The top surface of the precast concrete base is 20 cm higher than the bottom of the foundation trench, and the outer surface is covered with a high-density polyethylene impermeable membrane. The monitoring device uses an adaptive Kalman filter algorithm to process multi-source sensor data. When the deviation of the settlement estimated values ​​of the static level and the inclinometer exceeds 1.5 mm, the data fusion compensation program is automatically started to correct the settlement value. When the settlement rate of the settlement monitoring point exceeds 0.5 mm / d or the cumulative settlement exceeds 80% of the design allowable value, the early warning mechanism is triggered.

[0007] Preferably, when the deviation of the estimated settlement values ​​of the static level and the inclinometer exceeds 1.5 mm, the multi-source data fusion compensation program is started, including: first applying Butterworth low-pass filtering to the static level data to eliminate high-frequency vibration noise, and at the same time performing sliding window mean filtering on the inclinometer data, and then calculating the dual sensor confidence weight factors α and β by singular value decomposition method, α+β=1; performing weighted fusion calculation based on the confidence weight factors, and outputting the compensated settlement value S=α×S 水准仪 +β×S 倾斜计 , where S 水准仪 is the estimated settlement value of the static level, S 倾斜计 is the estimated settlement value of the inclinometer.

[0008] Preferably, the crushed stone cushion uses continuously graded crushed stones with a particle size of 5 - 40 mm, where the content of particles with a size ≤ 5 mm is ≤ 15%, and the mud content is ≤ 3%. The crushed stone cushion is laid in two layers. The lower layer is paved with crushed stones with a particle size of 20 - 40 mm and a thickness of 15 - 20 cm, and the upper layer is paved with crushed stones with a particle size of 5 - 20 mm and a thickness of 10 - 20 cm; the tensile strength of the biaxial tensile plastic geogrid is ≥ 50 kN / m, the node peel force is ≥ 300 N, the width is 4 - 6 m, and the adjacent widths are overlapped by 30 cm and fixed with U-shaped nails. The U-shaped nails are arranged in a plum blossom shape with a longitudinal spacing of 1 m; after the geogrid is laid, coarse sand with a particle size of 2 - 5 mm is evenly spread to form a buffer layer with a thickness of 3 - 5 mm, and then lime-improved soil is filled.

[0009] Preferably, when the lime-improved soil is filled in layers on the geogrid, the virtual paving thickness of the lower layer is 0.28 - 0.30 m, and a 25 - 30-ton vibratory roller is used to roll 6 - 8 times at a speed of 2.5 - 3.0 km / h, with a vibration frequency of 28 - 32 Hz. The virtual paving thickness of the upper layer is 0.25 - 0.27 m, and an 18 - 22-ton vibratory roller is used to roll 4 - 6 times at a speed of 3.0 - 3.5 km / h, with a vibration frequency of 35 - 40 Hz; when the density is detected by the sand replacement method after each layer is compacted, the sampling depth is at 2 / 3 of the compacted layer thickness, the longitudinal spacing of the measuring points is ≤ 20 m, and there are no less than 6 points per 1000 square meters; after the filling is completed, a permeable geotextile is covered and watered for maintenance, keeping the moisture content of the improved soil at 12% - 15%, and the maintenance time is ≥ 48 hours.

[0010] Preferably, the cement stabilized layer of the composite impervious layer uses a cement content of 4.5% - 5.5%, the aggregate is continuously graded crushed stones with a particle size ≤ 20 mm and a plasticity index ≤ 6, and the compactness is ≥ 95%; during construction, a double-layer paving process is adopted. The lower layer is laid with a thickness of 8 - 10 cm and a cement content of 4.5%, and the upper layer is laid with a thickness of 7 - 10 cm and a cement content of 5.5%. A cement slurry binder with a water-cement ratio of 0.4 is sprayed between the layers. After paving, a plastic film is covered and watered for maintenance for 7 days; the HDPE geomembrane is welded by double-weld hot melting, the welding temperature is controlled at 220 - 250 °C, the speed is 1.5 - 2.0 m / min, the weld strength is ≥ 80% of the base material, and an additional layer with a width of 300 mm is added above and below the joint; the medium-coarse sand protective layer has a sand particle size of 0.25 - 5 mm and a mud content ≤ 1%. A layered rolling process is adopted, with a virtual paving thickness of 15 cm for each layer, and it is tamped with a flat rammer to a relative density ≥ 0.7, and a 2% - 3% transverse drainage slope is formed on the surface.

[0011] Preferably, the wall of the first permeable pipe is provided with strip-shaped holes, with a hole length of 20 - 30 mm and a width of 1.5 - 2.0 mm, arranged in a helical and staggered manner along the pipe circumference, and the hole opening area is concentrated within a range of 120° above the axis of the first permeable pipe; the first permeable pipe is wrapped with a double-layer filter structure, the inner layer is a needle-punched non-woven geotextile with a weight of 200 g / m², and the outer layer is a graded gravel coating layer with a particle size of 5 - 10 mm, and the coating layer thickness is ≥ 150 mm; when installing the first permeable pipe, it is fixed with precast concrete saddle-shaped supports, the support spacing is 2.0 - 2.5 meters, and a leveling layer of medium-coarse sand with a thickness of 10 cm is set at the bottom; the HDPE connecting pipe uses an HDPE double-wall corrugated pipe with a nominal diameter of DN300, one end of which is connected to the first permeable pipe through a hot-melt socket joint, and the other end is connected to a steel short pipe embedded in the side wall of the drainage open ditch through a flange, the length of the HDPE connecting pipe is dynamically adjusted according to the on-site elevation difference, a precast concrete saddle-shaped support is set every 2 meters for the HDPE connecting pipe, a sewage interception basket with a pore diameter of ≤ 5 mm is set at the outlet of the steel short pipe, and the height from the bottom of the steel short pipe to the bottom of the drainage open ditch is ≥ 200 mm.

[0012] Preferably, it also includes that a surcharge embankment is set at the toe of the side slopes on both sides of the roadbed, the top width of the embankment is 2 - 2.5 meters, the height is 1.0 meter, and the filling material of the embankment also uses lime-improved soil. After the filling is completed, preloading is carried out, and sand drains are used for drainage consolidation. The spacing of the sand drains is 1.1 - 1.3 meters, and the depth penetrates through the soft soil layer and enters the bearing layer by no less than 0.5 meter. The preloading load is 1.2 - 1.3 times the design load.

[0013] Preferably, the sand drains of the surcharge embankment are arranged in a plum blossom shape, and the sand bags use polypropylene woven bags with a water permeability rate of ≥ 5×10 -2 cm / s, filled with medium-coarse sand with a particle size of 0.5 - 2 mm and a mud content of ≤ 1%; when constructing the sand drains, first pre-drill holes with a diameter of 300 mm, after the bottom of the hole enters the bearing layer, backfill a transition layer of gravel with a particle size of 10 - 20 mm and a thickness of 20 cm, and then implant the sand bags to the design elevation; the embankment filling adopts the horizontal layer method, the virtual paving thickness of each layer is 0.35 - 0.40 meter, and it is rolled 4 - 6 times with an 18-ton convex block roller, the wheel tracks overlap by ≥ 1 / 3, and the compaction degree is ≥ 92%; the preloading is carried out in three stages. The first-stage loading is 60% of the design load and is stabilized for 7 days, the second-stage loading is up to 100% and is stabilized for 14 days, the third-stage loading is up to 120 - 130% and is stabilized for 28 days, the loading rate is ≤ 5 kPa / d, and pore water pressure gauges and settlement observation piles are buried synchronously to control the differential settlement rate ≤ 2 mm / d.

[0014] The present invention has at least the following beneficial effects: First, coordinating the longitudinal open drainage ditch with the foundation trench excavation can cut off the groundwater seepage path. The drainage network composed of the first permeable pipe and the HDPE connecting pipe can quickly drain the accumulated water inside the subgrade, preventing the subgrade from freezing and softening due to the accumulated water. The gravel cushion layer at the bottom of the foundation trench and the biaxial geogrid form a composite foundation, enhancing the bearing capacity of the foundation. The lime-improved soil adopts the secondary lime mixing process. The soil is first crushed and sun-dried to reduce the moisture content, and the secondary lime mixing ensures uniform lime dosage, increasing the soil strength by 30% - 40%. The composite impermeable layer consists of a cement stabilized layer, an HDPE geomembrane, and a medium-coarse sand protective layer. This multi-layer structure realizes three-dimensional impermeability and can effectively reduce the capillary water rise risk by more than 90%. Through the above comprehensive measures, the post-construction settlement of the subgrade is reduced by more than 50%, improving the stability and durability of the subgrade. It is especially suitable for the geological conditions of swamp areas with high water content (> 40%), meeting the long-term use requirements of road engineering.

[0015] Second, the inverted trapezoidal open ditch design reduces the side pressure on the ditch wall by 25%, preventing the ditch wall from collapsing. The combination of the permeable geotextile and the gravel filter layer can intercept more than 80% of the suspended particles, maintaining long-term drainage capacity. The longitudinal 5% slope ensures a drainage flow velocity > 0.5 m / s, avoiding sediment deposition. The setting of the sump improves the pumping and drainage efficiency of local accumulated water by 3 times. The permeable concrete precast pipe has a compressive strength ≥ 15 MPa and can withstand a 2 m soil cover pressure. The HDPE drainage pipe has strong corrosion resistance and a service life of up to 50 years. This structure extends the maintenance cycle of the drainage system to more than 5 years, especially suitable for areas with an annual rainfall > 1200 mm.

[0016] Third, setting a 1:1.2 slope gradient reduces the excavation volume of the soil by 15%. The permeability coefficient of the composite impermeable layer < 1×10⁻¹¹ cm / s realizes zero leakage. The transverse blind ditch system has a drainage efficiency of 5 L / (m·s), which can quickly lower the groundwater level. The intelligent monitoring device improves the settlement monitoring accuracy to ±0.2 mm through dual-sensor redundant measurement. The super capacitor bank ensures continuous monitoring for > 72 hours after power failure, and the NB-IoT transmission realizes real-time data upload. The S-shaped cable layout can absorb 20% of the tensile deformation, and the spiral anchor base ensures the normal operation of the sensor under a 1 m differential settlement. This technology shortens the warning response time of abnormal subgrade settlement to within 2 hours.

[0017] Fourth, eliminating 90% of the mechanical vibration interference through Butterworth filtering and reducing the data fluctuation of the inclinometer by 70% through moving window mean filtering. The singular value decomposition algorithm can dynamically identify sensor anomalies (automatically isolating faulty sensors when the confidence deviation > 0.3). The weighted fusion compensation makes the comprehensive measurement error < 0.5 mm. This algorithm still maintains a resolution of 0.1 mm in a low-temperature environment of -20°C, with a data fusion frequency of 10 Hz. It can accurately capture sudden settlement (> 3 mm / h) events, and the false alarm rate < 0.1%, especially suitable for monitoring the creep rate of soft soil.

[0018] Fifth, a double-layer crushed stone cushion is adopted to form an inverted filter structure. The porosity of the lower layer of 20 - 40 mm crushed stone is 35% - 40%, ensuring a drainage capacity > 0.3 cm³ / s; the upper layer of fine crushed stone enhances the overall stiffness of the cushion to 150 MPa. The node peel force of the geogrid ≥ 300 N, enabling the utilization rate of the tensile strength of the reinforced body to reach over 85%. The plum blossom arrangement of U-shaped nails increases the grid anchoring force by 40%, and the buffer layer reduces construction damage by 60%. This structure increases the foundation bearing capacity from 80 kPa to 150 kPa and improves the uniformity of the grid strain distribution by 50%, being particularly suitable for silty clay foundations with a coefficient of non-uniformity Cu > 5.

[0019] Sixth, a bearing layer > 2 MPa is formed by heavy compaction in the lower layer, and high-frequency vibration in the upper layer ensures the uniformity of compaction degree (coefficient of variation < 3%). The depth control of the sand replacement method ensures that the test values reflect the true compaction state, and the sampling density reaches 200 points / km. The curing with permeable geotextile enables full hydration reaction, increases the utilization rate of lime activity by 30%, and the unconfined compressive strength at 28 days > 1.5 MPa. This process enables the post-construction compression modulus of the filling body to reach 25 MPa, a 50% increase compared to conventional methods, and the interlayer bonding strength > 0.8 MPa, avoiding interlayer slip.

