Roadbed construction method across V-shaped valley area

Abstract

The present invention relates to a roadbed construction method that crosses a V-shaped valley area, and belongs to the field of foundation engineering and foundation treatment technology. The method solves the problems of low foundation drainage efficiency, instability of fill slopes, and differential settlement control in V-shaped valley roadbed construction. The technical solution includes: excavating trenches along the bottom of the valley and laying gravel drainage blind ditches wrapped with permeable geotextiles to form a foundation drainage system; using a vibratory roller with a piezoelectric sensor embedded in a steel wheel during layered filling; laying a one-way geogrid along the slope after every two layers of filling and vertically anchoring it into the compacted layer through U-shaped anchors; pre-buried transverse drainage pipes when filling to the threshold of the foundation bearing capacity mutation point; and laying a settlement monitoring array after filling is completed. This method significantly improves the bearing stability of fill roadbeds under complex terrain through the system integration of foundation drainage structure optimization, intelligent compaction of fill bodies, and dynamic processing of differential settlements. It is suitable for foundation construction and disaster prevention and control in V-shaped canyon sections of mountain roads.

Description

Technical Field

[0001] The present invention relates to the technical field of foundation engineering and ground treatment, and more particularly to a roadbed construction method for crossing a V-shaped valley area. Background Art

[0002] When implementing roadbed filling projects in V-shaped valley areas, the special terrain conditions pose multiple challenges to construction technology. In existing technologies, drainage system designs usually adopt a single drainage blind ditch structure. Its gravel filling layer is prone to local packing density differences due to the irregular terrain of the valley bottom, and the contact interface between the permeable geotextile and the filling body is prone to misalignment, resulting in discontinuous drainage paths. This phenomenon is due to the significant changes in the lateral slope of the V-shaped valley bottom. Conventional straight-line blind ditches are difficult to adapt to the longitudinal undulations, and there is a lack of coordinated control of the gravel particle size and the extension length of the permeable geotextile during construction, resulting in a significant decrease in the permeability coefficient of the blind ditch during the filling process. In addition, the top cover layer of the blind ditch is prone to structural deformation when heavy compaction equipment is operating, causing blockage of the drainage channel. After the filling is completed, the effective water flow area of ​​the blind ditch is significantly reduced.

[0003] For slope stability control, the traditional layered fill process uses excessively large geogrid spacing, causing the spacing between the grid's load-bearing layers to exceed reasonable limits. The lateral earth pressure on V-shaped valley fill slopes increases nonlinearly with fill height, but the existing anchor spacing is unable to effectively disperse stress concentration areas. This is particularly true in areas with sudden changes in foundation bearing capacity, where the anchors experience a significant loss in pullout resistance. Furthermore, when the vertical insertion angle of the U-shaped rebar anchor deviates significantly, its ability to synergize with the geogrid node is reduced, resulting in a decrease in the utilization rate of the grid's tensile strength.

[0004] In terms of differential settlement control, traditional methods rely on surface settlement observations after roadbed formation. However, V-shaped valley fills often experience hidden uneven settlement due to sudden changes in the foundation's bearing capacity. Existing technologies often rely on static analysis of geological exploration data to identify sudden changes in foundation bearing capacity, failing to consider the dynamic response during the filling and loading process. When the rate of change of the foundation's compression modulus accelerates, traditional methods struggle to capture critical states in a timely manner, leading to increased deviations in the thickness design of subsequent fill layers. Furthermore, the control of the paving thickness of the graded gravel layer is affected by changes in the longitudinal slope. These changes in slope cause the paving thickness deviation to gradually increase, directly impacting surface drainage performance.

[0005] When it comes to compaction quality control, conventional vibratory rollers rely on operator experience to adjust compaction parameters, resulting in a slow response to filler non-uniformity. Variations in filler moisture content significantly increase the compaction coefficient, leading to weak zones forming at the junction of adjacent rolling sections, resulting in lower compaction than normal. Existing compaction testing techniques rely on spot checks, which are unable to effectively identify localized compaction defects, resulting in a high percentage of substandard areas being missed.

[0006] For internal drainage of landfill, traditional lateral drainage pipes are often buried at fixed elevations, failing to account for the dynamic impact of ground settlement during the filling process. When the landfill continues to compress and deform, pre-buried drainage pipes are prone to longitudinal displacement, leading to failure of their connection to the blind ditch. Furthermore, the overlap between the drainage pipe's filter geotextile and the blind ditch's permeable geotextile lacks continuity assurance measures. Significant differences in interfacial permeability can create a drainage barrier, reducing drainage efficiency.

[0007] When it comes to reinforcing areas of differential settlement, existing technologies often use uniform grouting parameters, failing to consider the spatial variation of soil permeability. When there are significant differences in soil permeability across the reinforcement area, conventional grouting pressure settings can lead to insufficient slurry diffusion in low-permeability areas and severe slurry loss in high-permeability areas. Furthermore, the accuracy of ground-penetrating radar (GPR) data interpretation is affected by reflections from filler layer interfaces. Large interface misalignments increase porosity measurement errors, directly impacting the accuracy of reinforcement planning.

[0008] The combined effects of these technical issues often lead to high maintenance costs and shortened service life for V-shaped valley roadbed projects. This is particularly true in rainy mountainous areas, where the risk of slope slippage caused by water accumulation within the fill volume increases significantly. Existing technical improvements often focus on optimizing single subsystems, lacking research on the synergistic mechanisms of drainage structures, filling processes, and settlement control. This has become a bottleneck in improving the quality of roadbed projects in complex terrain. Summary of the Invention

[0009] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0010] In order to achieve these objects and other advantages according to the present invention, a roadbed construction method for crossing a V-shaped valley area is provided, comprising the following steps:

[0011] Step 1: dig a trench longitudinally along the roadbed at the bottom of the V-shaped valley and lay a permeable geotextile, then fill it with gravel to form a drainage blind ditch. The top of the drainage blind ditch is covered with permeable geotextile and the edges on both sides extend to the roadbed fill boundary;

[0012] The roadbed fill material is laid layer by layer above and on both sides of the blind drainage ditch, covering the entire roadbed cross section. After each layer is filled, it is rolled by a vibratory roller according to a preset compaction path. The direction of travel of the vibratory roller is parallel to the longitudinal axis of the roadbed, and the overlapping width of adjacent rolling wheel tracks is 1 / 3 to 1 / 2 of the wheel width.

[0013] Step 2: After each two layers of roadbed fill are completed, a unidirectional geogrid is deployed longitudinally on the slope surface of the roadbed. The laying direction of the unidirectional geogrid is consistent with the longitudinal direction of the roadbed and is vertically inserted into the compacted fill layer through U-shaped steel anchors. The horizontal spacing of the U-shaped steel anchors is 1.5-2m and aligned with the overlap area of ​​the geogrid.

[0014] Step 3: When the roadbed filling height reaches a preset threshold, multiple drainage pipes are pre-buried horizontally below the top surface of the roadbed. The inlet ends of the drainage pipes are connected to the drainage blind ditch through inclined connecting pipes, and the outlet ends extend to the outside of the roadbed slope. The water-filtration geotextile wrapped around the drainage pipes and the permeable geotextile of the drainage blind ditch form a continuous drainage interface;

[0015] Step 4: After the roadbed is filled to the designed elevation, a graded gravel layer is evenly spread on the roadbed surface and leveled. The paving thickness of the graded gravel layer is dynamically adjusted by elevation control piles.

[0016] After paving is completed and static curing is carried out, intercepting ditches are excavated at the foot of the slopes on both sides of the roadbed. A concrete cushion is laid at the bottom of the intercepting ditch, and the longitudinal slope of the intercepting ditch is consistent with the drainage direction of the roadbed;

[0017] Step 5: After the self-fill is completed, an array of settlement monitoring points is laid out on the roadbed surface. The monitoring points are distributed in a grid along the longitudinal and transverse directions of the roadbed, and elevation data is collected at a fixed period using a total station. When the elevation difference between adjacent monitoring points exceeds the set threshold, reinforcement treatment is carried out in the corresponding area.

[0018] Preferably, piezoelectric dynamic compaction sensors are arranged at intervals of 200 to 300 mm inside the steel wheel of the vibratory roller to collect real-time waveform data of the reaction force of the filler during the rolling process;

[0019] The IoT control platform performs spectrum analysis on waveform data to extract the energy proportion of characteristic frequency segments. When the energy proportion is lower than the set threshold range of 65% to 75%, it is determined that the compaction degree is insufficient.

[0020] If the compaction data of three consecutive rolling sections are all below the lower threshold, the roller will be controlled to automatically increase the vibration frequency of the current rolling section by 2 to 4 Hz and perform 1 to 2 additional rolling passes;

[0021] If the energy ratio exceeds the upper threshold, the vibration frequency will be reduced by 1~2Hz, and the number of rolling times in the subsequent rolling section will be reduced by 1.

