Comprehensive reinforcement construction method for roadbed and pavement of settlement section of mountain road

Abstract

The invention discloses a comprehensive reinforcement construction method for a roadbed and a pavement of a settlement section of a mountainous road. The method comprises the following steps: geological exploration and analysis; subgrade layering treatment and reinforcement are conducted, specifically, subgrade foundation treatment is conducted firstly, then subgrade filling is conducted, and subgrade foundation treatment comprises at least one treatment mode of replacement filling, cement mixing piles, CFG piles, steps, gravel blind ditches and drainage intercepting ditches; subgrade filling comprises raw material selection, layered filling, geogrid and common ramming reinforcement; optimizing construction of a pavement structure: optimizing construction of a subbase layer, a base layer and a surface layer; and intelligent dynamic monitoring is carried out. The method has the beneficial effects that the settlement section of the mountain road is comprehensively treated by adopting geological exploration and various reinforcement measures, all links are mutually matched and synergistic from foundation treatment to roadbed filling and water interception and drainage to pavement structure optimization, the stability and durability of the roadbed and the pavement can be effectively improved, and the problem of settlement of the mountain road is solved.

Description

Technical Field

[0001] The present application belongs to the technical field of road engineering construction, and specifically relates to a comprehensive reinforcement construction method for the subgrade and pavement of a mountain road settlement section, which is suitable for preventing and controlling the subgrade and pavement settlement of geologically unstable mountain road sections. The combined reinforcement technology is used to improve the stability of the subgrade, prevent uneven subgrade settlement, and extend the service life of the road. Background Art

[0002] Mountainous areas have complex terrain and poor geological conditions, often accompanied by unfavorable geological conditions such as weak soil layers, rock fracture zones, and high and steep slopes. During road construction, settlement problems are more prominent. Uneven settlement of the roadbed in the settlement section of mountain roads can lead to road cracking, depressions, water damage and other defects, which not only affect driving comfort but also pose serious safety hazards. At present, the treatment methods for settlement sections of mountain roads mostly use a single reinforcement method, such as grouting reinforcement of the foundation, geotextiles, replacement or strengthening the pavement structure. These methods are difficult to fundamentally solve the problems of settlement sections of mountain roads and cannot meet the requirements of mountain roads for roadbed and pavement stability and durability. Therefore, there is an urgent need for a comprehensive reinforcement construction method that can effectively solve the problems of settlement sections of mountain roads. Summary of the Invention

[0003] The purpose of this application is to provide a comprehensive reinforcement construction method for the subgrade and pavement of a mountain road settlement section. Aiming at the problem that the subgrade and pavement reinforcement technology in the mountain road settlement section is single and cannot dynamically deal with the uneven subgrade, the application mainly optimizes and improves the soft foundation treatment, subgrade backfill, subgrade reinforcement technology, intelligent monitoring, pavement structure and other aspects, forming a comprehensive subgrade reinforcement construction method of "subgrade layered reinforcement + intelligent dynamic monitoring + pavement structure optimization" in the mountain road settlement section, solving the problem of uneven settlement of the subgrade and pavement in the mountain road settlement section. The application has the characteristics of precise foundation treatment, good subgrade integrity, integration of interception and drainage system with subgrade, efficient and accurate intelligent monitoring, etc.

[0004] The purpose of this application is achieved through the following technical solutions:

[0005] A comprehensive reinforcement construction method for roadbed and pavement in a mountainous road settlement section comprises the following steps:

[0006] Step S01, geological exploration and analysis;

[0007] Step S02, roadbed reinforcement by layering: first, perform roadbed foundation treatment, then perform roadbed filling. Roadbed foundation treatment includes at least one of replacement filling, cement mixing piles, CFG piles, steps, gravel blind ditches, and intercepting drainage ditches. Roadbed filling includes raw material selection, layered filling, geogrid reinforcement, and general tamping reinforcement.

[0008] Step S03, pavement structure optimization construction: including optimization construction of subbase, base layer and surface layer;

[0009] During the construction process of step S02 and step S03 and after the construction is completed, intelligent dynamic monitoring is carried out.