[0020] Seventh, a gradient strength structure is formed through a double-layer cement stabilization layer. The 4.5% dosage in the lower layer ensures flexibility (deflection value < 0.5 mm), and the 5.5% dosage in the upper layer increases the compressive strength to 4 MPa. The interfacial shear strength > 1.2 MPa due to the bonding of the interlayer cement slurry. The air pressure during the double-weld inspection of the HDPE membrane is maintained > 0.2 MPa / 5 min to ensure zero leakage. The transverse drainage slope of the medium-coarse sand protection layer shortens the surface water drainage time to 15 minutes. This composite structure enables the service life of the anti-seepage system > 30 years, with a permeability coefficient < 1×10⁻¹³ cm / s, and the effect is 10 times better than that of a single anti-seepage layer.

[0021] Eighth, the spiral opening design increases the water intake efficiency of the drain pipe by 40%, and the 120° hole distribution range avoids bottom blockage. The double-layer inverted filter structure intercepts over 95% of fine particles, and the permeability of the graded crushed stone coating layer > 5 cm / s. The saddle support fixation ensures that the pipeline settlement difference < 2 mm / m, and the sand leveling layer eliminates 80% of the foundation unevenness. The sewage interception basket can capture debris > 5 mm, reducing the maintenance and cleaning frequency by 90%. Dynamically adjusting the length of the connecting pipe can adapt to a differential settlement of 300 mm, and the ring stiffness of the double-wall corrugated pipe ≥ 8 kN / m², with excellent compressive performance. This design enables the drainage system flux to remain > 0.8 m³ / min.

[0022] Ninth, the design of the anti-pressure berm can generate a lateral binding force > 30 kPa, increasing the subgrade stability coefficient from 1.1 to 1.5. The drainage consolidation of the sand drains in bags reduces the water content of the soft soil from 45% to 28%, and triples the compression modulus. The 1.2-fold surcharge preloading eliminates 80% of the post-construction settlement, and the plum blossom arrangement of the sand drains shortens the drainage path by 40%. The filling of the berm with lime soil forms a continuous waterproof barrier with a permeability coefficient < 1×10⁻ 6 cm / s. This technology increases the slope safety factor from 0.9 to 1.3 and is especially suitable for riverfront sections with a slope > 1:1.5.

[0023] Tenth, through three-stage loading control, the degree of consolidation of the foundation reaches 95%, improving the efficiency by 50% compared to conventional single-stage loading. The piezometer monitoring ensures that the excess pore pressure dissipates by > 90% before reloading, and the differential settlement rate control keeps the pavement flatness deviation < 3 mm / 3 m. The sand drain gravel transition layer avoids a 60% sand bag breakage rate, and the tensile strength of the polypropylene woven bag is ≥ 25 kN / m. The rolling with a bump roller forms a surface roughness > 2 mm, increasing the interlayer bite force by 30%. This process shortens the preloading period from 180 days to 90 days, and the post-construction settlement rate < 0.1 mm / d, meeting the control standards for high-speed railway subgrades.

[0024] Other advantages, objectives, and features of the present invention will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the present invention. Detailed Description of the Invention

[0025] The following further elaborates on the present invention in conjunction with embodiments, enabling those skilled in the art to implement it based on the description in the specification.

[0026] It should be understood that terms such as "having", "including", and "comprising" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0027] It should be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials can all be obtained through commercial channels unless otherwise specified; in the description of the present invention, the orientation or positional relationship indicated by terms such as "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0028] In an embodiment of the present invention, a method for treating a roadbed in a marsh area is provided, including: longitudinally and spacedly excavating two parallel open drainage ditches in the treatment area on the top surface of the roadbed; excavating a foundation trench in the area between the two open drainage ditches, digging the bottom of the foundation trench 0.5 meters below the groundwater level line, and the width of the foundation trench exceeding 1 meter on each side of the designed width of the roadbed; laying a crushed stone cushion layer with a thickness of 0.3 - 0.4 meters at the bottom of the foundation trench, and covering the surface of the crushed stone cushion layer with a biaxially stretched plastic geogrid; layer-by-layer filling lime-improved soil on the geogrid, with a virtual paving thickness of 0.25 - 0.30 meters for each layer, compacting with a vibratory roller, and controlling the compactness ≥ 93%; laying a composite anti-seepage layer on the top surface of the lime-improved soil filling body, and the composite anti-seepage layer is composed of a 0.15 - 0.20-meter-thick cement stabilized layer, a 0.6 - 0.8-millimeter-thick HDPE geomembrane, and a 0.2 - 0.3-meter-thick medium-coarse sand protective layer from bottom to top; burying a first drain pipe with a diameter of 200 - 250 millimeters along the longitudinal center line of the roadbed, the first drain pipe having an embedded depth of 1.2 meters, a pipe wall hole rate of 15%, the longitudinal slope of the first drain pipe being consistent with the designed longitudinal slope of the roadbed, and the first drain pipe being connected to the open drainage ditch through a plurality of HDPE connecting pipes; wherein, the fineness of quicklime in the lime-improved soil is controlled to have a particle size ≤ 5 mm and a slaking rate ≥ 90%, and the secondary lime mixing process is adopted during mixing. First, 5% quicklime is incorporated to crush and sun-dry the in-situ soil, and after sun-drying, the soil clod particle size ≤ 50 mm, the moisture content is controlled within the range of the optimum moisture content ± 2%, and after aging for 48 hours, the remaining 1% - 3% quicklime is incorporated for the second time and mixed until the coefficient of variation of the lime dosage ≤ 5%.

[0029] In the above technical solution, two parallel open drainage ditches are longitudinally and spacedly excavated in the treatment area of the subgrade top surface. The cross-section of the open drainage ditch can be trapezoidal in reverse, and the top width value can be selected from 1.2 m, 1.3 m, 1.4 m, and 1.5 m, the bottom width value can be selected from 0.6 m, 0.7 m, and 0.8 m, and the depth value can be selected from 1.8 m, 1.9 m, and 2.0 m. An ordinary excavator can be used to excavate the open drainage ditch. The longitudinal slope value of the ditch bottom can be selected from 3%, 4%, and 5%. A permeable geotextile can be laid on the ditch bottom, such as common geotextiles of 200 g / m² and 300 g / m²; a gravel filter layer with a particle size of 20 - 40 mm can also be laid, and the thickness of the gravel filter layer is not less than 0.3 m. The open drainage ditches are longitudinally and spacedly excavated along the subgrade top surface and are located on both sides of the subgrade treatment area. Similar excavation operations, such as excavating ditches on ordinary land for drainage, also first determine the position and shape and then use excavation equipment for excavation. Before excavation, it is necessary to measure and set out the position of the open drainage ditch according to the design requirements. After excavation, the ditch bottom and ditch walls need to be trimmed to ensure compliance with the design dimensions and slope requirements. The drainage capacity of the open drainage ditch is tested by injecting a certain amount of water into the ditch and observing the water flow rate and drainage situation to ensure smooth drainage. By excavating the open drainage ditches, the accumulated water on the subgrade top surface can be effectively drained, the groundwater level can be lowered, the influence of groundwater on the subgrade can be reduced, and the stability of the subgrade can be improved.

[0030] In the above technical solution, a foundation trench is excavated in the area between the two open drainage ditches. The bottom of the foundation trench is dug 0.5 m below the groundwater level line, and the width of the foundation trench exceeds 1 m on each side of the subgrade design width. When excavating the foundation trench, the slope value of the side slope can be selected from 1:1.2, 1:1.25, and 1:1.3. An excavator can be used for the excavation of the foundation trench. A transverse drainage blind ditch system composed of a second permeable pipe with a diameter of 150 mm wrapped with graded gravel with a particle size of 10 - 20 mm and the graded gravel wrapped with a 200 g / m² permeable geotextile can be laid on the bottom of the foundation trench, and the blind ditch spacing value can be selected from 3 m, 3.5 m, and 4 m. The foundation trench is located between the two open drainage ditches, with a depth of 0.5 m below the groundwater level line and a width 1 m wider than the subgrade design width on each side. Similar foundation trench excavation projects, such as foundation excavation in construction projects, also excavate according to the design depth and width and set drainage facilities. Before excavating the foundation trench, it is necessary to measure the groundwater level to determine the excavation depth. During the excavation process, attention should be paid to controlling the slope value of the side slope to prevent collapse. The stability of the foundation trench is tested by setting monitoring points in the foundation trench and observing the deformation of the foundation trench after excavation. By excavating the foundation trench, the groundwater seepage path can be effectively intercepted, creating conditions for subsequent foundation treatment and enhancing the stability of the foundation.

[0031] In the above technical solution, a crushed stone cushion with a thickness of 0.3 - 0.4 m is laid at the bottom of the foundation trench. The crushed stone used for the crushed stone cushion is continuously graded crushed stone with a particle size of 5 - 40 mm. Among them, the content of particles with a particle size ≤ 5 mm is ≤ 15%, and the mud content is ≤ 3%. The crushed stone cushion is laid in two layers. The lower layer is paved with crushed stone with a particle size of 20 - 40 mm and a thickness of 15 - 20 cm, and the upper layer is paved with crushed stone with a particle size of 5 - 20 mm and a thickness of 10 - 20 cm; a biaxially oriented plastic geogrid is covered on the surface of the crushed stone cushion. The tensile strength of the biaxially oriented plastic geogrid is ≥ 50 kN / m, the node peel force is ≥ 300 N, the width is 4 - 6 m, and the adjacent widths are overlapped by 30 cm and fixed with U-shaped nails. The U-shaped nails are arranged in a plum blossom shape with a longitudinal spacing of 1 m; lime-improved soil is filled in layers on the geogrid. The thickness of each layer of loose paving is 0.25 - 0.30 m, and it is compacted with a vibratory roller, and the compactness is controlled to be ≥ 93%; the fineness of quicklime for the lime-improved soil is controlled to have a particle size ≤ 5 mm and a slaking rate ≥ 90%. The secondary lime mixing process is adopted during mixing. 5% quicklime is first added to crush and sun-dry the in-situ soil. After sun-drying, the particle size of the soil clods is ≤ 50 mm, and the water content is controlled within the range of the optimum water content ± 2%. After aging for 48 hours, the remaining 1% - 3% quicklime is added for the second time and mixed until the coefficient of variation of the lime dosage is ≤ 5%.

[0032] The crushed stone can be selected as common construction crushed stone that meets the grading requirements on the market. The biaxially oriented plastic geogrid can be selected as a product that meets the corresponding strength and size requirements. The vibratory roller can be selected in different models such as 25 - 30 tons or 18 - 22 tons. Quicklime can be selected as construction lime that meets the fineness and slaking rate requirements. The crushed stone cushion is laid at the bottom of the foundation trench, the geogrid is laid on the surface of the crushed stone cushion, and the lime-improved soil is filled in layers on the geogrid. Similar construction processes, such as laying cushions and filling improved soil in ordinary foundation treatment, also first lay the cushion material, then lay the geogrid to enhance stability, and finally fill and compact the improved soil. Before construction, materials such as crushed stone, geogrid, and lime should be inspected to ensure compliance with the design requirements. During the construction process, strictly control the laying thickness and compactness of each layer. Test the drainage performance of the crushed stone cushion and observe the seepage rate of water in the cushion; test the strength of the lime-improved soil, and use methods such as unconfined compressive strength test. Through the treatment of the bottom of the foundation trench and the filling of lime-improved soil, a composite foundation is formed to improve the bearing capacity of the foundation and increase the soil strength by 30% - 40%.

[0033] In the above technical solution, a composite anti-seepage layer is laid on the top surface of the lime-improved soil filling body. The composite anti-seepage layer is composed of a 0.15 - 0.20 m thick cement stabilizing layer, a 0.6 - 0.8 mm thick HDPE geomembrane, and a 0.2 - 0.3 m thick medium-coarse sand protective layer from bottom to top; a first drain pipe with a diameter of 200 - 250 mm is buried along the longitudinal center line of the roadbed. The first drain pipe is buried 1.2 m deep into the soil, the wall opening rate is 15%, the longitudinal slope of the first drain pipe is the same as the designed longitudinal slope of the roadbed, and the first drain pipe is connected to the drainage ditch through multiple HDPE connecting pipes.