[0022] Preferably, in the boundary area between adjacent rolling sections, the roller wheel track overlap width is controlled to increase by 50-100 mm through differential positioning technology, and the vibration frequency in this area is simultaneously increased by 1-3 Hz;

[0023] After every 100-150m of rolling work, the IoT platform generates a compaction heat map. Areas with a compaction dispersion coefficient greater than 0.15 are marked as re-compaction areas, and fan-shaped paths are used for re-compaction.

[0024] The dense rolling of the fan-shaped path includes rolling in circles along concentric arc tracks with a radius of 1 to 3 meters, with the center of the re-compacting area as the center of the circle, and the spacing between adjacent arcs is 1 / 2 to 2 / 3 of the roller wheel width.

[0025] Preferably, the method for determining the preset threshold value of the roadbed filling height in step 3 includes the following steps:

[0026] Through geological exploration, the foundation bearing capacity data of different depths in the V-shaped valley section are obtained. When the cumulative thickness of the roadbed fill layer reaches 70% to 80% of the depth corresponding to the foundation bearing capacity mutation point, it is determined to be the preset threshold trigger point;

[0027] During the filling process, a settlement monitoring device is used to measure the compression deformation rate of the filled layer in real time. When the deformation rate is less than 0.5 mm / d for three consecutive days, the preset threshold judgment condition is triggered synchronously;

[0028] If the sudden change point of foundation bearing capacity and the stable deformation rate conditions are met at the same time, the buried elevation of the horizontal drainage pipe is located 1.2~1.8m below the top of the current filling layer;

[0029] If the two conditions are not met at the same time, the filling will continue until the thickness of the next layer reaches the incremental threshold of the depth corresponding to the mutation point of the foundation bearing capacity. The incremental threshold is 1.2 to 1.5 times the thickness of the single layer of filling.

[0030] Preferably, the specific method for dynamically adjusting the paving thickness of the graded gravel layer by means of elevation control piles is:

[0031] Elevation control piles are set at intervals of 5 to 8 meters along the longitudinal axis of the roadbed surface. The elevation of the top of the elevation control piles is consistent with the design elevation of the graded gravel layer.

[0032] As the paver moves, the vertical distance between the surface of the paved gravel layer and the top of the elevation control pile is measured in real time using a laser rangefinder;

[0033] When the measured vertical distance exceeds the designed paving thickness range of -10mm to +15mm, the paver's hydraulic control system will synchronously adjust the scraper opening and travel speed;

[0034] After the dynamic adjustment is completed, a continuous elevation control reference surface is formed on the surface of the graded gravel layer, and its longitudinal flatness error is controlled within the range of ±5mm / 10m.

[0035] Preferably, the method further comprises: setting an elevation re-measurement point behind the paver and using a dynamic compaction tester to obtain compaction data of the adjusted area;

[0036] When the compaction data is lower than 95% of the design value, control the vibratory roller to roll the corresponding area 1 to 2 times more;

[0037] During additional rolling, the exciting force of the vibratory roller is increased by 10%~15%, and the rolling path forms an intersection angle of 30°~45° with the original path.

[0038] Preferably, the specific method of the reinforcement treatment in step 5 includes:

[0039] When the elevation difference between adjacent monitoring points exceeds 10-15 mm, a circular difference area with a radius of 2-3 m is delineated with the point with the maximum elevation difference as the center;

[0040] In the difference area, the internal structure of the roadbed is scanned using ground penetrating radar. If the porosity is greater than 20% or the filler layer interface misalignment exceeds 50mm, high-pressure rotary grouting is used for reinforcement, and the grouting pressure is controlled at 0.8~1.2MPa.

[0041] If the fill density is detected to be 5% to 8% lower than the design value, the surface fill in the difference area shall be removed to the stable layer, and the fill shall be re-filled in layers and re-compacted with a vibratory roller with a 10% to 15% higher excitation force for 3 to 4 times;

[0042] After the processing is completed, the monitoring points in the difference area are densely distributed to 1 / 2 of the original spacing, and the monitoring cycle is shortened to 1 / 3 of the original cycle, until the fluctuation range of the monitoring data is less than 2mm for three consecutive times.

[0043] Preferably, it further comprises:

[0044] If there are signs of slope slip in the differential area, a bidirectional geogrid with a tensile strength of 100-150 kN / m will be laid on the slope surface and fixed to the deep stabilization layer of the slope with L-shaped anchors at a depth of 1.5-2 m.

[0045] The installation sequence of the L-shaped anchor rods is to construct them row by row from top to bottom. The installation interval of the anchor rods in the same row is 1.2 to 1.5 times the length of the anchor rods, and the minimum spacing shall not be less than 1.8m. The node between the tail of the anchor rod and the geogrid shall be locked by fasteners.

[0046] Preferably, the grouting pressure of the high-pressure rotary jet grouting method is dynamically adjusted according to the soil permeability coefficient of the different areas:

[0047] When the soil permeability coefficient k≥1×10 -4cm / s, the grouting pressure is controlled at 0.8~1.0MPa, the spacing between grouting holes is 0.8m×0.8m to 1m×1m, and the grouting speed is 15~20L / min;

[0048] When the soil permeability coefficient is 1×10 -6 cm / s≤k<1×10 -4 cm / s, the grouting pressure is controlled at 1.0~1.2MPa, the spacing between grouting holes is 0.6m×0.6m to 0.8m×0.8m, and the grouting speed is 10~15L / min;

[0049] When the soil permeability coefficient k < 1 × 10 -6 cm / s, a pre-cracking process is used before grouting. The spacing between pre-cracking holes is 0.5-0.7 times the spacing between grouting holes. The pre-cracking pressure is applied in stages. The initial pressure is 0.8-1.0 times the grouting pressure. The pressure is increased by 0.2 MPa for 2 minutes each time. The final pressure does not exceed 1.2 times the grouting pressure.

[0050] After grouting is completed, the slurry consolidation state is monitored by a pore water pressure sensor. If the pore water pressure dissipation rate is less than 30% of the initial value within 24 hours after grouting, slurry is injected into the adjacent hole position with an injection pressure of 80% to 90% of the original pressure.

[0051] The present invention has at least the following beneficial effects: the present invention effectively maintains the continuity of the drainage path and reduces the seepage attenuation through the continuous interface design of the gravel blind ditch and the permeable geotextile combined with the layered filling process, while the interval anchoring of the geogrid significantly improves the anti-slip ability of the slope; the intelligent compaction system based on piezoelectric sensing and Internet of Things feedback dynamically adjusts the vibration parameters to eliminate the weak compaction areas caused by the non-uniformity of the filler; the dual threshold judgment method of the foundation bearing capacity mutation point and the deformation rate realizes the early warning of differential settlement, and the ground penetrating radar is combined to accurately identify internal defects and improve the targeted reinforcement treatment; the dynamic positioning technology of the drainage pipe elevation adapts to the settlement changes of the fill body to ensure the smooth flow of the drainage pipe. The interface permeability matching of the barrier three-dimensional drainage system; the paving control technology of laser ranging and hydraulic linkage optimizes the thickness and flatness of the graded gravel layer, and enhances the surface drainage efficiency; the grouting parameter control strategy of permeability coefficient grading improves the uniformity of slurry diffusion, ensuring the balanced improvement of the bearing capacity of the reinforced area; the synergistic effect of bidirectional geogrids and deep anchors strengthens the shear strength of potential slip surfaces, and cooperates with high-frequency monitoring to achieve dynamic control of slope stability; the fan-shaped re-pressing path guided by differential positioning improves the density of the rolling handover area and reduces equipment energy consumption; the closed-loop mechanism of pore water pressure monitoring and supplementary grouting ensures that the reinforcement effect is long-lasting and stable, and significantly extends the service life of the roadbed.

[0052] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. DETAILED DESCRIPTION

[0053] The present invention will be further described in detail below in conjunction with specific embodiments so that those skilled in the art can implement the invention with reference to the description.

[0054] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0055] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0056] The present invention provides a roadbed construction method for crossing a V-shaped valley area, comprising the following steps:

[0057] Step 1: dig a trench longitudinally along the roadbed at the bottom of the V-shaped valley and lay a permeable geotextile, then fill it with gravel to form a drainage blind ditch. The top of the drainage blind ditch is covered with permeable geotextile and the edges on both sides extend to the roadbed fill boundary;

[0058] The roadbed fill material is laid layer by layer above and on both sides of the blind drainage ditch, covering the entire roadbed cross section. After each layer is filled, it is rolled by a vibratory roller according to a preset compaction path. The direction of travel of the vibratory roller is parallel to the longitudinal axis of the roadbed, and the overlapping width of adjacent rolling wheel tracks is 1 / 3 to 1 / 2 of the wheel width.