[0010] Furthermore, in the step S01, geological radar, drilling, and measurement are used to survey the settlement section of the mountain road to obtain information on the geological structure, groundwater level, geological core samples, foundation bearing capacity, and settlement causes, and the settlement degree and development trend of the settlement section are evaluated, and different settlement areas are divided; according to the different settlement areas divided according to the geological and hydrological conditions of the mountain settlement section roadbed, the original topography, the original foundation bearing capacity, and the roadbed filling height, the corresponding treatment method is selected through comprehensive analysis to form a composite foundation.

[0011] Furthermore, in step S02, the backfill method is used for shallow soft foundations with a depth of less than 3 meters. The soft soil layer is excavated and replaced with graded crushed stone and gravel materials. The materials are spread and leveled in layers using an excavator in conjunction with a scraper. The materials are then compacted in layers using a vibratory roller of not less than 18 tons. The thickness of each layer does not exceed 30 cm, and the compaction degree is not less than 96%.

[0012] Cement mixing piles: For deep soft foundations with a depth greater than 3 meters and a fill height less than 15 meters, high-pressure rotary jet grouting is used. RTK is used to arrange pile positions at intervals of no more than 2 meters. High-pressure spray pile driving machinery is then used to drill holes in the foundation. Cement slurry is sprayed at high pressure and mixed with the soil to form a cement-soil reinforcement. After the cement mixing piles have passed inspection, a graded gravel cushion layer at least 50 cm thick is placed on top of the piles. The graded gravel cushion layer is then spread, leveled, rolled, and compacted in layers.

[0013] CFG piles: For deep soft foundations with a soft foundation depth greater than 3 meters and a fill height greater than 15m, the spiral drilling method is adopted, and the pile positions are arranged at intervals of no more than 1.7m using RTK. Then, a high-pressure spiral pile driving machine is used to drill holes in the foundation and pour the mixture to form a complete pile body. After the pile body is accepted, a small excavator is used in combination with manual labor to dig out the pile head, a level is used to measure and lay out the designed elevation position line of the pile head, and a cutting machine is used to cut off the excess pile head; each CFG pile is provided with a reinforced concrete pile cap at the top of the pile, and the pile cap formwork is made on-site using a wooden formwork. The pile cap steel bars prefabricated in the steel bar yard are placed in the formwork. After acceptance, concrete pouring and maintenance work are carried out. A small excavator is used to backfill graded gravel in layers between the pile caps, and a small compacting machine is used for compaction.

[0014] Furthermore, in step S02, when the horizontal slope of the original ground is 1:5 to 1:2.5, the original ground surface is excavated by an excavator in combination with manual excavation. The excavator is first used to excavate the large surface of the step, and then the step is precisely trimmed manually. The step width is not less than 2.0m, and an inward slope of 2-4% is set. The coordinates of the location where the step needs to be excavated are calculated in advance by the surveyor based on the construction drawings, and excavation construction is carried out after on-site measurement and layout.

[0015] Gravel blind ditch: excavate a trapezoidal trench with a bottom width of not less than 0.8m, a depth of ≤1m, and a side slope ratio of 1:1 on the original ground. Then use an excavator and a loader to backfill the gravel into the trapezoidal trench in layers, and use a small compacting machine to compact it;

[0016] Intercepting drainage ditch: After the roadbed is cleared, an intercepting ditch is set up on the top of the road cutting slope to intercept the running water and rainwater on the slope to prevent it from flowing directly into the roadbed. An excavator is used to dig the drainage ditch along the longitudinal edge of the roadbed to drain the water within the roadbed into the existing ditch to prevent the water from soaking the roadbed. The intercepting drainage ditch adopts plain C20 concrete structure, and the wooden formwork is manufactured and installed on site. The concrete is poured manually with the help of machinery, and an expansion joint is set every 10-15m.