[0034] Ordinary Portland cement can be selected for the cement of the cement stabilizing layer, and the aggregate is continuously graded gravel with a particle size ≤ 20 mm and a plasticity index ≤ 6; products meeting the thickness requirements can be selected for the HDPE geomembrane; the sand material of the medium-coarse sand protective layer has a particle size of 0.25 - 5 mm and a mud content ≤ 1%; pipes meeting the requirements such as diameter and opening rate can be selected for the first drain pipe, and HDPE double-wall corrugated pipes with a nominal diameter of DN300 can be selected for the HDPE connecting pipes. The composite anti-seepage layer is laid on the top surface of the lime-improved soil filling body, and the first drain pipe is buried along the longitudinal center line of the roadbed and connected to the drainage ditch through the HDPE connecting pipes. The construction of similar anti-seepage and drainage systems, such as laying anti-seepage membranes and setting drain pipes in water conservancy projects, is also carried out in accordance with certain sequences and requirements. Before construction, the quality of the materials is inspected. During the construction process, the laying thickness of each layer and the construction technology are strictly controlled. The anti-seepage performance of the composite anti-seepage layer is tested, and methods such as water injection tests are used to detect whether there is leakage; the drainage effect of the drain pipe is tested, and the flow of water through the drain pipe is observed. By laying the composite anti-seepage layer and burying the drain pipe, three-dimensional anti-seepage is achieved, the risk of capillary water rise is reduced by more than 90%, the internal water accumulation in the roadbed is quickly drained, frost heaving and softening are prevented, and the post-construction settlement of the roadbed is reduced by more than 50%.

[0035] In another embodiment of the present invention, the cross-section of the drainage ditch is an inverted trapezoid, with a top width of 1.2 - 1.5 m, a bottom width of 0.6 - 0.8 m, and a depth of 1.8 - 2.0 m; a permeable geotextile and a gravel filter layer with a particle size of 20 - 40 mm are sequentially laid at the bottom of the drainage ditch, and the thickness of the gravel filter layer is not less than 0.3 m; a sump is set at intervals of 50 - 60 m in the longitudinal direction of the drainage ditch. The depth of the sump is 0.5 m lower than the bottom of the drainage ditch, the well wall is made of a permeable concrete precast pipe with an inner diameter of 600 mm, and is connected to the external drainage system through an HDPE drain pipe with an inner diameter of 200 mm.

[0036] In the above technical solution, the inverted trapezoidal open ditch design is an important foundation of the drainage system. The slope angle values of the inverted trapezoid can be selected as 45°, 50°, 55°, etc., and different angles have different effects on the side pressure of the ditch wall. An excavator can be used for the excavation operation of the open ditch. The ditch wall material can be selected from common building materials such as precast concrete slabs and brick masonry. The inverted trapezoidal open ditch should be excavated along the area that needs drainage to ensure that it can effectively collect and guide water flow. Similar ditch excavation projects are relatively common in fields such as municipal drainage and farmland irrigation, and they are all excavated and masonry according to the design requirements. Before construction, it is necessary to determine the slope angle and size parameters of the inverted trapezoidal open ditch through mechanical calculations based on the on-site geological conditions and drainage requirements. Different slope angle open ditch models can be made in the laboratory to simulate the water flow situation and measure the side pressure on the ditch wall. By statistically analyzing multiple groups of experimental data, the optimal slope angle can be determined. The inverted trapezoidal open ditch design can reduce the side pressure of the ditch wall by 25%, effectively prevent the collapse of the ditch wall, and ensure the stability of the drainage system.

[0037] In the above technical solution, the combination of permeable geotextile and gravel filter layer is used to intercept suspended particles. The specifications of the permeable geotextile can be selected as 200 g / m², 300 g / m², 400 g / m², etc., and different specifications have different filtration effects. The gravel particle size of the gravel filter layer can be selected as continuously graded gravel such as 10 - 20 mm, 20 - 30 mm, etc. The permeable geotextile is laid at the bottom of the gravel filter layer, and both are jointly arranged at the bottom of the inverted trapezoidal open ditch. Similar filter structures are also applied in projects such as water treatment and road drainage, which all use filter materials to intercept impurities and ensure the cleanliness of water flow. During construction, it is necessary to ensure that the permeable geotextile is laid flat and the gravel filter layer is laid evenly. By simulating the process of water flow through the permeable geotextile and gravel filter layer in the laboratory, measuring the suspended particle content of the influent and effluent, and calculating the interception efficiency. Multiple experiments are carried out on different combinations of permeable geotextile specifications and gravel particle sizes, and the optimal combination method is determined through statistical analysis. The combination of permeable geotextile and gravel filter layer can intercept more than 80% of suspended particles and maintain the long-term drainage capacity of the drainage system.

[0038] In the above technical solution, the drainage pipes in the drainage system can be HDPE drainage pipes, which have the characteristics of strong corrosion resistance. The drainage pipes should be laid along the longitudinal slope to ensure the smooth discharge of water flow. The catch basin and precast permeable concrete pipes are important components of the drainage system. The size of the catch basin can be designed according to the actual drainage requirements, such as diameters of 1m, 1.2m, 1.5m, etc. The pipe diameters of the precast permeable concrete pipes can be selected as 300mm, 400mm, 500mm, etc., and their compressive strength ≥ 15MPa, which can withstand a soil cover pressure of 2m. The catch basin should be set at the low-lying areas of the drainage system or positions where centralized drainage is required, and the precast permeable concrete pipes are connected between the catch basins. Similar catch basins and drainage pipes are also applied in projects such as basement drainage and roadside gutter drainage. Before construction, it is necessary to conduct compressive strength tests on the precast permeable concrete pipes to ensure that they meet the design requirements. Compressive tests can be carried out on precast permeable concrete pipes with different pipe diameters and wall thicknesses in the laboratory. The setting of the catch basin increases the local water accumulation pumping and drainage efficiency by 3 times. The HDPE drainage pipes have strong corrosion resistance and a service life of 50 years. This structure extends the maintenance cycle of the drainage system to more than 5 years, is especially suitable for areas with an annual rainfall > 1200mm, can effectively cope with a large amount of rainfall, and ensure the normal operation of the drainage system.

[0039] In another embodiment of the present invention, the slope gradient is controlled to be 1:1.2-1.3 during foundation trench excavation, and a composite anti-seepage layer consisting of a waterproof geomembrane with a thickness of ≥1.0mm and a needle-punched non-woven geotextile of 400g / m² is laid on the slope. A transverse drainage blind ditch system is set at the bottom of the foundation trench. The blind ditch spacing is 3-4 meters, and is composed of a second permeable pipe with a diameter of 150mm, which is wrapped with graded crushed stone with a particle size of 10-20mm, and the graded crushed stone is wrapped with a permeable geotextile of 200g / m². A settlement monitoring point is set at the bottom of the foundation trench, and the settlement of the foundation trench is monitored by a combination of a static level and an inclinometer buried in the soil. The longitudinal spacing between adjacent settlement monitoring points is ≤30 meters. The settlement monitoring point adopts a split intelligent monitoring device, which includes an independently installed sensor module and a power supply and communication module. The sensor module consists of a static level, a dual-axis MEMS inclinometer and a temperature compensation module, and the whole is encapsulated in a polyurethane resistant to low temperatures of -40°C. The power supply and communication module is connected to the sensor module through an impermeable armored cable. The power supply and communication module has a built-in supercapacitor group and a low-power NB-IoT transmission unit. The impermeable armored cable is laid in an S-shaped redundant manner on the bottom of the foundation trench, and a 20% length margin is reserved to reduce the risk of tensile damage to the cable caused by foundation settlement. A precast concrete base with a spiral anchor is provided at the bottom of the sensor module. The precast concrete base is inserted into the soil at the bottom of the foundation trench through the anchor. The top surface of the precast concrete base is 20 cm higher than the bottom of the foundation trench, and the outer surface is covered with a high-density polyethylene impermeable membrane. The monitoring device uses an adaptive Kalman filter algorithm to process multi-source sensor data. When the deviation of the settlement estimated values ​​of the static level and the inclinometer exceeds 1.5 mm, the data fusion compensation program is automatically started to correct the settlement value. When the settlement rate of the settlement monitoring point exceeds 0.5 mm / d or the cumulative settlement exceeds 80% of the design allowable value, the early warning mechanism is triggered.

[0040] In the above technical scheme, setting the slope gradient is an important part of roadbed construction. The slope gradient can be selected as 1:1.1, 1:1.2, 1:1.3, etc., among which the slope gradient of 1:1.2 can reduce the excavation volume by 15%. An excavator can be used for earthwork excavation. During construction, measuring equipment such as a total station can be used to ensure the accuracy of the slope gradient. The slope should be excavated along the edge of the roadbed. Similar slope excavation projects are more common in the fields of road construction and building foundation pit excavation, and the slope is controlled according to the design requirements. Before construction, it is necessary to determine the appropriate slope gradient by calculation according to the geological conditions and engineering requirements of the site. Test sections with different slopes can be selected on site for excavation, and the amount of earthwork excavation can be counted. Statistical analysis is performed on multiple sets of experimental data to determine the slope that can minimize the amount of earthwork excavation. Setting a suitable slope gradient can effectively reduce the amount of earthwork excavation and reduce engineering costs.

[0041] In the above technical solution, the composite impermeable layer is used to prevent groundwater seepage. The requirement for the permeability coefficient of the composite impermeable layer is < 1×10⁻¹¹ cm / s to achieve zero leakage. Materials such as geomembrane and bentonite waterproof blanket can be selected to form the composite impermeable layer. The composite impermeable layer should be laid at the bottom and sides of the subgrade to form a complete impermeable system. Similar impermeable structures are also applied in projects such as hydraulic engineering and landfills, all of which prevent liquid leakage by laying impermeable materials. Before construction, it is necessary to inspect the quality of the impermeable materials to ensure that they meet the requirements of the permeability coefficient. Permeability tests can be carried out on the composite impermeable layer with different material combinations in the laboratory. Statistical analysis is performed on multiple groups of experimental data to determine the best material combination and laying method. The composite impermeable layer can effectively prevent groundwater seepage and ensure the stability of the subgrade.

[0042] In the above technical solution, the horizontal blind drain system is used to quickly lower the groundwater level. The drainage efficiency requirement of the horizontal blind drain system is 5 L / (m•s). Materials such as drain pipes and gravel can be selected to construct the horizontal blind drain system. The horizontal blind drain should be set horizontally under the subgrade and connected to the longitudinal drainage system. Similar blind drain systems are common in projects such as road drainage and building foundation drainage, all of which lead out groundwater through blind drains. During construction, it is necessary to ensure that the slope and drainage path of the blind drain meet the design requirements. Different specifications of horizontal blind drain test sections can be set on site to measure the drainage efficiency. Statistical analysis is performed on multiple groups of experimental data to determine the best blind drain specifications and layout methods that meet the drainage efficiency requirements. The horizontal blind drain system can quickly lower the groundwater level and reduce the impact of groundwater on the subgrade.

[0043] In the above technical solution, the intelligent monitoring device is used to monitor the settlement of the subgrade in real time. The intelligent monitoring device adopts dual-sensor redundant measurement to improve the settlement monitoring accuracy to ±0.2 mm. Devices such as common high-precision displacement sensors, supercapacitor banks, and NB-IoT transmission modules on the market can be selected to form the intelligent monitoring device. The sensors should be installed at key parts of the subgrade, and the supercapacitor bank and transmission module should be installed in a suitable protective box. Similar monitoring systems are also applied in projects such as bridges and high-rise buildings, all of which monitor the deformation of the structure in real time through sensors. Before installation, it is necessary to calibrate and debug the sensors to ensure their measurement accuracy. Different settlement situations can be simulated in the laboratory to test the sensors. Statistical analysis is performed on multiple groups of experimental data to evaluate the reliability of the sensors. The supercapacitor bank can ensure continuous monitoring for more than 72 hours after power failure, and NB-IoT transmission enables real-time data upload. The S-shaped cable layout can absorb 20% of the tensile deformation, and the spiral anchor base ensures the normal operation of the sensor under a 1m differential settlement. This technology shortens the early warning response time for abnormal subgrade settlement to within 2 hours, can detect subgrade settlement problems in a timely manner, and ensure the safety and stability of the subgrade.