[0059] Step 2: After each two layers of roadbed fill are completed, a unidirectional geogrid is deployed longitudinally on the slope surface of the roadbed. The laying direction of the unidirectional geogrid is consistent with the longitudinal direction of the roadbed and is vertically inserted into the compacted fill layer through U-shaped steel anchors. The horizontal spacing of the U-shaped steel anchors is 1.5-2m and aligned with the overlap area of ​​the geogrid.

[0060] Step 3: When the roadbed filling height reaches a preset threshold, multiple drainage pipes are pre-buried horizontally below the top surface of the roadbed. The inlet ends of the drainage pipes are connected to the drainage blind ditch through inclined connecting pipes, and the outlet ends extend to the outside of the roadbed slope. The water-filtration geotextile wrapped around the drainage pipes and the permeable geotextile of the drainage blind ditch form a continuous drainage interface;

[0061] Step 4: After the roadbed is filled to the designed elevation, a graded gravel layer is evenly spread on the roadbed surface and leveled. The paving thickness of the graded gravel layer is dynamically adjusted by elevation control piles.

[0062] After paving is completed and static curing is carried out, intercepting ditches are excavated at the foot of the slopes on both sides of the roadbed. A concrete cushion is laid at the bottom of the intercepting ditch, and the longitudinal slope of the intercepting ditch is consistent with the drainage direction of the roadbed;

[0063] Step 5: After the self-fill is completed, an array of settlement monitoring points is laid out on the roadbed surface. The monitoring points are distributed in a grid along the longitudinal and transverse directions of the roadbed, and elevation data is collected at a fixed period using a total station. When the elevation difference between adjacent monitoring points exceeds the set threshold, reinforcement treatment is carried out in the corresponding area.

[0064] In this technical solution, when constructing a roadbed through a V-shaped valley, a trench is first excavated longitudinally along the roadbed at the bottom of the V-shaped valley. The trench depth can be determined based on the actual geological conditions, typically 1 to 2 meters. A permeable geotextile, such as polyester, is then laid, offering excellent water permeability and durability. Gravel is then filled to form a drainage blind ditch, with a particle size of 2 to 5 centimeters to ensure good drainage. The top of the drainage blind ditch is covered with the same polyester permeable geotextile, with the edges extending to the roadbed fill boundary. Roadbed fill is applied layer by layer above and on both sides of the drainage blind ditch, covering the entire cross-section of the roadbed. The thickness of each layer can be controlled to 20 to 30 centimeters. After each layer is applied, it is compacted using an optional vibratory roller, traveling parallel to the longitudinal axis of the roadbed. The overlap between adjacent rolling wheel tracks can be set to 1 / 3 of the wheel width. For example, for a 2-meter wheel width, the overlap is approximately 0.67 meters. The vibratory roller here can be selected with a deadweight of 15 to 20 tons, which has a better compaction effect and can meet the construction requirements. In step 2, after completing two layers of roadbed filling, the unidirectional geogrid is deployed longitudinally on the slope surface of the roadbed. The unidirectional geogrid can be made of high-strength polypropylene material, which has high tensile strength and can effectively enhance the stability of the slope. The U-shaped steel bar anchor is vertically inserted into the compacted filling layer, and the horizontal spacing of the U-shaped steel bar anchor can be selected to be 1.5 meters. The U-shaped steel bar anchor should be aligned with the overlap area of ​​the geogrid, and the U-shaped steel bar anchor can be made of steel bars with a diameter of 12 to 16 mm. During installation, the U-shaped steel bar anchor needs to be inserted vertically into the filling layer, and the insertion depth must ensure that the geogrid can be effectively anchored, generally 30 to 50 cm. Step 3, when the roadbed filling height reaches the preset threshold, the horizontal drainage pipe is pre-buried. The preset threshold can be determined by obtaining foundation bearing capacity data at different depths in the V-shaped valley section through geological exploration. The preset threshold trigger point is determined when the cumulative thickness of the roadbed fill reaches 70% of the depth corresponding to the sudden change in foundation bearing capacity. Multiple drainage pipes are pre-buried horizontally beneath the roadbed top surface. Polyvinyl chloride (PVC) can be used for its corrosion resistance. The inlet of the drainage pipe is connected to the drainage blind ditch via an inclined connecting pipe, also made of PVC. The outlet extends to the outside of the roadbed slope. The drainage geotextile wrapped around the drainage pipe can be the same polyester fiber permeable geotextile as the drainage blind ditch, forming a continuous drainage interface. Step 4: After the roadbed is filled to the design elevation, a graded gravel layer is evenly spread and leveled on the roadbed surface. The thickness of the graded gravel layer is dynamically adjusted using elevation control stakes. Elevation control stakes are installed every 5 meters along the longitudinal axis of the roadbed surface. These stakes can be made of reinforced concrete, and their top elevations are consistent with the design elevation of the graded gravel layer. As the paver moves, an optional laser rangefinder is used to measure in real time the vertical distance between the surface of the spread gravel layer and the top of the elevation control pile.If the measured vertical distance exceeds the designed paving thickness range of -10 mm to +15 mm, the paver's hydraulic control system synchronously adjusts the scraper opening and travel speed. After dynamic adjustment, a continuous elevation control datum is formed on the surface of the graded gravel layer, with a longitudinal flatness error controlled within ±5 mm / 1 meter. After paving is completed and static curing is completed, intercepting ditches are excavated at the toes of the slopes on both sides of the roadbed. A concrete cushion layer of C20 strength grade commercial concrete can be used at the bottom of the ditches. The longitudinal slope of the intercepting ditches aligns with the drainage direction of the roadbed to ensure smooth drainage. Step 5: After the self-fill is completed, an array of settlement monitoring points is deployed on the roadbed surface, distributed in a grid pattern along the longitudinal and transverse directions of the roadbed. An optional total station is used to collect elevation data at a fixed interval, which can be 7 days. If the elevation difference between adjacent monitoring points exceeds 10 mm, reinforcement treatment is carried out in the corresponding area.

[0065] The above construction steps effectively address challenges such as foundation drainage, slope stability, and differential settlement control during V-shaped valley roadbed construction, thereby improving the bearing stability of the fill roadbed. Regarding drainage, a blind drainage ditch at the valley bottom, combined with a permeable geotextile, and the continuous drainage interface formed by the drainage pipe and blind ditch, effectively drains accumulated water from the foundation and reduces roadbed damage caused by water accumulation. Regarding slope stability, one-way geogrids combined with U-shaped rebar anchors strengthen the connection between the slope soil and effectively prevent slope slip. During compaction, a specified rolling method and wheel track overlap width ensure uniform compaction and improve roadbed density. For differential settlement, an array of settlement monitoring points and timely reinforcement measures can control uneven roadbed settlement. With an improved drainage system and coordinated implementation of various construction steps, the roadbed's bearing capacity is increased, ensuring stability in the complex terrain of the V-shaped valley, reducing maintenance and extending its service life.

[0066] In another technical solution, piezoelectric dynamic compaction sensors are arranged inside the steel wheel of the vibratory roller at intervals of 200 to 300 mm to collect real-time waveform data of the reaction force of the filler during rolling;

[0067] The IoT control platform performs spectrum analysis on waveform data to extract the energy proportion of characteristic frequency segments. When the energy proportion is lower than the set threshold range of 65% to 75%, it is determined that the compaction degree is insufficient.

[0068] If the compaction data of three consecutive rolling sections are all below the lower threshold, the roller will be controlled to automatically increase the vibration frequency of the current rolling section by 2 to 4 Hz and perform 1 to 2 additional rolling passes;

[0069] If the energy ratio exceeds the upper threshold, the vibration frequency will be reduced by 1~2Hz, and the number of rolling times in the subsequent rolling section will be reduced by 1.

[0070] In this technical solution, the vibratory roller can be equipped with a sensor-mountable structure. Commercially available piezoelectric dynamic compaction sensors with the required accuracy can be installed inside the roller's steel drum. The sensors can be installed 250mm apart to ensure effective data collection without compromising sensor performance due to excessive close proximity. During the rolling process, the piezoelectric dynamic compaction sensors operate, collecting real-time waveform data on the filler's reaction force. This data is transmitted to the IoT control platform via an optional wireless transmission module. The IoT control platform can utilize an off-the-shelf system with spectrum analysis capabilities. This system analyzes the collected waveform data and extracts the energy percentage of characteristic frequency bands. The threshold range is set between 65% and 75%. In practice, 65% is used as the lower limit for insufficient compaction, and 75% is used as the upper limit. If the energy percentage data analyzed by the IoT control platform falls below 65%, the system will initiate a determination. If the compaction data for three consecutive rolling sections falls below this lower limit, a command will be issued to the vibratory roller. The vibratory roller receives commands from its internal intelligent control system to automatically increase the vibration frequency of the current rolling section by 3Hz. It also performs an additional rolling pass. This is because a low energy percentage indicates insufficient compaction, and increasing the vibration frequency and number of rolling passes can improve compaction. Conversely, when the energy percentage exceeds 75%, it indicates that the current rolling parameters may be causing excessive compaction. In this case, the system controls the vibratory roller to reduce the vibration frequency by 1Hz and reduce the number of rolling passes in the subsequent rolling section by one. This prevents excessive compaction and ensures construction efficiency and quality. For functional testing, a representative roadbed area can be selected as the experimental subject. Rolling operations are carried out in this area using the aforementioned construction methods. Compaction testing is also performed on the compacted roadbed using specialized compaction testing equipment, such as the sand injection method or a nuclear density meter. The test results are compared with the compaction determination results generated by the IoT control platform based on sensor data to verify the accuracy of the entire system. In terms of structural design, special attention was paid to the stability of the piezoelectric dynamic compaction sensor installed inside the steel drum to ensure its proper function in a vibrating environment. The data analysis process of the IoT control platform was streamlined to ensure accurate and timely data processing. This construction method and related operations enable timely identification of areas of insufficient or excessive compaction, enabling appropriate adjustments to be made, thereby improving the uniformity and stability of the roadbed compaction quality.