[0017] Furthermore, in step S02, the raw materials are selected as follows: graded sand and gravel coarse-grained soil is used as filler for roadbed filling, and soil samples are tested and inspected before filling construction. Soil samples that fail the test are strictly prohibited from being used as filler in construction;

[0018] Layered filling: The roadbed is filled in layers, with the compacted thickness of each layer not exceeding 30cm. It is leveled with a bulldozer and a grader, and compacted with a vibratory roller of not less than 18t. Fillers with different properties are filled in horizontal layers and sections and compacted in layers. The same type of filler is used for the same layer of roadbed and mixed filling is not allowed. The continuous thickness of the filling layer of each filler after compaction is not less than 500mm. Fillers with good water stability or low frost heave sensitivity are used on the upper part of the roadbed. Fillers with good water stability are used in sections with groundwater or submerged embankments.

[0019] Furthermore, in step S02, the geogrid is: three consecutive layers of geogrids with a tensile strength of ≥80 kN / m are set at the bottom of the roadbed, at the height of each level of the roadbed slope platform, and 20 cm below the top of the roadbed. Each layer of geogrid is 30 cm apart. When laying the geogrid, it is straightened and smooth, close to the underlying layer, without wrinkles. The longitudinal overlap length between the upper and lower layers is not less than 10 cm. High-strength plastic buckles are used to fasten it, with one buckle every 10 cm. Then, a U-shaped steel nail is set every 2 m in the overlapping direction, and the steel nail is pressed into the soil 25 cm;

[0020] General tamping reinforcement: When the roadbed fill height exceeds 15m, general tamping shall be used for reinforcement and compaction after layered rolling has achieved the specified compaction degree. The lowest layer of the first general tamping shall be at least 4m above the ground. When the original foundation is treated with cement mixing piles and CFG piles, the lowest layer shall be at least 6m above the ground, and the general tamping layer spacing shall be 6m. General tamping shall be carried out away from structures and shall not be carried out within 15m to the left and right of structures and 8m from the top of structures. Hydraulic tamping machinery shall be used for supplementary compaction. General tamping shall be carried out using a crawler crane and a tamping hammer. The tamping points shall be arranged in an equilateral triangle with a spacing of 1.5m, and the hammer marks shall overlap by 1 / 4 of the hammer diameter. General tamping shall be carried out using two passes of spot tamping and one pass of full tamping. The spot tamping shall be carried out in a skipping manner, with at least 6 strikes per point, and the tamping depth shall be less than 5cm. The general tamping construction sequence must be controlled in a sequential manner from the centerline of the roadbed to both sides, and shall not be carried out from the periphery to the center.

[0021] Furthermore, in step S03, the road subbase layer uses 20 cm thick graded crushed stone; the subbase layer is mixed in a centralized site, transported to the construction site by a transport vehicle, paved by an intelligent paver, and compacted by a combination of a vibratory roller and a rubber-tyred roller.

[0022] Furthermore, in the step S03, the upper base of the road surface adopts 25 cm thick 5% cement stabilized graded gravel, and the lower base adopts 25 cm thick 4% cement stabilized graded gravel, and cement slurry is set between the upper and lower bases; the base is mixed in a centralized site, transported to the construction site by a transport vehicle, paved by an intelligent paver, compacted by a combination of a vibratory roller and a tire-type rubber-wheel roller, and covered with geotextile for maintenance.

[0023] Furthermore, in the step S03, the pavement surface layer adopts 4cm fine-grained SBS modified asphalt mastic macadam concrete SMA-13C + 6cm SBS modified medium-grained asphalt concrete AC-20C + 6cm medium-grained asphalt concrete AC-20C, a modified emulsified asphalt tack coat is set between the surface layers, an emulsified asphalt penetration coat and a modified asphalt seal coat are set between the surface layer and the base layer, and a modified asphalt concrete surface layer is adopted; before the surface layer is constructed, the surface of the base layer is cleaned and sprayed with tack coat oil; the pavement surface layer mixture is mixed in a centralized site, transported to the construction site by a transport vehicle, paved by an intelligent paver, and compacted by a combination of a vibratory roller, a double-steel-wheel vibratory roller and a tire-type rubber-wheel roller.