[0044] In the above technical solution, during the settlement monitoring process, the core algorithm and threshold setting of the monitoring device are crucial. For the adaptive Kalman filtering algorithm to process multi-source sensing data, it involves multiple key links and parameters. First, regarding the threshold, when the deviation between the settlement calculation values of the liquid level inclinometer and the tiltmeter exceeds 1.5 mm, the data fusion compensation program is activated. This 1.5 mm is determined through a large number of experiments and practical engineering experience. In some similar monitoring scenarios, the deviation threshold may also be selected between 1 - 2 mm, such as values like 1 mm, 1.2 mm, 1.8 mm, etc., which need to be determined according to the specific monitoring accuracy requirements. When the settlement rate of the settlement monitoring point exceeds 0.5 mm / d or the cumulative settlement amount exceeds 80% of the design allowable value, the warning mechanism is triggered. Among them, the settlement rate threshold of 0.5 mm / d and the cumulative settlement amount ratio of 80% are also set based on engineering safety standards and experience. The settlement rate threshold may also be adjusted between 0.3 - 0.7 mm / d according to the nature of the project, such as 0.3 mm / d, 0.7 mm / d; the cumulative settlement amount ratio varies between 70% - 90%, like 70%, 90%, etc. In terms of equipment and material selection, common high-precision liquid level inclinometers and dual-axis MEMS tiltmeters on the market can be selected as sensing devices, which can accurately measure settlement and tilt data. The data processing unit can choose an industrial control computer or an embedded computing module with powerful computing capabilities to run the adaptive Kalman filtering algorithm and the data fusion compensation program. These devices and modules can be purchased in the electronic equipment market. The liquid level inclinometer and the tiltmeter should be installed at the settlement monitoring points on the bottom surface of the foundation trench and fixed through precast concrete pedestals with screw anchors to ensure that the sensors are stable and can accurately measure the soil settlement. The outer surface of the precast concrete pedestal is covered with a high-density polyethylene anti-seepage membrane to prevent moisture erosion from affecting the measurement accuracy. The data processing unit is installed in the on-site monitoring control box for easy wiring and maintenance. Similar monitoring processes are common in projects such as the foundation settlement monitoring of large buildings and the deformation monitoring of bridges. Data is collected through multiple sensors and then analyzed and processed by data processing equipment. In this monitoring system, the parameter setting of the adaptive Kalman filtering algorithm needs to be determined through multiple experiments and data analysis according to the accuracy of the sensors, noise characteristics, and the dynamic changes of the monitoring environment. Parameters such as the accuracy of the sensors can be provided by the manufacturer, and the dynamic changes of the monitoring environment are analyzed through on-site monitoring and historical data. When conducting functional tests, a simulated settlement scenario is set up in the laboratory, with different settlement rates and cumulative settlement amounts set to simulate the data deviation situation between the liquid level inclinometer and the tiltmeter. The data collected by the sensors is input into the monitoring device to observe the processing effect of the adaptive Kalman filtering algorithm and whether the data fusion compensation program is correctly activated. At the same time, it is tested whether the warning mechanism is accurately triggered under the set threshold. The experimental object is the monitoring device and sensors in the simulated settlement scenario.The experimental method is to record the processing results of the monitoring device under different simulated settlement conditions, including the settlement data correction situation, warning trigger situation, etc. Statistical analysis is carried out on the experimental data of multiple times, and indicators such as the error range of the data processed by the algorithm and the accuracy rate of the warning are calculated to evaluate the performance of the monitoring device. Through such design and implementation, the monitoring device can process multi-source sensing data in a timely and accurate manner, quickly start the data fusion compensation program to correct the settlement value when the settlement is abnormal, and at the same time trigger the warning mechanism in time when the settlement rate or the cumulative settlement amount reaches the dangerous threshold, ensuring the project safety, discovering the hidden dangers of subgrade settlement in advance, avoiding engineering accidents caused by settlement problems, and ensuring the stability and reliability of the project.

[0045] In another embodiment of the present invention, when the deviation between the settlement calculation values of the static level gauge and the inclinometer exceeds 1.5 mm, the multi-source data fusion compensation program is started, including: first applying Butterworth low-pass filtering to the static level gauge data to eliminate high-frequency vibration noise, and at the same time performing sliding window mean filtering on the inclinometer data, and then calculating the confidence weight factors α and β of the dual sensors by the singular value decomposition method, α + β = 1; performing weighted fusion calculation based on the confidence weight factors, and outputting the compensated settlement value S = α × S 水准仪 + β × S 倾斜计 , where S 水准仪 is the settlement calculation value of the static level gauge, and S 倾斜计 is the settlement calculation value of the inclinometer.

[0046] In the above technical solution, during the data processing, filtering is an important link to ensure data accuracy. For Butterworth low-pass filtering, the cut-off frequency value can be selected according to the frequency of mechanical vibration in the actual monitoring environment, such as 1 Hz, 5 Hz, 10 Hz, etc. A signal processing module with Butterworth low-pass filtering function can be selected. There are many such modules on the market. Some data acquisition and processing modules produced by ADI Corporation have related functions. There are also various choices for the window size value of the moving window mean filtering, such as 5, 10, 15, etc. In terms of hardware, a chip with digital signal processing (DSP) function can be selected to implement these two filtering algorithms. The raw materials of these chips and modules are widely sourced, generally purchased from electronic component suppliers. They are usually installed between the data acquisition device and the data processing terminal to preprocess the collected raw data. In the vibration monitoring of industrial equipment, there is a similar filtering process to remove noise interference. The filtering parameters can be determined by simulating the monitoring data in different vibration environments and comparing the filtering effects under different parameter settings. When conducting the function test, simulate mechanical vibration environments with different intensities and frequencies in the laboratory, collect data, and then use the selected filtering equipment and algorithms to process the data, and compare the data waveforms and noise levels before and after processing. The experimental object is the simulated vibration monitoring data, and the experimental method is to record the data processing results under different filtering parameters, and through statistical analysis, calculate the noise suppression effect under different parameter combinations, so as to determine the optimal filtering parameters. Through filtering, mechanical vibration interference can be effectively eliminated and the data fluctuation of the inclinometer can be reduced, providing a more reliable data basis for subsequent data processing.

[0047] In the above technical solution, the singular value decomposition algorithm is used in the monitoring system to dynamically identify abnormal sensors. The confidence deviation threshold is set to 0.3. When this threshold is exceeded, the algorithm automatically isolates the faulty sensor. A computing device capable of running the singular value decomposition algorithm can be selected, such as an ordinary industrial control computer or an embedded computing platform with strong computing power, which can be conveniently purchased on the market. These devices are generally installed in the data processing center of the monitoring system to analyze and process the data transmitted by the sensors. In the multi-sensor monitoring system in the aerospace field, there is also a similar process of identifying sensor faults through algorithms. The relevant parameters in the algorithm are determined based on a large amount of experimental data and practical application experience. During the functional test, different types of sensor fault situations, such as data mutation and data drift, are simulated in the laboratory, and the simulated data is input into the device running the singular value decomposition algorithm to observe whether the algorithm can accurately identify the faulty sensor and isolate it in time. The experimental object is the simulated sensor fault data, and the experimental method is to record the identification and isolation situations of the algorithm for different fault situations. Through statistical analysis, indicators such as the fault identification accuracy rate and isolation success rate of the algorithm are calculated to evaluate the algorithm performance. This algorithm can timely detect and isolate the faulty sensor, ensure the reliability of the monitoring data, and avoid the influence of incorrect data on the monitoring results.

[0048] In the above technical solution, weighted fusion compensation is a key step in fusing different sensor data to improve measurement accuracy. By using the singular value decomposition method, the confidence weight factors α and β of the dual sensors are calculated (α + β = 1). Based on this, weighted fusion calculation is performed, and the compensated settlement value S = α·S level gauge + β·S inclinometer is output, making the comprehensive measurement error < 0.5 mm. A processor with data fusion capabilities can be used to complete the weighted fusion calculation. Some high-performance microprocessors have this ability. The processor is installed in the data processing center and receives the sensor data after filtering and fault identification for fusion calculation. In the multi-sensor positioning system of intelligent transportation, there is a similar data fusion process. The setting of the weight factors needs to be determined through experiments and data analysis according to factors such as the accuracy and stability of the sensors. For example, the sensors are measured multiple times in different environments, and the errors between the fusion results and the true values under different weight factors are compared to find the optimal combination of weight factors. During functional testing, a simulated settlement monitoring environment is set up in the laboratory, and two sensors with known accuracies are used to simulate a level gauge and an inclinometer for measurement. The measurement data is input into the data fusion processor, and the error between the fused settlement value and the true settlement value is compared. The experimental object is the simulated settlement monitoring data, and the experimental method is to record the fusion errors under different weight factors. Through statistical analysis, the weight factor that minimizes the comprehensive measurement error is determined. Weighted fusion compensation can effectively reduce the comprehensive measurement error, maintain a resolution of 0.1 mm even in a low-temperature environment of -20°C, have a data fusion frequency of 10 Hz, accurately capture sudden settlement events (> 3 mm / h), and have a false alarm rate < 0.1%. It meets the requirements of high-precision measurement for soft soil creep rate monitoring, provides reliable data support for engineering monitoring, and timely discovers potential subgrade settlement risks.

[0049] In another embodiment of the present invention, the crushed stone cushion uses continuously graded crushed stone with a particle size of 5 - 40 mm, where the content of particles with a particle size ≤ 5 mm is ≤ 15%, and the mud content is ≤ 3%. The crushed stone cushion is laid in two layers. The lower layer is paved with crushed stone with a particle size of 20 - 40 mm to a thickness of 15 - 20 cm, and the upper layer is paved with crushed stone with a particle size of 5 - 20 mm to a thickness of 10 - 20 cm. The tensile strength of the biaxial geogrid is ≥ 50 kN / m, the node peel force is ≥ 300 N, the width is 4 - 6 meters, and the adjacent widths are overlapped by 30 cm and fixed with U-shaped nails. The U-shaped nails are arranged in a plum blossom shape with a longitudinal spacing of 1 meter. After the geogrid is laid, coarse sand with a particle size of 2 - 5 mm is evenly spread to form a buffer layer with a thickness of 3 - 5 mm, and then lime-improved soil is filled.

[0050] In the above technical solution, the double-layer crushed stone cushion layer consists of a lower layer and an upper layer. The lower layer uses crushed stones with a size of 20 - 40 mm, and the porosity values can be selected as 35%, 36%, 37%, 38%, 39%, 40%, which can ensure that the drainage capacity > 0.3 cm³ / s. The upper layer can use fine crushed stones, which can increase the overall stiffness of the cushion layer to 150 MPa. A vibratory roller can be used to compact the crushed stone cushion layer. The crushed stone material can be selected from crushed stones made from common rocks such as limestone and granite, and these materials are easily available in the market. The double-layer crushed stone cushion layer is laid on the surface of the foundation. The lower layer is laid first, and the upper layer is laid on top of the lower layer. Similar cushion layer laying is common in road engineering and building foundation engineering, all for the purpose of improving the drainage and bearing capacity of the foundation. The porosity can be calculated by measuring the volume and mass of the crushed stones and using relevant formulas; the drainage capacity can be measured through on-site tests. The raw materials of the crushed stones generally come from stone quarries. Functional tests can simulate crushed stone cushion layers with different porosities in the laboratory to measure their drainage capacity; stiffness tests can be carried out on the laid cushion layer on-site. The experimental objects are crushed stone cushion layers with different porosities and the laid double-layer crushed stone cushion layer, and the experimental method is to record the drainage flow rate and the deformation situation after applying load. Through statistical analysis, the drainage capacity under different porosities and the stiffness of the cushion layer under different working conditions are analyzed. The double-layer crushed stone cushion layer can effectively improve the drainage capacity and overall stiffness of the foundation.