[0071] By placing piezoelectric dynamic compaction sensors within the vibratory roller's drum and integrating them with an IoT control platform for compaction control, the sensors collect reaction force waveform data in real time. The IoT platform analyzes the energy ratio to determine the compaction level. When the energy ratio falls below the threshold of 65% to 75%, areas of insufficient compaction can be promptly identified, preventing problems such as insufficient roadbed density and subsequent settlement. When the energy ratio exceeds the upper threshold, overcompaction can be prevented, ensuring stable and uniform compaction quality. Regarding construction efficiency, if the compaction level falls below the lower threshold for three consecutive rolling sections, the vibration frequency is automatically increased by 2 to 4 Hz and additional rolling is performed, rapidly improving compaction and avoiding the tedious process of repeated testing and manual adjustments. When the energy ratio exceeds the upper threshold, the vibration frequency is reduced and the number of rollings is reduced, eliminating unnecessary construction operations, rationally allocating construction resources, and shortening overall construction time. Furthermore, precise compaction control reduces rework costs due to compaction issues. By timely adjusting the rolling parameters, the one-time compaction compliance rate is improved, which reduces the additional material, equipment and manpower investment, avoids waste of resources, achieves improved economic benefits, and at the same time ensures the quality of the roadbed project, laying the foundation for subsequent long-term and stable use.

[0072] In another technical solution, at the intersection of adjacent rolling sections, the roller wheel track overlap width is controlled by differential positioning technology to increase by 50-100 mm, and the vibration frequency in this area is simultaneously increased by 1-3 Hz.

[0073] After every 100-150m of rolling work, the IoT platform generates a compaction heat map. Areas with a compaction dispersion coefficient greater than 0.15 are marked as re-compaction areas, and fan-shaped paths are used for re-compaction.

[0074] The dense rolling of the fan-shaped path includes rolling in circles along concentric arc tracks with a radius of 1 to 3 meters, with the center of the re-compacting area as the center of the circle, and the spacing between adjacent arcs is 1 / 2 to 2 / 3 of the roller wheel width.

[0075] In actual construction, when this technical solution is used in the boundary area between adjacent rolling sections, a roller with differential positioning function can be selected. Differential positioning technology is used to control the overlap width of the roller wheel track to increase by 75mm, and the vibration frequency of the area is simultaneously increased by 2Hz. The differential positioning system can choose the existing high-precision products on the market. By receiving satellite signals and comparing them with the base station data, it can accurately determine the position of the roller, thereby achieving precise control of the overlap width and vibration frequency of the wheel track. After completing each 120m of rolling operation, the Internet of Things platform begins to generate a compaction heat map. The Internet of Things platform can use a ready-made system with data processing and visualization functions. The system analyzes and processes the data from each sensor to generate an intuitive compaction heat map. In the generated heat map, the system will automatically mark the area with a compaction dispersion coefficient greater than 0.15 as a re-compaction area for subsequent targeted processing. For areas marked as re-compaction areas, fan-shaped paths are used for dense rolling. The specific operation of fan-shaped path intensified rolling is to roll the road one circle at a time along a concentric arc trajectory with a radius of 2m, centered at the center of the recompaction area. The spacing between adjacent arcs is 2 / 3 of the roller's wheel width. This spacing ensures effective rolling and improves construction efficiency. During the rolling process, the roller follows a pre-set program, starting from the center of the circle and gradually expanding outward along the concentric arc trajectory. This fan-shaped path intensified rolling method allows for more comprehensive and detailed compaction of the recompaction area, ensuring that the required compaction level is achieved. For functional testing, a section of roadbed with different compaction conditions can be selected as the experimental subject. Rolling operations are carried out in this area according to the above construction method, and the compaction level of the roadbed after rolling is tested using specialized compaction testing equipment, such as the sand injection method or a nuclear density meter. The test results are compared with the compaction heat map generated by the IoT platform to verify the accuracy of the heat map and the reliability of the recompaction area marking. In terms of structural design, emphasis was placed on the integrated stability of the differential positioning system and roller, ensuring accurate control of wheel track overlap width and vibration frequency during construction. The program for dense rolling of the fan-shaped path was optimized to ensure that the roller can operate efficiently according to the set trajectory and parameters. This construction method and related operations effectively solve the compaction problem at the interface between adjacent rolling sections, improve the overall quality and uniformity of roadbed compaction, and reduce roadbed defects caused by uneven compaction.

[0076] This technical solution, through differential positioning technology, compaction heat map marking, and fan-shaped recompaction, has significantly improved roadbed compaction quality control. At the intersection of adjacent rolling sections, differential positioning technology increases the wheel track overlap width and increases the vibration frequency. This effectively addresses the low compaction level at the intersection due to insufficient rolling connection in traditional construction. This significantly reduces the difference in compaction between the intersection and adjacent rolling sections, enhances the continuity and uniformity of the roadbed structure, and prevents localized settlement or cracking caused by weak zones later in the roadbed. The IoT platform generates a compaction heat map and marks recompaction areas, accurately identifying areas with large compaction dispersion, addressing the high miss rate of traditional sampling inspection. For these areas, fan-shaped recompaction is implemented. Concentric arcs centered around the center of the recompaction area ensure effective coverage of every area. The appropriate ratio of adjacent arc spacing to wheel width ensures zero blind spots in the recompaction area, further improving compaction quality in the recompaction area and reducing localized compaction defects caused by filler heterogeneity. The synergistic effect of the above-mentioned technical means not only avoids the energy waste caused by excessive rolling, but also solves the quality risks of insufficient compaction, significantly improves the overall uniformity of roadbed compaction under complex terrain, provides a stable support foundation for subsequent filling layers, effectively reduces the risk of diseases caused by uneven compaction during the service life of the roadbed, and ensures the long-term stability of the project.

[0077] In another technical solution, the method for determining the preset threshold value of the roadbed filling height in step 3 includes the following steps:

[0078] Through geological exploration, the foundation bearing capacity data of different depths in the V-shaped valley section are obtained. When the cumulative thickness of the roadbed fill layer reaches 70% to 80% of the depth corresponding to the foundation bearing capacity mutation point, it is determined to be the preset threshold trigger point;

[0079] During the filling process, a settlement monitoring device is used to measure the compression deformation rate of the filled layer in real time. When the deformation rate is less than 0.5 mm / d for three consecutive days, the preset threshold judgment condition is triggered synchronously;

[0080] If the sudden change point of foundation bearing capacity and the stable deformation rate conditions are met at the same time, the buried elevation of the horizontal drainage pipe is located 1.2~1.8m below the top of the current filling layer;

[0081] If the two conditions are not met at the same time, the filling will continue until the thickness of the next layer reaches the incremental threshold of the depth corresponding to the mutation point of the foundation bearing capacity. The incremental threshold is 1.2 to 1.5 times the thickness of the single layer of filling.