[0024] Furthermore, intelligent dynamic monitoring and surveillance: During the construction process, monitoring piles are set up on the cutting slope 2m outside the intercepting drainage ditch, at the foot of the roadbed slope, on each slope platform, and on the top of the retaining wall. Settlement observation poles are set up on both shoulders and in the center of the road, with a group set up every 50m along the route. The intelligent monitoring system consists of an intelligent monitoring system and external monitoring points. A solar-powered intelligent monitoring information collector is set up at each observation point to cooperate with the intelligent monitoring system to monitor the roadbed settlement and displacement in real time. According to the monitoring results, a scientific adjustment basis is provided for the roadbed filling in real time to ensure that the roadbed filling is scientific and reasonable.

[0025] After the construction is completed and the roadbed is filled, the intelligent monitoring points and monitoring systems will continue to monitor and comprehensively evaluate the overall stability and safety of the roadbed and pavement in the mountainous settlement section. If there are any abnormalities, timely alarms will be issued to avoid safety accidents such as roadbed instability and landslides.

[0026] Beneficial effects of this application:

[0027] 1. This application adopts geological exploration and multiple reinforcement measures to comprehensively treat the settlement sections of mountain roads. From foundation treatment to roadbed filling and drainage to pavement structure optimization, each link cooperates and works synergistically with each other, which can effectively improve the stability and durability of the roadbed and pavement, and solve the problem of road settlement in mountainous areas.

[0028] 2. Through detailed investigation and evaluation of the settlement section, different settlement areas were divided and targeted reinforcement measures were taken, which improved the reinforcement effect while reducing the construction cost.

[0029] 3. Setting up intercepting and drainage facilities in front of the roadbed can timely remove the natural water in the roadbed, reduce the water soaking of the roadbed, and further improve the stability of the roadbed.

[0030] 4. The laying of geogrids on the roadbed and pavement base and the use of modified asphalt concrete surface layer have improved the overall performance of the roadbed and pavement, enhanced the pavement's anti-skid, durability and anti-deformation ability, and ensured driving safety and comfort.

[0031] 5. Intelligent settlement and displacement monitoring and maintenance during and after construction can detect problems in a timely manner and take measures to deal with them, ensuring the long-term stable operation of the roadbed and pavement.

[0032] The aforementioned main solution of this application and its further options can be freely combined to form multiple solutions, all of which are solutions that can be adopted and protected by this application; and in this application, (non-conflicting options) can also be freely combined with each other and with other options. After understanding the solution of this application, those skilled in the art will understand that there are many combinations based on existing technology and common knowledge, all of which are technical solutions to be protected by this application, and they are not exhaustive here. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a plan view of cement mixing pile construction for soft soil foundation treatment in this application.

[0034] Figure 2 This is a schematic elevation diagram of the cement mixing pile construction for soft soil foundation treatment in this application.

[0035] Figure 3 This is a plan view of the CFG pile construction for soft soil foundation treatment in this application.

[0036] Figure 4 This is a schematic elevation diagram of the CFG pile construction for soft soil foundation treatment in this application.

[0037] Figure 5 This is a schematic diagram of the step excavation for this application.

[0038] Figure 6 This is a schematic diagram of the stone facade of this application.

[0039] Figure 7 This is a schematic diagram of the plan layout of cement mixing piles and gravel blind ditches for soft soil foundation treatment in this application.

[0040] Figure 8 This is the layout diagram of the intercepting drainage ditch in this application Figure 1 .

[0041] Figure 9 This is the layout diagram of the intercepting drainage ditch in this application Figure 2 .

[0042] Figure 10 This is a schematic diagram of the geogrid arrangement and general tamping reinforcement construction layers for this application.

[0043] Figure 11 This is a plan view of the layout of monitoring points for this application.

[0044] Figure 12 This is a schematic elevation diagram of the layout of monitoring points for this application. DETAILED DESCRIPTION

[0045] The following non-limiting examples illustrate the present application.

[0046] Example 1

[0047] refer to Figures 1 to 12 As shown, a comprehensive reinforcement construction method for the roadbed and pavement of a mountain road settlement section includes the following steps: Step S01, geological exploration and analysis.