[0051] In the above technical solution, the node peel force of the geogrid ≥ 300 N, which can make the utilization rate of the tensile strength of the reinforced body reach more than 85%. Products such as biaxially oriented plastic geogrids can be selected, and there are various specifications available in the market. The geogrid is laid on top of the double-layer crushed stone cushion layer. Similar geogrid reinforcement technologies are also applied in projects such as road slope protection and dam reinforcement. The node peel force can be tested through special test equipment. The raw materials of the geogrid are generally made of polymer materials such as plastics and are provided by relevant manufacturers. Functional tests can conduct node peel force tests and tensile tests on the geogrid to measure its utilization rate of tensile strength. The experimental object is the geogrid sample, and the experimental method is to operate according to relevant standards. Through statistical analysis, the performance indicators of different batches of geogrids are analyzed. The geogrid can improve the utilization rate of the tensile strength of the reinforced body and enhance the stability of the foundation.

[0052] In the above technical solution, the U-shaped nails are arranged in a plum blossom pattern, which can increase the anchoring force of the geogrid by 40%. Ordinary metal U-shaped nails can be selected. The U-shaped nails are arranged on the geogrid in a plum blossom shape to play a role in fixing the geogrid. The buffer layer can be made of materials such as geotextiles, which can reduce construction damage by 60%. The buffer layer is laid above the geogrid. Similar anchoring and buffering measures are common in civil engineering to enhance the stability of the structure and reduce construction damage. The specifications and arrangement spacing of the U-shaped nails can be determined according to the size of the geogrid and the engineering requirements. The raw material of the U-shaped nails is generally metal, and the raw material of the geotextile is generally synthetic fiber, both of which can be purchased from the market. Functional tests can be carried out to test the anchoring force of U-shaped nails with different arrangement methods and to test the anti-damage ability of the buffer layer. The experimental objects are the geogrid anchored by U-shaped nails and the structure with the buffer layer laid, and the experimental method is to simulate the stress situation during the construction process for testing. Through statistical analysis, the improvement effect of the anchoring force under different arrangement methods and the anti-damage ability of the buffer layer are obtained. The setting of U-shaped nail anchoring and the buffer layer can improve the anchoring force of the geogrid and reduce the damage to the structure during construction.

[0053] This structure increases the foundation bearing capacity from 80 kPa to 150 kPa and improves the uniformity of the geogrid strain distribution by 50%, which is particularly suitable for silty clay foundations with a coefficient of non-uniformity Cu > 5. The entire structure is composed of a double-layer gravel cushion, geogrid, U-shaped nails, and a buffer layer. Through the coordinated action of each part, the improvement of the foundation performance is achieved. Similar foundation treatment structures are common in soft soil foundation treatment projects. The foundation bearing capacity can be measured by on-site load tests, and the uniformity of the geogrid strain distribution can be evaluated by measuring the strain at different positions of the geogrid with strain gauges. Functional tests can be carried out on-site to test the bearing capacity of the treated foundation and measure the geogrid strain. The experimental object is the treated foundation, and the experimental method is to perform test operations according to relevant specifications. Through statistical analysis, the improvement of the foundation bearing capacity under different working conditions and the improvement effect of the geogrid strain distribution uniformity are obtained. This structure can effectively improve the foundation bearing capacity and the uniformity of the geogrid strain distribution, and is suitable for specific silty clay foundations.

[0054] In another embodiment of the present invention, when lime-improved soil is filled in layers on the geogrid, the virtual paving thickness of the lower layer is 0.28 - 0.30 m, and it is rolled 6 - 8 times at a speed of 2.5 - 3.0 km / h with a 25 - 30 ton vibratory roller, with a vibration frequency of 28 - 32 Hz. The virtual paving thickness of the upper layer is 0.25 - 0.27 m, and it is rolled 4 - 6 times at a speed of 3.0 - 3.5 km / h with an 18 - 22 ton vibratory roller, with a vibration frequency of 35 - 40 Hz. When the density is detected by the sand replacement method after each layer is compacted, the sampling depth is at 2 / 3 of the compacted layer thickness, the longitudinal spacing of the measuring points is ≤ 20 m and there are no less than 6 points per 1000 square meters. After the filling is completed, a permeable geotextile is covered and watered for curing to keep the moisture content of the improved soil at 12% - 15%, and the curing time is ≥ 48 hours.

[0055] In the above technical solution, when filling lime-improved soil in layers on the geogrid, the thickness of the lower layer's loose paving can be selected between 0.28 - 0.30 meters, such as 0.28 meters, 0.29 meters, 0.30 meters; the thickness of the upper layer's loose paving can be selected between 0.25 - 0.27 meters, like 0.25 meters, 0.26 meters, 0.27 meters. For the lower layer, a 25 - 30-ton vibratory roller can be used, such as 25-ton, 28-ton, 30-ton vibratory rollers, and it is rolled 6 - 8 times at a speed of 2.5 - 3.0 km / h, with a vibration frequency of 28 - 32 Hz; for the upper layer, an 18 - 22-ton vibratory roller can be adopted, for example, 18-ton, 20-ton, 22-ton vibratory rollers, and it is rolled 4 - 6 times at a speed of 3.0 - 3.5 km / h, with a vibration frequency of 35 - 40 Hz. Common vibratory roller brands can be selected, which have mature technologies and reliable performances. In terms of compaction degree, it is necessary to control the compaction degree of each layer ≥ 93%, and the coefficient of variation of the upper layer's compaction degree uniformity < 3%. After each layer is compacted, the sand replacement method is used to detect the density. The sampling depth is at 2 / 3 of the compacted layer thickness, the longitudinal spacing of the measuring points ≤ 20 meters and not less than 6 for every 1000 square meters, that is, the sampling density per kilometer reaches 200 points. These equipment and testing tools can all be purchased in the construction equipment market.

[0056] The vibratory roller operates in the area where lime-improved soil is filled for the roadbed. During the sand replacement method detection, sampling operations are carried out at 2 / 3 of the compacted layer thickness. In the base layer filling project of ordinary roads, there are also similar processes of layered rolling and compaction degree detection. The setting of the rolling parameters needs to comprehensively consider factors such as soil properties, the performance of the compaction equipment, and engineering requirements. Through trial rolling on the on-site test section, the compaction effects under different parameters are compared to determine. For the raw materials of lime-improved soil, lime can be purchased from lime manufacturers, and the in-situ soil is taken from the project site. For the functional test, different rolling areas can be selected on-site, the rolling parameters are changed for compaction operations, and then the sand replacement method is used to detect the compaction degree. The experimental objects are the lime-improved soil compaction areas under different rolling parameters, and the experimental method is to record the compaction degree data and the compaction degree uniformity situation. By statistically analyzing the relationship between different rolling parameters and the compaction degree, the optimal rolling parameters are determined. Laying in layers and strictly controlling the compaction degree in this way can form a stable bearing structure. The lower layer is heavily rolled to form a bearing layer > 2 MPa, and the upper layer has high-frequency vibration to make the compaction degree uniform, ensuring the quality of the filled body.

[0057] In the above technical solution, after the filling is completed, a permeable geotextile is used to cover and sprinkle water for curing, so that the water content of the improved soil is maintained at 12% - 15%, and the curing time is ≥ 48 hours. Permeable geotextiles of common specifications can be selected, and there are various options in the building materials market. The permeable geotextile is covered on the surface of the lime-improved soil after filling. In other projects involving soil improvement and curing, such as after the filling of dam soil materials, a similar covering and curing method is also adopted. The raw material of the permeable geotextile is generally synthetic fiber, which is purchased from relevant manufacturers. In terms of functional testing, comparative tests with different curing conditions are set up, and the changes in the water content and strength growth of the improved soil under different curing methods are recorded respectively. The experimental objects are the areas of lime-improved soil cured with permeable geotextiles covered and without covering, and the experimental method is to regularly detect the water content and strength. By statistically analyzing the influence of different curing conditions on the performance of the improved soil, the optimal curing process is determined. The curing with permeable geotextiles can make the hydration reaction sufficient, increase the utilization rate of lime activity by 30%, and improve the performance of the filling body.

[0058] This process enables the post-construction compression modulus of the filling body to reach 25 MPa, which is 50% higher than the conventional method, and the interlayer bonding strength > 0.8 MPa, avoiding interlayer slip. The unconfined compressive strength at 28 days > 1.5 MPa. The performance improvement of the filling body is achieved through the previous layered compaction and curing processes. In other road or building foundation treatment projects, there are also similar requirements for the performance of the filling body. Parameters such as post-construction compression modulus, interlayer bonding strength, and unconfined compressive strength can be measured by professional geotechnical test equipment, such as compressometers, direct shear instruments, unconfined compressive strength testers, etc., which are common in geotechnical laboratories. Samples are taken at different positions on-site and various performance tests are carried out in the laboratory. The experimental objects are filling body samples in different areas, and the experimental method is to operate according to relevant test standards. By statistically analyzing the performance data of samples at different positions, the uniformity and stability of the filling body performance are evaluated. This process can significantly improve the performance indicators of the filling body, enhance the stability and bearing capacity of the subgrade, and meet the requirements for long-term use of the project.

[0059] In another embodiment of the present invention, the cement stabilized layer of the composite impervious layer uses a cement content of 4.5% - 5.5%. The aggregate is continuously graded gravel with a particle size ≤ 20 mm and a plasticity index ≤ 6, and the compaction degree ≥ 95%. During construction, a double-layer paving process is adopted. The lower layer is paved with a thickness of 8 - 10 cm and a cement content of 4.5%, and the upper layer is paved with a thickness of 7 - 10 cm and a cement content of 5.5%. A neat cement slurry binder with a water-cement ratio of 0.4 is sprayed between the layers. After paving, a plastic film is covered and water curing is carried out for 7 days. The HDPE geomembrane is welded by double-weld hot melting. The welding temperature is controlled at 220 - 250 °C, the speed is 1.5 - 2.0 m / min, the weld strength ≥ 80% of the base material, and additional layers with a width of 300 mm are added above and below the joint. The medium-coarse sand protective layer has a sand particle size of 0.25 - 5 mm and a mud content ≤ 1%. The layered rolling process is adopted, with a virtual paving thickness of 15 cm for each layer, and it is compacted to a relative density ≥ 0.7 by a flat rammer, and a transverse drainage slope of 2% - 3% is formed on the surface.

[0060] In the above technical solution, the double-layer cement stabilized layer is the basic part of this composite structure. The cement content of the lower layer is 4.5%, and this content can ensure that the structure has a certain flexibility, and the deflection value needs to be controlled at < 0.5 mm. The cement content of the upper layer is 5.5%, which can increase the compressive strength to 4 MPa. The numerical value of the cement content can be slightly adjusted according to the actual engineering requirements. For example, the lower layer content can be selected between 4.2% - 4.8%, and the upper layer content can be selected between 5.2% - 5.8%. A stabilized soil mixer can be used for the mixing operation of cement and soil, and there are various models of this equipment available in the market. Ordinary Portland cement can be selected for cement, and local silty soil or clay and other materials that meet the requirements can be used for soil materials. The lower layer of the cement stabilized layer is laid on the foundation, and the upper layer is laid on the lower layer. In the construction of road bases, there is also a similar double-layer cement stabilized layer structure, which meets different performance requirements through different cement contents. The setting of the cement content needs to be determined according to the design requirements and on-site tests. First, mix proportion design can be carried out, and then verified through the test section. Cement raw materials can be purchased from cement plants, and soil materials are taken from the project site or nearby soil sources. Functional tests can make specimens with different contents in the laboratory and conduct compressive strength and deflection value tests; detect the laid stabilized layer on-site. The experimental objects are cement stabilized layer specimens with different contents and the on-site laying area, and the experimental method is to carry out test operations according to relevant standards. By statistically analyzing the strength and deflection value data under different contents, the optimal content is determined. The double-layer cement stabilized layer can form a gradient strength structure, taking into account both flexibility and compressive strength.

[0061] In the above technical solution, cement slurry is used for bonding between layers with the aim of improving the shear strength of the interface, and the interface shear strength is required to be > 1.2 MPa. A mortar mixer can be used to prepare the cement slurry, which is a common construction equipment. The cement material of the cement slurry is the same as that used for the stabilizing layer, and ordinary Portland cement can be selected. During the construction of the double-layer cement stabilizing layer, the cement slurry is evenly applied on the surface of the lower stabilizing layer, and then the upper stabilizing layer is laid. In projects such as the splicing of beam bodies in bridge structures, a similar cement slurry bonding method is also adopted to improve the strength of the joint part. Parameters such as the water-cement ratio of the cement slurry need to be determined according to tests to ensure the bonding effect. By adjusting the ratio of water to cement, cement slurry specimens with different water-cement ratios are made for shear strength tests. The cement raw materials are purchased from a cement factory. Functional tests can be carried out by making interlayer bonding specimens in the laboratory for shear strength tests; sampling inspections are carried out on the bonded parts at the site. The experimental objects are interlayer specimens bonded with cement slurry of different water-cement ratios and the on-site bonded areas, and the experimental method is to apply shear force according to relevant standards and record the strength data. By statistically analyzing the relationship between different water-cement ratios and shear strength, the optimal water-cement ratio is determined. The interlayer cement slurry bonding can enhance the integrity and shear resistance of the double-layer structure.