[0082] In this technical solution, before construction, geological surveys are conducted to obtain foundation bearing capacity data for V-shaped valley sections. Static penetration testers or drilling sampling equipment can be used. Survey points are set every 20-30 meters along the longitudinal direction of the roadbed to test the foundation bearing capacity at different depths. When processing the survey data, a bearing capacity-depth curve is plotted to identify the depth corresponding to the sudden change in foundation bearing capacity. For example, if the foundation bearing capacity at a certain survey point shows a significant change at a depth of 8 meters, this depth is identified as the sudden change point. When the cumulative thickness of the roadbed fill reaches 75% of the depth corresponding to the sudden change point (i.e., 6 meters), a pre-set threshold is triggered for preliminary assessment. This value is selected between 70% and 80% to balance safety and construction efficiency. During the filling process, settlement monitoring devices can use high-precision electronic levels or automated displacement sensors. These can be installed on the surface of the filled layer, with monitoring points set every 10-15 meters along the longitudinal direction of the roadbed to measure the soil compression deformation rate in real time. When the deformation rate is monitored to be less than 0.5 mm / day for three consecutive days, it indicates that the foundation consolidation is stabilizing, and the preset threshold judgment condition is triggered. If both the foundation bearing capacity mutation point triggering condition and the deformation rate stability condition are met at this time, the lateral drainage pipe is located at an elevation 1.5 m below the top of the current fill layer. This depth is within the recommended range of 1.2 to 1.8 m and effectively avoids areas of concentrated surface loads. High-density polyethylene (HDPE) corrugated pipe can be used for the lateral drainage pipe. The wall porosity and the specifications of the outer filter geotextile must meet drainage design requirements. If both conditions are not met simultaneously, for example, if only the bearing capacity mutation point triggering depth is reached but the deformation rate is still greater than 0.5 mm / day, fill is continued, and the thickness of the next fill layer is controlled to be 1.3 times the thickness of the single fill layer (for example, if the single layer thickness is 0.5 m, the next fill layer is 0.65 m). The incremental threshold is within a reasonable range of 1.2 to 1.5 times to ensure that the foundation gradually approaches a stable state. In the functional testing phase, a V-shaped valley section with representative geological conditions was selected as the experimental object, and manual inspection and automatic monitoring data comparison were carried out simultaneously. The compaction degree of the filled layer was detected by the sand injection method, and the settlement data was manually measured using a level. The data was calibrated with the automated data of the settlement monitoring device to ensure the accuracy of deformation rate measurement. In terms of structural design, the drilling holes of the geological exploration equipment need to avoid drainage blind ditches and subsequent filling areas. The sensors of the settlement monitoring device need to be fixed on the concrete base on the surface of the compacted layer to avoid mechanical disturbance during the filling process. Through the above construction method, the timing of burying the drainage pipe can be dynamically determined according to the actual bearing capacity and deformation state of the foundation. This can prevent the drainage pipe from being damaged due to excessive load due to premature burial, and avoid failure of the drainage system due to late burial, effectively improving the reliability and adaptability of the roadbed drainage structure under complex terrain.

[0083] This pre-set threshold determination method, using dual indicators, significantly improves the accuracy and rationality of drainage pipe placement. Setting a threshold between 70% and 80% of the foundation's bearing capacity mutation point avoids both the problem of insufficient foundation bearing capacity caused by premature drainage pipe placement and the drawbacks of excessively long drainage paths and reduced drainage efficiency caused by late placement. Real-time deformation rate monitoring, combined with stability condition determination, dynamically captures the foundation's consolidation state. When the deformation rate is consistently less than 0.5 mm / day, it indicates that initial foundation settlement has largely completed. Laying out drainage pipes at this point effectively minimizes the impact of later settlement on the drainage system and prevents pipe breakage or blockage due to uneven settlement. The incremental threshold setting ensures that the optimal placement timing can be gradually approached even under complex geological conditions. Through layered filling and dynamic adjustment, the drainage pipe placement elevation is more closely aligned with the foundation's actual bearing capacity and deformation characteristics. This approach effectively improves the reliability and durability of the roadbed drainage system, reduces the risk of roadbed damage caused by poor drainage, extends the road's service life, and reduces ongoing maintenance costs.

[0084] In another technical solution, the specific method of dynamically adjusting the paving thickness of the graded gravel layer through elevation control piles is as follows:

[0085] Elevation control piles are set at intervals of 5 to 8 meters along the longitudinal axis of the roadbed surface. The elevation of the top of the elevation control piles is consistent with the design elevation of the graded gravel layer.

[0086] As the paver moves, the vertical distance between the surface of the paved gravel layer and the top of the elevation control pile is measured in real time using a laser rangefinder;

[0087] When the measured vertical distance exceeds the designed paving thickness range of -10mm to +15mm, the paver's hydraulic control system will synchronously adjust the scraper opening and travel speed;

[0088] After the dynamic adjustment is completed, a continuous elevation control reference surface is formed on the surface of the graded gravel layer, and its longitudinal flatness error is controlled within the range of ±5mm / 10m.

[0089] In this technical solution, elevation control piles are set up at intervals of 6m along the longitudinal axis of the roadbed surface. The elevation control piles can be made of steel pipes or reinforced concrete piles with a diameter of 25mm, and their top elevation is consistent with the design elevation of the graded gravel layer. The elevation control piles are set up using a total station for precise measurement and positioning to ensure that the error in their top elevation does not exceed ±3mm. During the movement of the paver, a laser rangefinder installed in front of the paver screed measures the vertical distance between the surface of the paved gravel layer and the top of the elevation control pile in real time. The laser rangefinder can be a model with a measurement accuracy of ±2mm, and the measurement frequency is set to 5 times per second to ensure the real-time nature of the data. When the measured vertical distance exceeds the range of -8mm to +12mm of the designed paving thickness, the hydraulic control system of the paver synchronously adjusts the scraper opening and travel speed. For example, if the measured distance is 8mm less than the designed thickness, the hydraulic control system increases the scraper opening by 5mm and reduces the paver's travel speed by 0.3m / min. If the measured distance is 12mm greater than the designed thickness, the scraper opening is reduced by 6mm and the travel speed is increased by 0.4m / min. This dynamic adjustment process is implemented using a PID controller. The controller parameters are optimized based on field test data, with the proportional coefficient set to 0.8, the integral coefficient to 0.2, and the differential coefficient to 0.1. After dynamic adjustment, a continuous elevation control datum surface is formed on the surface of the graded gravel layer. Using a level, longitudinal flatness errors are checked by measuring five points in each section at 10m intervals. The longitudinal flatness error of the elevation control datum surface is within ±5mm / 10m. For functional testing, a 200m test section was selected, and the paving thickness was measured before and after dynamic adjustment to compare and analyze thickness uniformity. In terms of structural design, elevation control piles must be buried at least 500mm into the roadbed soil to ensure stability. The laser rangefinder must be mounted on the paver's rigid support to prevent vibration from affecting measurement accuracy. This dynamic paving thickness adjustment method effectively improves the smoothness and thickness uniformity of the graded gravel layer, providing a good foundation for subsequent pavement structure construction.

[0090] This technical solution significantly improves paving accuracy and surface quality by installing elevation control stakes on the roadbed surface and combining laser ranging with a hydraulic control system to dynamically adjust the paving thickness of the graded gravel layer. Elevation control stakes are placed at intervals of 5 to 8 meters and precisely positioned at their elevations, providing a continuous reference for paving operations. This avoids the discrete errors associated with traditional manual measurement and ensures that the elevations of each section of the graded gravel layer meet design requirements. A laser rangefinder monitors the paving thickness in real time. When the measured vertical distance exceeds the range of -10mm to +15mm, the hydraulic system synchronously adjusts the scraper opening and paver speed. This dynamic feedback mechanism effectively offsets thickness deviations caused by factors such as longitudinal slope changes and uneven filler particle distribution, significantly improving paving thickness uniformity. The resulting elevation control datum surface maintains a longitudinal flatness tolerance of ±5mm / 10m, providing a stable support foundation for the pavement structure. The uniformly graded gravel layer not only enhances surface drainage and reduces the risk of subgrade softening caused by rainwater retention, but also mitigates the impact of differential settlement on the superstructure by optimizing stress distribution. This method avoids the lag inherent in traditional paving processes, which rely on manual experience and adjustments. It achieves automated and precise control of the paving process, effectively improving the quality of subgrade surface construction in complex terrain and laying the foundation for the long-term, stable operation of subsequent projects.

[0091] In another technical solution, the method further includes: setting an elevation re-measurement point behind the paver and using a dynamic compaction tester to obtain compaction data of the adjusted area;

[0092] When the compaction data is lower than 95% of the design value, control the vibratory roller to roll the corresponding area 1 to 2 times more;

[0093] During additional rolling, the exciting force of the vibratory roller is increased by 10%~15%, and the rolling path forms an intersection angle of 30°~45° with the original path.

[0094] In this technical solution, an elevation re-measurement point is set 3 to 5 meters behind the paver, and a detection section is arranged every 10 to 15 meters along the longitudinal direction of the roadbed. Each section has a measurement point at the center line and 20 cm from the edges on both sides. A portable dynamic compaction tester, such as a drop hammer compaction tester or a nuclear density tester, can be used at the re-measurement point. It is fixed on a movable detection bracket. The height of the bracket is flush with the bottom surface of the paver screed. Ensure that the detector probe is vertically aligned with the surface of the paved graded gravel layer to obtain compaction data in real time. The detector is connected to the on-site control system via a data cable or a wireless transmission module, and the measured compaction value is fed back to the control terminal in real time. When the dynamic compaction tester shows that the compaction data of a certain area is lower than 95% of the design value, the control terminal automatically marks the area and dispatches a vibratory roller for additional compaction. Vibratory rollers can be selected with models that have an exciting force adjustment function. After receiving the command, the operator manually or automatically increases the exciting force by 12% (within the middle range of 10% to 15%). For example, when the original exciting force is 250kN, it is adjusted to 280kN. At the same time, the rolling path is adjusted to a 40° cross angle with the original rolling direction (within the range of 30° to 45°) to ensure that the weak areas of the original rolling are covered. The number of additional rolling passes is controlled to 1 pass. If the compaction degree after the first rolling is still not up to standard, another pass will be added. In the functional test, a test section with a length of 150m was selected, and 5 test points were randomly selected in the dynamic adjustment area and the non-adjustment area, and the compaction degree was compared using the sand injection method. The results show that the compaction degree of the area after the additional rolling meets the design requirements. In terms of structural design, the dynamic compaction tester's bracket must have a shock-absorbing function to prevent the paver's vibration from affecting test accuracy. The vibratory roller's steering system must support precise angle control to ensure that the cross-rolling path meets the set requirements. This construction method can promptly detect and address any insufficient compaction that may occur during the paving process, effectively improving the overall density of the graded gravel layer, providing a uniform and stable load-bearing foundation for the roadbed surface, and reducing the risk of subsequent settlement caused by localized compaction defects.

[0095] This technical solution effectively improves the construction quality of graded gravel layers by establishing elevation retest points behind the paver and combining dynamic compaction testing with additional compaction. By placing retest points 3-5 meters behind the paver and using a dynamic compaction meter to capture real-time data, this method promptly identifies areas of insufficient compaction due to paving adjustments or filler characteristics, avoiding the missed detections associated with traditional spot checks and ensuring comprehensive and timely compaction testing. When the compaction level falls below 95% of the design value, the vibratory roller is controlled to increase the excitation force by 10-15% and perform additional compaction at a 30-45° cross-rolling angle, specifically enhancing the compaction of weak areas. This cross-rolling path fills the gaps left by the original rolling track, addressing the compaction blind spots at the junction of adjacent rolling sections. The increased excitation force adapts to the compaction requirements of different fillers, ensuring effective additional compaction. This dynamic feedback mechanism avoids the blindness of empirical recompaction and enables precise repair of compaction defects. The synergistic effect of the above measures has effectively improved the overall compaction uniformity of the graded gravel layer, provided a stable bearing foundation for the roadbed surface, reduced the risk of differential settlement caused by insufficient local compaction, ensured the coordinated stress-bearing performance of the roadbed and subsequent pavement structure layers, and extended the service life of the road project.

[0096] In another technical solution, the specific method of the reinforcement treatment in step 5 includes:

[0097] When the elevation difference between adjacent monitoring points exceeds 10-15 mm, a circular difference area with a radius of 2-3 m is delineated with the point with the maximum elevation difference as the center;

[0098] In the difference area, the internal structure of the roadbed is scanned using ground penetrating radar. If the porosity is greater than 20% or the filler layer interface misalignment exceeds 50mm, high-pressure rotary grouting is used for reinforcement, and the grouting pressure is controlled at 0.8~1.2MPa.

[0099] If the fill density is detected to be 5% to 8% lower than the design value, the surface fill in the difference area shall be removed to the stable layer, and the fill shall be re-filled in layers and re-compacted with a vibratory roller with a 10% to 15% higher excitation force for 3 to 4 times;

[0100] After the processing is completed, the monitoring points in the difference area are densely distributed to 1 / 2 of the original spacing, and the monitoring cycle is shortened to 1 / 3 of the original cycle, until the fluctuation range of the monitoring data is less than 2mm for three consecutive times.

[0101] In this technical solution, when the elevation difference between adjacent monitoring points exceeds 12mm (within the 10-15mm range), a circular differential zone with a radius of 2.5m (within the 2-3m range) is delineated centered on the point with the maximum elevation difference. Within this differential zone, an optional ground-penetrating radar (GPR) device is used to scan the internal structure of the roadbed. The GPR antenna moves at a constant speed along the roadbed surface, with a scanning frequency set to 200MHz. It can penetrate the filler layer to detect porosity and the state of the stratified interfaces. If a porosity of 22% (exceeding the 20% threshold) or a 60mm misalignment of the filler interface (exceeding the 50mm threshold) is detected, it is considered a structural defect and reinforcement is initiated using high-pressure jet grouting. A twin-tube jet grouting machine can be used for grouting, with a controlled grouting pressure of 1.0MPa (within the 0.8-1.2MPa range) to ensure uniform penetration of the grout into the defective area. If the ground-penetrating radar detects that the fill density is 6% lower than the design value (within the range of 5%-8%), the surface fill in the discrepancy area is manually removed to the stable layer. The removal depth is determined by the density test results and is generally 30-50 cm. After removal, the roadbed fill is re-applied in layers, with each layer controlled to a thickness of 20-30 cm. A vibratory roller is used for additional compaction. During additional compaction, the vibratory roller's excitation force is increased by 12% (within the range of 10%-15%). For example, if the original excitation force is 200 kN, it can be adjusted to 224 kN. The rolling path should be at a 40° intersection angle (within the range of 30°-45°) with the original filling direction. Three additional compaction passes (within the range of 3-4) are performed to ensure that the fill density meets the standard. After the reinforcement treatment was completed, settlement monitoring points were re-established in the differentially settled areas. The original monitoring spacing of 10m vertically and 8m horizontally was shortened to 5m vertically and 4m horizontally (half the original spacing), and the monitoring cycle was shortened from 7 days to 2 days (one-third the original cycle). Elevation data was collected using a total station at the new interval until the fluctuation range of the monitoring data was less than 2mm for three consecutive times. During functional testing, the treated areas were re-measured for compaction using sand injection and the internal structure was re-inspected using ground-penetrating radar to ensure the effectiveness of the reinforcement. In terms of structural design, the ground-penetrating radar antenna was maintained at a height of 5-10cm above the roadbed surface to avoid contact damage. The verticality error of the high-pressure rotary jet grouting pipe was controlled within 1% to ensure grouting uniformity. This reinforcement treatment method enables precise targeting of different types of roadbed defects, effectively improving the bearing capacity of areas with differential settlement and ensuring the overall stability of the roadbed.

[0102] This technical solution's reinforcement treatment method effectively improves the repair of differential settlement areas in the roadbed through graded assessment and targeted measures. When the elevation difference between adjacent monitoring points exceeds 10-15mm, a circular area with a radius of 2-3m centered on the point with the maximum elevation difference can accurately locate the core area of ​​differential settlement, avoiding blind reinforcement across large areas and improving treatment efficiency. Ground-penetrating radar scanning technology penetrates the roadbed surface, clearly identifying defects such as excessive porosity, misaligned filler layers, or insufficient compaction, providing an intuitive basis for selecting reinforcement solutions. For structural defects with porosity greater than 20% or misaligned interlayers exceeding 50mm, high-pressure rotary jet grouting, controlled at a pressure of 0.8-1.2MPa, ensures uniform grouting and cementation of misaligned interfaces, effectively enhancing local bearing capacity. For compaction defects with compaction levels 5-8% below the design value, surface filler is removed, followed by re-filling in layers and increasing the excitation force to compensate for the compaction. This fundamentally addresses insufficient filler density and prevents subsequent settlement. After reinforcement is complete, monitoring points are increased to half their original spacing and the monitoring cycle is shortened. This allows for real-time tracking of settlement dynamics in the treated area, ensuring that regular monitoring is resumed only after three consecutive monitoring data fluctuations are less than 2 mm, thus forming a closed-loop quality control system. This approach avoids the blindness of traditional unified reinforcement and implements a precise "detection-diagnosis-repair-monitoring" process. This significantly improves the bearing stability of differential settlement areas, reduces the risk of recurrence of roadbed defects, ensures the long-term uniform stress-bearing performance of the entire fill, and effectively extends the safe service life of roadbeds in complex mountainous terrain.

[0103] In another technical solution, it further includes:

[0104] If there are signs of slope slip in the differential area, a bidirectional geogrid with a tensile strength of 100-150 kN / m will be laid on the slope surface and fixed to the deep stabilization layer of the slope with L-shaped anchors at a depth of 1.5-2 m.

[0105] The installation sequence of the L-shaped anchor rods is to construct them row by row from top to bottom. The installation interval of the anchor rods in the same row is 1.2 to 1.5 times the length of the anchor rods, and the minimum spacing shall not be less than 1.8m. The node between the tail of the anchor rod and the geogrid shall be locked by fasteners.