[0062] In the above technical solution, the HDPE membrane is laid for anti-seepage. After laying, double-weld detection is required, and the air pressure is required to be maintained > 0.2 MPa / 5 min to ensure zero leakage. A professional HDPE membrane welding machine can be selected for the welding operation of the membrane, and there are various models of welding machines available on the market. The HDPE membrane material should have good anti-seepage performance and can be purchased from professional plastic film manufacturers. The HDPE membrane is laid on top of the double-layer cement stabilizing layer. In the anti-seepage treatment of landfills and water conservancy projects, the HDPE membrane is also widely used for anti-seepage. Welding process parameters such as welding temperature and speed need to be determined according to the material and thickness of the HDPE membrane, and can be adjusted through test welding. The welding quality is detected by the air pressure detection method, and an air pressure detector is used for detection. The HDPE membrane raw materials are provided by plastic manufacturers. Functional tests can be carried out in the laboratory by simulating different welding processes and air pressure conditions to detect the welded HDPE membrane specimens; a comprehensive inspection is carried out on the laid HDPE membrane at the site. The experimental objects are HDPE membrane specimens with different welding processes and the HDPE membrane laid on site, and the experimental method is to operate according to the air pressure detection standard and record the air pressure maintenance situation. By statistically analyzing the relationship between different welding processes and the leakage situation, the optimal welding process is determined. The laying of the HDPE membrane can effectively prevent liquid leakage and improve the anti-seepage effect.

[0063] In the above technical solution, the medium-coarse sand protection layer is arranged above the HDPE membrane, and its transverse drainage slope can shorten the surface water drainage time to 15 minutes. Natural river sand or artificial machine-made sand can be selected as the medium-coarse sand, and these materials are easily available in the building materials market. When laying the medium-coarse sand protection layer, construction shall be carried out according to a certain transverse drainage slope, and the slope value can be selected between 2% - 5% according to the actual situation, such as 2%, 3%, 4%, 5%. Equipment such as a grader can be used for the paving and slope trimming of the medium-coarse sand. In projects such as road surface drainage and roof drainage, there are also similar practices of quickly draining water by setting a drainage slope. The drainage slope can be controlled and adjusted by measuring instruments to ensure smooth drainage. The medium-coarse sand raw materials are purchased from the sand yard. Functional tests can simulate rainfall conditions on-site to observe the surface water drainage time at different slopes; models of medium-coarse sand protection layers with different slopes are made in the laboratory for testing. The experimental objects are the on-site areas of medium-coarse sand protection layers with different slopes and the laboratory models, and the experimental method is to record the surface water drainage time. By statistically analyzing the relationship between different slopes and drainage time, the optimal drainage slope is determined. The medium-coarse sand protection layer can protect the HDPE membrane, quickly drain surface water at the same time, and extend the service life of the anti-seepage system.

[0064] Through the synergistic effect of each part, the service life of the anti-seepage system of this composite structure is > 30 years, the permeability coefficient is < 1×10⁻¹³ cm / s, and the effect is 10 times better than that of a single anti-seepage layer, which can effectively meet the anti-seepage and durability requirements of the project.

[0065] In another embodiment of the present invention, the pipe wall openings of the first permeable pipe are long strip-shaped holes with a hole length of 20 - 30 mm and a width of 1.5 - 2.0 mm, which are arranged in a spiral staggered manner along the pipe circumference, and the opening area is concentrated within 120° above the axis of the first permeable pipe; the first permeable pipe is wrapped with a double-layer filter structure, the inner layer is a needle-punched non-woven geotextile with a weight of 200 g / m², and the outer layer is a graded gravel coating layer with a particle size of 5 - 10 mm, and the coating layer thickness is ≥ 150 mm; when installing the first permeable pipe, it is fixed with precast concrete saddle-shaped supports with a support spacing of 2.0 - 2.5 meters, and a 10 cm thick medium-coarse sand leveling layer is set at the bottom; the HDPE connecting pipe uses an HDPE double-wall corrugated pipe with a nominal diameter of DN300, one end of which is connected to the first permeable pipe through a hot melt socket joint, and the other end is connected to a steel short pipe embedded in the side wall of the drainage open ditch through a flange. The length of the HDPE connecting pipe is dynamically adjusted according to the on-site height difference. A precast concrete saddle-shaped support is set every 2 meters for the HDPE connecting pipe to be fixed, and a pollution interception basket with a pore diameter of ≤ 5 mm is set at the outlet of the steel short pipe, and the height from the bottom of the steel short pipe to the bottom of the drainage open ditch is ≥ 200 mm.

[0066] In the above technical solution, the permeable pipe adopts a spiral hole opening design, which can increase the water inlet efficiency by 40%. The hole distribution range is 120°, which can avoid bottom blockage. The numerical value of the spiral hole opening spacing can be selected between 5 - 10 cm, such as 5 cm, 7 cm, 10 cm; the numerical value of the hole diameter can be selected between 1 - 3 mm, for example, 1 mm, 2 mm, 3 mm. A professional pipe hole opening device can be used for spiral hole opening operation. The material of the permeable pipe can be selected as pipes made of polyethylene (PE) and other materials, which are easily available in the market. The permeable pipe is laid in the area that needs drainage. In the design of blind pipes in some municipal drainage projects, there are also similar hole opening designs to improve the water inlet efficiency. The setting of the hole opening spacing and diameter needs to be determined through experiments and simulation calculations according to factors such as the pipe diameter of the permeable pipe, drainage requirements, and soil characteristics. Raw materials such as polyethylene can be purchased from plastic manufacturers. Functional tests can simulate different hole opening parameters in the laboratory to measure the water inlet efficiency of the permeable pipe; on-site monitoring of the actual water inlet situation of the laid permeable pipe can be carried out. The experimental objects are permeable pipe specimens with different hole opening parameters and the permeable pipes laid on-site. The experimental method is to record the water inlet flow rate and the bottom blockage situation. By statistically analyzing the relationship between different hole opening parameters and the water inlet efficiency and blockage situation, the optimal hole opening parameters are determined. The spiral hole opening design can improve the water inlet efficiency of the permeable pipe and avoid bottom blockage.

[0067] In the above technical solution, the double-layer filter structure can intercept more than 95% of fine particles, and the water permeability requirement of the graded gravel coating layer is > 5 cm / s. The double-layer filter structure can select the combination of geotextile and filter screen. The geotextile can be selected as polyester filament geotextile, and the filter screen can be selected as stainless steel filter screen. The graded gravel can be made of crushed stones such as limestone and granite through gradation design. The double-layer filter structure is wrapped on the outer layer of the permeable pipe, and the graded gravel coating layer is further wrapped outside the double-layer filter structure. In the design of drainage bodies in water conservancy projects, filter structures are also widely used to prevent fine particles from entering the drainage system. The material specifications of the double-layer filter structure and the gradation range of the graded gravel need to be determined according to the analysis results of soil particles in the drainage area. The geotextile and filter screen are purchased from relevant material manufacturers, and the crushed stones are obtained from stone quarries. Functional tests can make specimens with different material combinations and gradations in the laboratory to measure their ability to intercept fine particles and water permeability; on-site sampling inspection of the laid structure can be carried out. The experimental objects are specimens of double-layer filter and graded gravel coating layer with different material combinations and gradations and the on-site laying area. The experimental method is to record the proportion of intercepted fine particles and water permeability data through simulated water flow and particle filtration tests. By statistically analyzing the relationship between different material combinations and gradations and the interception effect and water permeability, the optimal design scheme is determined. The double-layer filter and graded gravel coating layer can effectively intercept fine particles and ensure the water permeability of the permeable pipe.

[0068] In the above technical solution, the saddle support is used to fix the permeable pipe, so that the pipeline settlement difference < 2 mm / m. The sand leveling layer can eliminate 80% of the foundation unevenness. The saddle support can choose products made of cast iron or plastic, and the sand leveling layer can choose medium coarse sand. The saddle support is installed below the permeable pipe and arranged at a certain interval; the sand leveling layer is laid between the foundation and the permeable pipe. In the pipeline laying of bridges and the installation of water supply and drainage pipelines in buildings, similar support fixing and leveling measures are also adopted. The spacing of the saddle support and the thickness of the sand leveling layer need to be determined according to factors such as the pipe diameter, weight of the pipeline, and bearing capacity of the foundation. The cast iron and plastic supports are purchased from relevant support manufacturers, and the medium coarse sand is obtained from the sand yard. Functional tests can simulate different foundation conditions and support spacings in the laboratory to measure the settlement difference of the pipeline; on-site settlement monitoring and foundation unevenness detection are carried out on the laid pipeline. The experimental objects are the pipeline laying models with different support spacings and sand leveling layer thicknesses and the on-site laid pipelines, and the experimental method is to record the settlement data and the improvement of the foundation unevenness. By statistically analyzing the relationship between different support spacings, sand leveling layer thicknesses and settlement differences, and the elimination effect of foundation unevenness, the optimal design parameters are determined. The saddle support fixing and the sand leveling layer can ensure the stability of the pipeline, reduce the settlement difference and eliminate the influence of foundation unevenness.

[0069] In the above technical solution, the sewage interception basket can capture debris > 5 mm and reduce the maintenance and cleaning frequency by 90%. The length of the connecting pipe can be dynamically adjusted to adapt to a differential settlement of 300 mm. The ring stiffness of the double-wall corrugated pipe ≥ 8 kN / m², and it has excellent compressive performance. The sewage interception basket can choose products made of stainless steel, and the connecting pipe can choose an expansion pipe made of rubber or plastic. The double-wall corrugated pipe can choose a pipe made of polyvinyl chloride (PVC). The sewage interception basket is installed at the water inlet of the permeable pipe, the connecting pipe connects different permeable pipe sections, and the double-wall corrugated pipe is used as the main drainage pipe. In the design of inspection wells in urban drainage pipe networks, similar sewage interception devices are also set. The aperture of the sewage interception basket and the expansion range of the connecting pipe need to be determined according to the debris situation in the drainage area and the possible settlement difference. Raw materials such as stainless steel, rubber, plastic, and polyvinyl chloride are purchased from corresponding manufacturers. Functional tests can simulate different debris particle sizes and settlement conditions in the laboratory to test the capture ability of the sewage interception basket and the adaptation ability of the connecting pipe; on-site actual operation monitoring of the drainage system is carried out. The experimental objects are sewage interception baskets with different apertures, connecting pipes with different expansion ranges, double-wall corrugated pipe specimens, and on-site drainage systems. The experimental method is to record the debris capture situation, the expansion performance of the connecting pipe, and the compressive performance of the double-wall corrugated pipe. By statistically analyzing the relationship between different parameters and the debris capture rate, settlement adaptation ability, and compressive performance, the optimal design parameters are determined. The design of the sewage interception basket and the connecting pipe can effectively capture debris, adapt to settlement differences, and ensure the normal operation of the drainage system.

[0070] This design enables the drainage system flux to remain > 0.8 m³ / min. Through the synergistic effect of each part, the water inlet efficiency, anti-clogging ability, stability, and compressive performance of the drainage system are improved, the frequency of maintenance and cleaning is reduced, and the drainage requirements of the project can be met.

[0071] In another embodiment of the present invention, it further includes setting a surcharge berm at the toe of the slopes on both sides of the subgrade. The top width of the berm is 2 - 2.5 meters, the height is 1.0 meter, and the filler of the berm also uses lime-improved soil. After the filling is completed, preloading is implemented, and sand drains are used for drainage consolidation. The spacing of the sand drains is 1.1 - 1.3 meters, and the depth penetrates the soft soil layer and enters the bearing layer by no less than 0.5 meter. The preloading load is 1.2 - 1.3 times the design load.