[0106] In this technical solution, if signs of slope slippage appear in the differential area, such as microcracks or localized soil swelling, the slope surface in the slip zone is first cleaned to remove loose soil, loose fill, and vegetation, exposing the solid soil layer. Subsequently, horizontal lines are laid out along the slope surface at intervals of 1.8 to 2.5 meters (determined by the anchor depth) to mark the installation locations for L-shaped anchors. Bidirectional geogrids can be made of pre-made polypropylene, with a tensile strength of 120 kN / m (within the 100 to 150 kN / m range), effectively resisting lateral tension in the slope soil. L-shaped anchors can be made from threaded rebar with a diameter of 20 to 25 mm. The vertical section of the anchor is buried at a depth of 1.8 m (within the 1.5 to 2 m range), and the horizontal section is 30 to 50 cm long, forming a stable "L"-shaped anchoring structure. Anchor bolts are installed row by row from top to bottom. The spacing between anchor bolts in a row is 1.2 times the bolt length (e.g., 2.16m for anchor bolts buried at a depth of 1.8m), and must meet the minimum spacing requirement of 1.8m. Vertical holes are drilled at the marked locations using a drill rig, with a depth slightly greater than the vertical length of the anchor bolt (approximately 1.85m). After cleaning the holes, L-shaped anchor bolts are inserted into the holes and secured with M20 cement mortar. After the anchor bolts have consolidated, the bidirectional geogrid is deployed longitudinally along the slope, aligning the grid nodes with the anchor bolt tails. Metal U-shaped fasteners secure the grid nodes to the anchor bolt tails, ensuring a secure connection between the grid and the anchor bolts. During installation, the grid is kept flat and tensioned appropriately to avoid wrinkles or loosening. During functional testing, the installed L-shaped anchor bolts are subjected to pullout tests to verify that their pullout resistance meets the design requirements (minimum 80kN) and to verify the secure connection between the U-shaped fasteners and the grid nodes. In terms of structural design, the horizontal section of the anchor rod needs to face inward from the slope, maintaining an inclination of 10-15 degrees with the slope surface to enhance the anchoring effect on the deep stabilization layer; the overlap width of the bidirectional geogrid should be no less than 20 cm to ensure continuous force between adjacent grids. Through this reinforcement method, the bidirectional geogrid and L-shaped anchor rods work together to transfer the shallow sliding force of the slope to the deep stabilization soil layer, effectively improving the shear strength of the potential slip surface. Combined with the construction sequence of layered anchoring, the overall stability of the slope is gradually enhanced, the risk of slip caused by differential settlement is reduced, and the safety performance of the roadbed slope under long-term load is guaranteed.

[0107] This technical solution utilizes bidirectional geogrids combined with L-shaped anchors to effectively enhance slope stability when signs of slope slip are present in differential areas. The bidirectional geogrids are constructed from materials with a tensile strength of 100-150 kN / m, capable of withstanding lateral forces in the slope soil, suppressing shallow slip and enhancing the integrity of the slope surface. The L-shaped anchors are buried 1.5-2 meters deep, with their anchor ends located in the deep stabilization layer of the slope. This transfers the tensile forces exerted on the geogrid to the deeper soil layers, significantly increasing the shear strength of the potential slip surface and preventing further slippage. Anchors are installed in rows from top to bottom, with spacing within each row at 1.2-1.5 times the anchor length and no less than 1.8 meters. This ensures even distribution of anchoring force and avoids uneven stress caused by overly close or sparse spacing. The anchor tails are locked to the geogrid nodes with fasteners, forming a reliable mechanical connection. This allows the geogrid and slope soil to deform synergistically, effectively distributing areas of stress concentration. This reinforcement method precisely targets signs of slippage and, through the combination of deep anchoring and surface reinforcement, fundamentally improves the slope's anti-slip ability, reduces the risk of secondary disasters caused by differential settlement, and ensures the long-term stability of the roadbed slope under complex load and environmental conditions.

[0108] In another technical solution, the grouting pressure of the high-pressure rotary jet grouting method is dynamically adjusted according to the permeability coefficient of the soil in different areas:

[0109] When the soil permeability coefficient k≥1×10 -4 cm / s, the grouting pressure is controlled at 0.8~1.0MPa, the spacing between grouting holes is 0.8m×0.8m to 1m×1m, and the grouting speed is 15~20L / min;

[0110] When the soil permeability coefficient is 1×10 -6 cm / s≤k<1×10 -4 cm / s, the grouting pressure is controlled at 1.0~1.2MPa, the spacing between grouting holes is 0.6m×0.6m to 0.8m×0.8m, and the grouting speed is 10~15L / min;

[0111] When the soil permeability coefficient k < 1 × 10 -6 cm / s, a pre-cracking process is used before grouting. The spacing between pre-cracking holes is 0.5-0.7 times the spacing between grouting holes. The pre-cracking pressure is applied in stages. The initial pressure is 0.8-1.0 times the grouting pressure. The pressure is increased by 0.2 MPa for 2 minutes each time. The final pressure does not exceed 1.2 times the grouting pressure.

[0112] After grouting is completed, the slurry consolidation state is monitored by a pore water pressure sensor. If the pore water pressure dissipation rate is less than 30% of the initial value within 24 hours after grouting, slurry is injected into the adjacent hole position with an injection pressure of 80% to 90% of the original pressure.

[0113] In this technical solution, before reinforcing the differential area, the soil permeability coefficient k is first determined by indoor permeability test or on-site pumping test. -4 When the pressure is 0.15 MPa, the grouting speed is controlled at 18L / min (15-20L / min). A pressure sensor can be installed on the top of the grouting pipe to monitor the changes in grouting pressure in real time to ensure that the parameters meet the design requirements. The grouting material can be P.O42.5 ordinary Portland cement, and the water-cement ratio is 0.8:1 to ensure the fluidity of the slurry. When 1×10 -6 cm / s≤k<1×10 - 4 cm / s, adjust the grouting equipment pressure to 1.1MPa (within the range of 1.0-1.2MPa), reduce the grouting hole spacing to 0.7m×0.7m (within the range of 0.6m×0.6m to 0.8m×0.8m), and reduce the grouting speed to 12L / min (within the range of 10-15L / min). -6 cm / s, a pre-cracking process is required: the spacing between pre-cracking holes is set to 0.6 times the spacing between grouting holes (within a range of 0.5-0.7 times). The initial pre-cracking pressure is 80% of the grouting pressure (e.g., 0.8 MPa for a grouting pressure of 1.0 MPa). The pressure is then increased by 0.2 MPa every two minutes and stabilized, with the final pressure not exceeding 1.2 times the grouting pressure. During the pre-cracking process, the pre-cracking pipes are spaced apart from the grouting pipes to ensure that the pre-cracking holes form a permeability channel for subsequent grouting. After grouting is completed, pore water pressure sensors are embedded between adjacent grouting holes at a depth consistent with the grouting section. These sensors are connected to an on-site data acquisition system via a data cable to monitor the grout consolidation status in real time. If the pore water pressure dissipation rate is less than 30% of the initial value within 24 hours after grouting, the supplementary grouting process is initiated, with the supplementary injection pressure controlled at 85% of the original grouting pressure (within a range of 80%-90%). The supplementary grouting material is the same as that used in the initial grouting to ensure a dense grouting filling in the reinforced area. During functional testing, on-site grouting tests can be conducted in typical geological areas. Coring can be performed to test the strength and uniformity of the reinforced soil, allowing grouting parameters to be adjusted to meet design requirements. Structurally, the grouting pipe must remain vertical, with a verticality error controlled within 1%. Pressure sensors require regular calibration to ensure data accuracy. This construction method allows the grouting process to be dynamically adjusted based on the soil's permeability characteristics, improving slurry diffusion uniformity and ensuring reinforcement effectiveness under varying geological conditions.

[0114] This technical solution uses high-pressure rotary jet grouting to regulate grouting parameters by graded adjustment of the soil permeability coefficient, significantly improving the reinforcement effect under different geological conditions. For soils with high permeability coefficients, lower pressure and larger hole spacing avoid excessive loss of slurry, ensuring the formation of a continuous reinforcement body in the permeable layer; for soils with medium and low permeability coefficients, increasing pressure and reducing hole spacing enhances the slurry's permeability and improves soil density. For soils with extremely low permeability coefficients, the pre-cracking process breaks down the compactness of the soil structure through staged pressurization, creating channels for slurry diffusion and avoiding reinforcement blind spots caused by insufficient pressure. Post-grouting pore water pressure monitoring and supplementary grouting mechanisms ensure that the slurry fully fills the pores and consolidates, avoiding the impact of local slurry loss on the reinforcement effect. This dynamic adjustment method reduces the blindness of traditional uniform parameter grouting, significantly improves the uniformity of slurry diffusion, and makes the bearing capacity of the reinforced area more balanced, effectively reducing the risk of recurrence of differential settlement of the roadbed and ensuring the long-term reliability of the reinforcement project under complex geological conditions.