[0072] In the above technical solution, the surcharge berm is set at the toe of the slopes on both sides of the subgrade, and the top width value can be selected between 2 - 2.5 meters, such as 2 meters, 2.2 meters, 2.5 meters; the height is 1.0 meter. Equipment such as loaders and bulldozers can be used for the earthwork filling operation of the berm. The filler of the berm uses lime-improved soil. The lime can be selected as ordinary building lime, and the soil material can be local clay or silty soil that meets the requirements. The surcharge berm is located at the toe of the slopes on both sides of the subgrade and plays a role in increasing the lateral restraint force. In some dam projects, similar surcharge structures are also set to enhance stability. The setting of the top width and height needs to be determined through mechanical calculations and engineering experience according to factors such as the height, slope, and geological conditions of the subgrade. The lime can be purchased from lime manufacturers, and the soil material is taken from the project site or nearby soil sources. Functional tests can be carried out by making surcharge berm models with different top widths and heights in the laboratory for mechanical property tests; lateral pressure monitoring is carried out on the completed surcharge berm on site. The experimental objects are surcharge berm models with different top widths and heights and the on-site berm, and the experimental method is to simulate the stress condition of the subgrade and record the lateral pressure data and the deformation condition of the subgrade. By statistically analyzing the relationship between different sizes and the lateral restraint force and the stability of the subgrade, the optimal size is determined. The design of the surcharge berm can generate a lateral restraint force > 30 kPa, increasing the subgrade stability coefficient from 1.1 to 1.5 and enhancing the subgrade stability.

[0073] In the above technical scheme, bagged sand wells are used for drainage and consolidation, and the spacing between sand wells can be selected between 1.1 and 1.3 meters, such as 1.1 meters, 1.2 meters, and 1.3 meters; the depth needs to penetrate the soft soil layer and enter the bearing layer by no less than 0.5 meters. Bagged sand wells can be constructed using equipment such as pile drivers. Sand bags can be made of polypropylene woven bags with a water permeability of ≥5×10⁻²cm / s, filled with medium-coarse sand with a particle size of 0.5-2mm and a mud content of ≤1%. Bagged sand wells are arranged in a plum blossom shape within the range of the back pressure berm. In soft soil foundation treatment projects, bagged sand well drainage and consolidation is a common treatment method. The spacing and depth of sand wells should be determined through geological surveys and calculations based on the thickness and properties of the soft soil layer and the requirements of the project for drainage effects. Polypropylene woven bags and medium-coarse sand can be purchased from relevant material suppliers on the market. Functional testing can be done in the laboratory by making bagged sand well models with different spacing and depths to conduct drainage consolidation tests; on site, pumping tests and soft soil moisture content monitoring can be conducted on the constructed bagged sand wells. The experimental objects are bagged sand well models with different spacing and depths and on-site sand wells. The experimental method is to record drainage flow, soft soil moisture content changes and compression modulus data. The relationship between different parameters and drainage effects and changes in soft soil properties is statistically analyzed to determine the optimal parameters. Drainage consolidation of bagged sand wells reduces the soft soil moisture content from 45% to 28%, and increases the compression modulus by 3 times, effectively improving the performance of soft soil foundations.

[0074] In the above technical scheme, the implementation of 1.2-1.3 times overload preloading, such as 1.2 times, 1.25 times, and 1.3 times, can eliminate 80% of post-construction settlement. Preloading is implemented in three stages. The first stage is loaded with 60% of the design load for 7 days, the second stage is loaded to 100% for 14 days, and the third stage is loaded to 120-130% for 28 days. The loading rate is ≤5kPa / d. Equipment such as jacks can be used for loading operations, and pressure sensors and other equipment are required to monitor the loading pressure. Loading materials can be sandbags, stones and other heavy objects. Loading is carried out after the back pressure berm is completed, acting on the berm and roadbed. In the foundation treatment of some large-scale construction projects, the overload preloading method is also used. Parameters such as preloading load multiples, loading classification and stabilization time need to be determined according to the nature of the foundation soil, design requirements and field tests. Loading materials can be purchased from the local building materials market. Functional testing can be carried out by selecting different test areas on site, conducting preloading tests according to different loading schemes, and monitoring settlement data. The test objects are test areas with different loading schemes, and the experimental method is to record the settlement amount, settlement rate, and pore water pressure changes during each level of loading. The relationship between different loading schemes and settlement elimination effects is statistically analyzed to determine the best loading scheme. 1.2 times overload preloading eliminates 80% of post-construction settlement, improves the stability of the roadbed, and reduces later settlement.

[0075] In the above technical solution, the berm is filled with lime-improved soil to form a continuous waterproof barrier with a permeability coefficient of <1×10⁻ 6 cm / s. During the construction process, the construction process of lime-improved soil is similar to that of lime-improved soil for roadbed, and parameters such as lime content and water content need to be controlled. Lime-improved soil is filled in the counter-pressure berm area to form a waterproof barrier. Similar lime-soil anti-seepage structures are also used in the anti-seepage treatment of dams in some water conservancy projects. Waterproof performance parameters such as permeability coefficient can be determined through indoor permeability tests and on-site tests. The sources of lime and soil are the same as those of counter-pressure berm fillers. Functional testing can be carried out by making lime-improved soil specimens in the laboratory and conducting permeability tests; sampling and testing of lime soil on the berm is carried out on site. The experimental objects are lime-improved soil specimens with different proportions and lime soil on the on-site berm. The experimental method is to conduct permeability tests in accordance with relevant standards and record permeability coefficient data. The relationship between different proportions and permeability coefficients is statistically analyzed to determine the optimal lime proportion and other proportion parameters. The lime soil filling of the road protection forms a continuous waterproof barrier, which effectively prevents water from seeping into the roadbed and improves the slope safety factor from 0.9 to 1.3. It is particularly suitable for riverside sections with slopes greater than 1:1.5.

[0076] In another embodiment of the present invention, the bagged sand wells of the back pressure berm are arranged in a plum blossom shape, and the sand bags are made of a material with a water permeability of ≥5×10 -2 cm / s polypropylene woven bags filled with medium-coarse sand with a particle size of 0.5-2mm and a mud content of ≤1%; during the construction of the sand well, a 300mm diameter hole is pre-drilled, and after the bottom of the hole enters the bearing layer, a 20cm thick transition layer of crushed stone with a particle size of 10-20mm is backfilled, and then the sand bags are implanted to the designed elevation; the berm is filled with a horizontal layering method, with a virtual thickness of 0.35-0.40 meters for each layer, and an 18-ton convex roller is used for 4-6 times, with the wheel track overlapping ≥1 / 3 and a compaction degree ≥92%; the preloading is implemented in three stages, the first stage is loaded with 60% of the design load and stabilized for 7 days, the second stage is loaded to 100% and stabilized for 14 days, and the third stage is loaded to 120-130% and stabilized for 28 days, the loading rate is ≤5kPa / d, and pore water pressure gauges and settlement observation piles are buried simultaneously to control the differential settlement rate to ≤2mm / d.

[0077] In the above technical solution, the three - stage loading control is used to improve the degree of foundation consolidation. The first - stage loading can be selected between 30% - 40% of the design load, such as 30%, 35%, 40%; the second - stage loading is up to 60% - 70% of the design load, for example, 60%, 65%, 70%; the third - stage loading is up to 100% of the design load. Loading equipment such as jacks can be used for operation, and these equipment are relatively common in the construction market. During the loading process, a pore - pressure gauge is used to monitor the dissipation of excess pore pressure, and ensure that the next - stage loading is carried out after the excess pore pressure dissipation > 90%. The pore - pressure gauges should be arranged at different depths and positions of the foundation to accurately monitor the change of excess pore pressure. In the treatment of soft soil foundations of some large - scale buildings, there is a similar process of staged loading and pore - pressure monitoring. The loading ratio and loading time interval can be determined through calculation and on - site tests according to the properties of the foundation soil and design requirements. Equipment such as jacks can be purchased from relevant equipment suppliers, and pore - pressure gauges can be bought from professional instrument manufacturers. Functional tests can set up test areas with different loading schemes on - site, use pore - pressure gauges to monitor the change of excess pore pressure in real - time, and record the degree of foundation consolidation after each stage of loading. The experimental object is the test area with different loading schemes, and the experimental method is to measure the dissipation ratio of excess pore pressure and the degree of foundation consolidation. By statistically analyzing the relationship between different loading schemes and the degree of foundation consolidation and the dissipation of excess pore pressure, the optimal loading scheme is determined. Through the three - stage loading control, the degree of foundation consolidation reaches 95%, and the efficiency is increased by 50% compared with the conventional single - stage loading, effectively improving the efficiency of foundation treatment.

[0078] In the above technical solution, the purpose of differential settlement rate control is to ensure the pavement evenness. By controlling measures such as loading rate and loading range, the pavement evenness deviation < 3mm / 3m. Measuring equipment such as a level can be used to monitor the pavement evenness and differential settlement. The level should be arranged at different positions on the pavement and measured regularly. In road construction, controlling the pavement evenness is a common requirement. The control parameters of the differential settlement rate can be determined according to the pavement design standard and foundation conditions. The level can be purchased from measuring instrument suppliers. Functional tests can measure the pavement evenness during the construction process for different construction stages and record the differential settlement data. The experimental object is the pavement under construction, and the experimental method is to use a level to measure the elevation difference at different positions. By statistically analyzing the pavement evenness and differential settlement rate under different construction stages and different control measures, the optimal control method is determined. The differential settlement rate control can ensure the pavement evenness and meet the engineering use requirements.

[0079] In the above technical solution, the sand well gravel transition layer is laid between the sand bags and the superstructure, and medium-coarse sand and gravel can be selected as materials. The particle size of the medium-coarse sand is between 0.5 - 2 mm, and the particle size of the gravel is between 20 - 40 mm. Polypropylene woven bags are used to wrap the sand wells, and their tensile strength ≥ 25 kN / m. The sand well gravel transition layer can avoid a sand bag breakage rate of 60%. Equipment such as loaders can be used for the laying operation of the sand well gravel transition layer. The sand well gravel transition layer is laid on top of the sand bags, and the polypropylene woven bags wrap the sand inside the sand wells. In some soft soil foundation treatment projects, a similar transition layer and sand bag structure are also adopted. The material gradation and thickness of the sand well gravel transition layer can be determined according to the performance of the sand bags and the engineering requirements. The medium-coarse sand and gravel can be purchased from local sand and gravel quarries, and the polypropylene woven bags are purchased from plastic product manufacturers. Functional tests can be carried out in the laboratory by making specimens of sand well gravel transition layers with different gradations and thicknesses, simulating the action of the upper load, and observing the breakage of the sand bags; tensile strength tests are carried out on the polypropylene woven bags. The experimental objects are specimens of sand well gravel transition layers with different gradations and thicknesses and polypropylene woven bags, and the experimental method is to record the sand bag breakage rate and the tensile strength of the woven bags. By statistically analyzing the relationship between different material gradations, thicknesses and the sand bag breakage rate, the tensile strength of the woven bags, the optimal design scheme is determined. The sand well gravel transition layer and the polypropylene woven bags can protect the sand bags and improve the stability of the sand wells.

[0080] In the above technical solution, the bump roller compaction is used to improve the interlayer bite force. The bump height of the bump roller can be selected between 20 - 30 mm, such as 20 mm, 25 mm, 30 mm. Through the bump roller compaction, the surface roughness > 2 mm, and the interlayer bite force is increased by 30%. Bump roller equipment can be used for the compaction operation, and the bump roller should perform reciprocating compaction on the surface of the filling layer. In some road base construction, a similar compaction method is also adopted to improve the interlayer bonding force. The bump height and the number of compaction passes can be determined according to the properties of the filling materials and the design requirements. The bump roller equipment can be purchased from construction equipment suppliers. Functional tests can be carried out by selecting different test areas on site, using bump rollers with different bump heights for compaction, and measuring the surface roughness and the interlayer bite force. The experimental objects are the filling layers in different test areas, and the experimental method is to measure the surface roughness with a roughness meter and measure the interlayer bite force through a shear test. By statistically analyzing the relationship between different bump heights and the number of compaction passes and the surface roughness, the interlayer bite force, the optimal compaction parameters are determined. The bump roller compaction can improve the interlayer bite force and enhance the integrity of the structure.

[0081] Through the coordinated action of each part, this process shortens the preloading period from 180 days to 90 days, and the post-construction settlement rate < 0.1 mm / d, meeting the subgrade control standards for high-speed railways, effectively improving the foundation treatment efficiency and subgrade quality.

[0082] The number of devices and the processing scale described herein are used to simplify the description of the present invention. Applications, modifications, and variations of the method for treating the roadbed in the swamp area of the present invention will be apparent to those skilled in the art.

[0083] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to specific details.

Claims

1. A method for treating roadbed in swampy areas, characterized in that: include: Dig two parallel open drainage ditches at longitudinal intervals in the treated area on the top surface of the roadbed; A foundation trench is excavated between the two open drainage ditches, with the bottom of the foundation trench excavated to 0.5 meters below the groundwater level, and the width of the foundation trench exceeds the designed width of the roadbed by 1 meter on both sides; A crushed stone cushion layer with a thickness of 0.3-0.4 meters is laid at the bottom of the foundation trench, and the surface of the crushed stone cushion layer is covered with a biaxially stretched plastic geogrid; Lime-improved soil is filled in layers on the geogrid, with each layer having a thickness of 0.25-0.30 meters. Vibratory roller is used for compaction, and the density is controlled to be ≥93%; A composite anti-seepage layer is laid on the top surface of the lime-improved soil fill body. The composite anti-seepage layer consists of a 0.15-0.20-meter-thick cement stabilization layer, a 0.6-0.8-mm-thick HDPE geomembrane, and a 0.2-0.3-meter-thick medium-coarse sand protective layer from bottom to top; The first permeable pipe with a diameter of 200-250 mm is buried along the longitudinal center line of the roadbed. The first permeable pipe is buried 1.2 meters deep in the soil, the opening rate of the pipe wall is 15%, the longitudinal slope of the first permeable pipe is consistent with the designed longitudinal slope of the roadbed, and the first permeable pipe is connected to the open drainage ditch through multiple HDPE connecting pipes; The fineness of quicklime for lime-improved soil is controlled to be ≤5mm and the digestion rate is ≥90%. The secondary lime-adding process is adopted during mixing, and the total addition amount is 6%-8%. 5% quicklime is added for the first time to crush and turn the in-situ soil. After turning and drying, the particle size of the soil blocks is ≤50mm, and the moisture content is controlled within the range of the optimal moisture content ±2%. After aging for 48 hours, the remaining quicklime is added for the second time and mixed until the coefficient of variation of the ash dosage is ≤5%.

2. The method for treating roadbed in swampy areas according to claim 1, characterized in that: The cross-section of the open drainage ditch is inverted trapezoidal, with a top width of 1.2-1.5 meters, a bottom width of 0.6-0.8 meters, and a depth of 1.8-2.0 meters; a permeable geotextile and a crushed stone filter layer with a particle size of 20-40mm are laid at the bottom of the open drainage ditch in sequence, and the thickness of the crushed stone filter layer is not less than 0.3 meters; a collection well is set at a longitudinal interval of 50-60 meters in the open drainage ditch, and the depth of the collection well is 0.5 meters lower than the bottom of the open drainage ditch. The well wall adopts a permeable concrete prefabricated pipe with an inner diameter of 600mm, and is connected to the external drainage system through a HDPE drainage pipe with an inner diameter of 200mm.

3. The method for treating roadbed in swampy areas according to claim 1, characterized in that: When the foundation trench is excavated, the slope is controlled at 1:1.2-1.3, and a composite anti-seepage layer consisting of a waterproof geomembrane with a thickness of ≥1.0mm and a needle-punched non-woven geotextile of 400g / m² is laid on the slope. A horizontal drainage blind ditch system is set at the bottom of the foundation trench. The blind ditch spacing is 3-4 meters. It consists of a second permeable pipe with a diameter of 150mm, which is wrapped with graded crushed stone with a particle size of 10-20mm, and the graded crushed stone is wrapped with a permeable geotextile of 200g / m². A settlement monitoring point is set at the bottom of the foundation trench. The settlement of the foundation trench is monitored by a combination of a static level and an inclinometer buried in the soil. The longitudinal spacing between adjacent settlement monitoring points is ≤30 meters. Among them, the settlement monitoring point adopts a split intelligent monitoring device, which includes an independently installed sensor module and a power supply and communication module. The sensor module consists of a static level, a dual-axis MEMS inclinometer and a temperature compensation module, and the whole is encapsulated in a -40℃ low temperature resistant The power supply and communication module is connected to the sensor module through an impermeable armored cable. The power supply and communication module has a built-in supercapacitor group and a low-power NB-IoT transmission unit. The impermeable armored cable is laid in an S-shaped redundant manner on the bottom of the foundation trench, with a 20% length margin reserved. A precast concrete base with a spiral anchor is provided at the bottom of the sensor module. The precast concrete base is inserted into the soil at the bottom of the foundation trench through the anchor. The top surface of the precast concrete base is 20 cm higher than the bottom of the foundation trench, and the outer surface is covered with a high-density polyethylene impermeable membrane. The monitoring device uses an adaptive Kalman filter algorithm to process multi-source sensor data. When the deviation of the settlement estimated values ​​of the static level and the inclinometer exceeds 1.5 mm, the data fusion compensation program is automatically started to correct the settlement value. When the settlement rate of the settlement monitoring point exceeds 0.5 mm / d or the cumulative settlement exceeds 80% of the design allowable value, the early warning mechanism is triggered.

4. The method for treating roadbed in swampy areas according to claim 3, characterized in that: When the settlement estimation deviation between the static level and the inclinometer exceeds 1.5 mm, the multi-source data fusion compensation procedure is started, including: firstly applying Butterworth low-pass filtering to the static level data to eliminate high-frequency vibration noise, and then performing sliding window mean filtering on the inclinometer data, and then calculating the dual sensor confidence weight factors α and β by singular value decomposition method, α+β=1; performing weighted fusion calculation based on the confidence weight factors, and outputting the compensated settlement value S=α×S 水准仪 +β×S 倾斜计 , where S 水准仪 is the estimated settlement value of the static level, S 倾斜计 is the estimated settlement value of the inclinometer.

5. The method for treating roadbed in swampy areas according to claim 1, characterized in that: The crushed stone used in the gravel cushion layer is 5-40mm graded continuous gravel, among which the particle content of particles ≤5mm is ≤15%, and the mud content is ≤3%. The crushed stone cushion layer is laid in two layers, the lower layer is paved with 20-40mm crushed stone with a thickness of 15-20cm, and the upper layer is paved with 5-20mm crushed stone with a thickness of 10-20cm; the tensile strength of the biaxially stretched plastic geogrid is ≥50kN / m, the node peeling force is ≥300N, the width is 4-6 meters, and the adjacent widths are overlapped with 30cm wide and fixed with U-shaped nails. The U-shaped nails are arranged in a plum blossom shape with a longitudinal spacing of 1 meter; after the geogrid is laid, coarse sand with a particle size of 2-5mm is evenly spread to form a 3-5mm thick buffer layer, and then lime-improved soil is filled.

6. The method for treating roadbed in swampy areas according to claim 1, characterized in that: When lime-improved soil is layered on the geogrid, the thickness of the lower layer is 0.28-0.30 meters, and a 25-30 ton vibratory roller is used to roll it 6-8 times at a speed of 2.5-3.0 km / h, with a vibration frequency of 28-32 Hz. The thickness of the upper layer is 0.25-0.27 meters, and an 18-22 ton vibratory roller is used to roll it 4-6 times at a speed of 3.0-3.5 km / h, with a vibration frequency of 35-40 Hz. When the density is tested by the sand filling method after each layer is compacted, the sampling depth is 2 / 3 of the compacted layer thickness, the longitudinal spacing of the measuring points is ≤20 meters and there are no less than 6 measuring points per 1,000 square meters. After filling, cover with permeable geotextile and sprinkle water for maintenance to keep the moisture content of the improved soil at 12%-15%, and the maintenance time is ≥48 hours.

7. The method for treating roadbed in swampy areas according to claim 1, characterized in that: The cement stabilization layer of the composite anti-seepage layer adopts 4.5%-5.5% cement content, the aggregate is continuous graded crushed stone with a particle size of ≤20mm and a plasticity index of ≤6, and the compaction degree is ≥95%; the double-layer paving process is adopted during construction, the lower layer is paved with a thickness of 8-10cm and a cement content of 4.5%, the upper layer is paved with a thickness of 7-10cm and a cement content of 5.5%, and the cement paste binder with a water-cement ratio of 0.4 is sprayed between the layers. After paving, the plastic film is covered and watered for curing for 7 days; H DPE geomembrane adopts double weld hot-melt welding, the welding temperature is controlled at 220-250℃, the speed is 1.5-2.0m / min, the weld strength is ≥80% of the parent material, and an additional layer of 300mm width is added above and below the joints; the medium-coarse sand protective layer has a sand particle size of 0.25-5mm and a mud content of ≤1%. The layered rolling process is adopted, and the thickness of each layer is 15cm. It is compacted with a flat plate to a relative density of ≥0.7, and a 2%-3% lateral drainage slope is formed on the surface.

8. The method for treating roadbed in swampy areas according to claim 1, characterized in that: The openings on the wall of the first water-permeable pipe are long strips with a length of 20-30mm and a width of 1.5-2.0mm. They are arranged in a spiral staggered pattern along the circumference of the pipe, and the opening area is concentrated within a range of 120° above the axis of the first water-permeable pipe. The first water-permeable pipe is wrapped with a double-layer anti-filtration structure, with an inner layer of 200g / m² needle-punched non-woven geotextile and an outer layer of 5-10mm graded crushed stone coating layer with a coating thickness of ≥150mm. The first water-permeable pipe is fixed with prefabricated concrete saddle supports during installation, with a support spacing of 2.0-2.5 meters and a 1 0cm thick medium-coarse sand leveling layer; the HDPE connecting pipe adopts HDPE double-wall corrugated pipe with a nominal diameter of DN300, one end of which is connected to the first permeable pipe through a hot-melt socket joint, and the other end is connected to the pre-buried steel short pipe on the side wall of the open drainage ditch through a flange. The length of the HDPE connecting pipe is dynamically adjusted according to the height difference on site. A precast concrete saddle support is set every 2 meters for fixing the HDPE connecting pipe. A sewage intercepting basket with a pore size of ≤5mm is set at the outlet of the steel short pipe, and the bottom of the steel short pipe is ≥200mm above the bottom of the drainage ditch.

9. The method for treating roadbed in swampy areas according to claim 1, characterized in that: It also includes setting up counter-pressure guardrails at the foot of the slope on both sides of the roadbed. The top width of the guardrail is 2-2.5 meters and the height is 1.0 meter. The guardrail filling material also uses lime-improved soil. After filling is completed, pre-loading is implemented and bagged sand wells are used for drainage and consolidation. The spacing between the sand wells is 1.1-1.3 meters, and the depth of penetrating the soft soil layer into the bearing layer is not less than 0.5 meters. The pre-loading load is 1.2-1.3 times the design load.

10. The method for treating roadbed in swampy areas according to claim 9, characterized in that: The bagged sand wells of the back pressure berm are arranged in plum blossom shape, and the sand bags are made of water permeability ≥5×10 -2 cm / s polypropylene woven bags filled with medium-coarse sand with a particle size of 0.5-2mm and a mud content of ≤1%; during the construction of the sand well, a 300mm diameter hole is pre-drilled, and after the bottom of the hole enters the bearing layer, a 20cm thick transition layer of crushed stone with a particle size of 10-20mm is backfilled, and then the sand bags are implanted to the designed elevation; the berm is filled with a horizontal layering method, with a virtual thickness of 0.35-0.40 meters for each layer, and an 18-ton convex roller is used for 4-6 times, with the wheel track overlapping ≥1 / 3 and a compaction degree ≥92%; the preloading is implemented in three stages, the first stage is loaded with 60% of the design load and stabilized for 7 days, the second stage is loaded to 100% and stabilized for 14 days, and the third stage is loaded to 120-130% and stabilized for 28 days, the loading rate is ≤5kPa / d, and pore water pressure gauges and settlement observation piles are buried simultaneously to control the differential settlement rate to ≤2mm / d.