[0115] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. A roadbed construction method for crossing a V-shaped valley area, characterized in that: The following steps are involved: Step 1: dig a trench longitudinally along the roadbed at the bottom of the V-shaped valley and lay a permeable geotextile, then fill it with gravel to form a drainage blind ditch. The top of the drainage blind ditch is covered with permeable geotextile and the edges on both sides extend to the roadbed fill boundary; The roadbed fill material is laid layer by layer above and on both sides of the blind drainage ditch, covering the entire roadbed cross section. After each layer is filled, it is rolled by a vibratory roller according to a preset compaction path. The direction of travel of the vibratory roller is parallel to the longitudinal axis of the roadbed, and the overlapping width of adjacent rolling wheel tracks is 1 / 3 to 1 / 2 of the wheel width. Step 2: After each two layers of roadbed fill are completed, a unidirectional geogrid is deployed longitudinally on the slope surface of the roadbed. The laying direction of the unidirectional geogrid is consistent with the longitudinal direction of the roadbed and is vertically inserted into the compacted fill layer through U-shaped steel anchors. The horizontal spacing of the U-shaped steel anchors is 1.5-2m and aligned with the overlap area of ​​the geogrid. Step 3: When the roadbed filling height reaches a preset threshold, multiple drainage pipes are pre-buried horizontally below the top surface of the roadbed. The inlet ends of the drainage pipes are connected to the drainage blind ditch through inclined connecting pipes, and the outlet ends extend to the outside of the roadbed slope. The water-filtration geotextile wrapped around the drainage pipes and the permeable geotextile of the drainage blind ditch form a continuous drainage interface; The method for determining the preset threshold value includes the following steps: Through geological exploration, the foundation bearing capacity data of different depths in the V-shaped valley section are obtained. When the cumulative thickness of the roadbed fill layer reaches 70% to 80% of the depth corresponding to the foundation bearing capacity mutation point, it is determined to be the preset threshold trigger point; During the filling process, a settlement monitoring device is used to measure the compression deformation rate of the filled layer in real time. When the deformation rate is less than 0.5 mm / d for three consecutive days, the preset threshold judgment condition is triggered synchronously; If the sudden change point of foundation bearing capacity and the stable deformation rate conditions are met at the same time, the buried elevation of the horizontal drainage pipe is located 1.2~1.8m below the top of the current filling layer; If the two conditions are not met at the same time, the filling will continue until the thickness of the next layer reaches the incremental threshold of the depth corresponding to the mutation point of the foundation bearing capacity. The incremental threshold is 1.2 to 1.5 times the thickness of the single layer of filling. Step 4: After the roadbed is filled to the designed elevation, a graded gravel layer is evenly spread on the roadbed surface and leveled. The paving thickness of the graded gravel layer is dynamically adjusted by elevation control piles. After paving is completed and static curing is carried out, intercepting ditches are excavated at the foot of the slopes on both sides of the roadbed. A concrete cushion is laid at the bottom of the intercepting ditch, and the longitudinal slope of the intercepting ditch is consistent with the drainage direction of the roadbed; Step 5: After the self-fill is completed, an array of settlement monitoring points is laid out on the roadbed surface. The monitoring points are distributed in a grid along the longitudinal and transverse directions of the roadbed, and elevation data is collected at a fixed period using a total station. When the elevation difference between adjacent monitoring points exceeds a set threshold, reinforcement treatment is carried out in the corresponding area; Among them, the specific methods of reinforcement treatment include: When the elevation difference between adjacent monitoring points exceeds 10 mm, a circular difference area with a radius of 2 to 3 m is delineated with the point with the maximum elevation difference as the center; In the difference area, the internal structure of the roadbed is scanned using ground penetrating radar. If the porosity is greater than 20% or the filler layer interface misalignment exceeds 50mm, high-pressure rotary grouting is used for reinforcement, and the grouting pressure is controlled at 0.8~1.2MPa. If the fill density is detected to be 6% lower than the design value, the surface fill in the difference area shall be removed to the stable layer, and the fill shall be re-filled in layers and re-compacted with a vibratory roller with a 10% to 15% higher excitation force for 3 to 4 times; After the processing is completed, the monitoring points in the difference area are densely distributed to 1 / 2 of the original spacing, and the monitoring cycle is shortened to 1 / 3 of the original cycle, until the fluctuation range of the monitoring data is less than 2mm for three consecutive times.

2. The roadbed construction method for crossing a V-shaped valley area according to claim 1, characterized in that: Piezoelectric dynamic compaction sensors are arranged inside the steel wheel of the vibratory roller at intervals of 200 to 300 mm to collect real-time waveform data of the reaction force of the filler during rolling; The IoT control platform performs spectrum analysis on waveform data to extract the energy proportion of characteristic frequency segments. When the energy proportion is lower than the set threshold range of 65%, it is determined that the compaction degree is insufficient. If the compaction data of three consecutive rolling sections are all below the lower threshold, the roller will be controlled to automatically increase the vibration frequency of the current rolling section by 2 to 4 Hz and perform 1 to 2 additional rolling passes; If the energy ratio exceeds the upper threshold, the vibration frequency will be reduced by 1~2Hz, and the number of rolling times in the subsequent rolling section will be reduced by 1.

3. The roadbed construction method for crossing a V-shaped valley area according to claim 2, characterized in that: At the intersection of adjacent rolling sections, differential positioning technology is used to control the roller wheel track overlap width to increase by 50-100mm, and the vibration frequency in this area is simultaneously increased by 1-3Hz; After every 100-150m of rolling work, the IoT platform generates a compaction heat map. Areas with a compaction dispersion coefficient greater than 0.15 are marked as re-compaction areas, and fan-shaped paths are used for re-compaction. The dense rolling of the fan-shaped path includes rolling in circles along concentric arc tracks with a radius of 1 to 3 meters, with the center of the re-compacting area as the center of the circle, and the spacing between adjacent arcs is 1 / 2 to 2 / 3 of the roller wheel width.

4. The roadbed construction method for crossing a V-shaped valley area according to claim 1, characterized in that: The specific method for dynamically adjusting the paving thickness of the graded gravel layer through the elevation control piles is as follows: Elevation control piles are set at intervals of 5 to 8 meters along the longitudinal axis of the roadbed surface. The elevation of the top of the elevation control piles is consistent with the design elevation of the graded gravel layer. As the paver moves, the vertical distance between the surface of the paved gravel layer and the top of the elevation control pile is measured in real time using a laser rangefinder; When the measured vertical distance exceeds the designed paving thickness range of -10mm to +15mm, the paver's hydraulic control system will synchronously adjust the scraper opening and travel speed; After the dynamic adjustment is completed, a continuous elevation control reference surface is formed on the surface of the graded gravel layer, and its longitudinal flatness error is controlled within the range of ±5mm / 10m.

5. The roadbed construction method for crossing a V-shaped valley area according to claim 4, characterized in that: Further including: Set up an elevation re-measurement point behind the paver and use a dynamic compaction tester to obtain compaction data for the adjusted area; When the compaction data is lower than 95% of the design value, control the vibratory roller to roll the corresponding area 1 to 2 times more; During additional rolling, the exciting force of the vibratory roller is increased by 10%~15%, and the rolling path forms an intersection angle of 30°~45° with the original path.

6. The roadbed construction method for crossing a V-shaped valley area according to claim 1, characterized in that: Further including: If there are signs of slope slip in the differential area, a bidirectional geogrid with a tensile strength of 100-150 kN / m will be laid on the slope surface and fixed to the deep stabilization layer of the slope with L-shaped anchors at a depth of 1.5-2 m. The installation sequence of the L-shaped anchor rods is to construct them row by row from top to bottom. The installation interval of the anchor rods in the same row is 1.2 to 1.5 times the length of the anchor rods, and the minimum spacing shall not be less than 1.8m. The node between the tail of the anchor rod and the geogrid shall be locked by fasteners.

7. The roadbed construction method for crossing a V-shaped valley area according to claim 1, characterized in that: The grouting pressure of the high-pressure rotary jet grouting method is dynamically adjusted according to the permeability coefficient of the soil in different areas: When the soil permeability coefficient k≥1×10 -4 cm / s, the grouting pressure is controlled at 0.8~1.0MPa, the spacing between grouting holes is 0.8m×0.8m to 1m×1m, and the grouting speed is 15~20L / min; When the soil permeability coefficient is 1×10 -6 cm / s≤k<1×10 -4 cm / s, the grouting pressure is controlled at 1.0~1.2MPa, the spacing between grouting holes is 0.6m×0.6m to 0.8m×0.8m, and the grouting speed is 10~15L / min; When the soil permeability coefficient k < 1 × 10 -6 cm / s, a pre-cracking process is used before grouting. The spacing between pre-cracking holes is 0.5-0.7 times the spacing between grouting holes. The pre-cracking pressure is applied in stages. The initial pressure is 0.8-1.0 times the grouting pressure. The pressure is increased by 0.2 MPa for 2 minutes each time. The final pressure does not exceed 1.2 times the grouting pressure. After grouting is completed, the slurry consolidation state is monitored by a pore water pressure sensor. If the pore water pressure dissipation rate is less than 30% of the initial value within 24 hours after grouting, slurry is injected into the adjacent hole position with an injection pressure of 80% to 90% of the original pressure.