[0048] In step S01, geological radar, drilling, and measurement are used to survey the settlement section of the mountain road to obtain information on the geological structure, groundwater level, geological core samples, foundation bearing capacity, and settlement causes. The settlement degree and development trend of the settlement section are evaluated and divided into different settlement areas.

[0049] According to the geological and hydrological conditions of the roadbed in the mountainous settlement section, the original topography, the original foundation bearing capacity, and the roadbed filling height, different settlement areas are divided. After comprehensive analysis, the corresponding treatment method is selected to form a composite foundation.

[0050] Step S02, roadbed layered treatment and reinforcement: first perform roadbed foundation treatment, then perform roadbed filling: roadbed foundation treatment includes at least one treatment method of replacement filling, cement mixing piles, CFG piles, steps, gravel blind ditches and intercepting drainage ditches, and combined reinforcement is performed according to different situations.

[0051] Replacement filling: For shallow soft foundations with a depth of less than 3 meters, the replacement filling method is used to dig out the soft soil layer and replace it with graded crushed stone and gravel materials. An excavator is used in conjunction with a scraper to spread and level the materials in layers, and a vibratory roller of no less than 18t is used to compact the materials in layers. The compacted thickness of each layer shall not exceed 30cm, and the compaction degree shall not be less than 96%.

[0052] Cement mixing pile: reference Figure 1 and Figure 2 As shown, for deep, soft foundations with a depth greater than 3 meters and a fill height less than 15 meters, high-pressure rotary grouting is used. RTK (Real-Time Kinematic Carrier Phase Differential) is used to arrange piles at intervals of no more than 2 meters. High-pressure spraying pile drivers then drill holes into the foundation. Cement slurry is sprayed at high pressure, mixing with the soil to form a cement-soil reinforcement, improving the foundation's bearing capacity. After the cement-mixed piles pass inspection, a graded gravel cushion layer at least 50 cm thick is placed on top of the piles. This graded gravel cushion layer is then spread, leveled, and compacted in layers.

[0053] CFG pile (cement fly ash gravel pile): reference Figure 3 and Figure 4 As shown, for deep soft foundations with a depth greater than 3 meters and a fill height greater than 15 meters, the auger piling method is used. RTK is used to arrange pile positions at intervals no greater than 1.7 meters. High-pressure auger piling machinery is then used to drill holes in the foundation and pour the mixture into the foundation to form a complete pile body. After the pile body has passed inspection, a small excavator is used in conjunction with manual excavation to excavate the pile head. A level is used to measure and stake out the designed elevation of the pile head, and a cutter is used to remove the excess pile head.

[0054] A reinforced concrete pile cap is set at the top of each CFG pile. The pile cap formwork is made on-site using wooden formwork. The pile cap steel bars prefabricated in the steel bar yard are placed in the formwork. After acceptance, concrete pouring and maintenance work are carried out. A small excavator is used to backfill graded gravel in layers between the pile caps, and a small compacting machine is used for compaction.

[0055] Stairs: Reference Figure 5 As shown, when the original ground slope is 1:5 to 1:2.5, the original surface is excavated by excavators in conjunction with manual excavation of steps. The excavator is first used to excavate the large surface of the steps, and then the steps are precisely trimmed by manual labor. The step width is not less than 2.0m, and the slope is set inward at 2-4%. The coordinates of the locations where steps need to be excavated are calculated in advance by surveyors based on the construction drawings. Excavation construction is carried out after on-site measurement and layout.

[0056] Gravel blind ditch: reference Figure 6 and Figure 7 As shown, a trapezoidal trench with a bottom width of not less than 0.8m, a depth of ≤1m and a side slope ratio of 1:1 is excavated on the original ground. Then, an excavator and a loader are used to backfill the crushed stones into the trapezoidal trench in layers, and a small compacting machine is used for rolling and compacting.

[0057] Intercepting Drainage Gutter: Reference Figure 8 and Figure 9 As shown in the figure, after the roadbed is cleared, an intercepting ditch is installed at the top of the cutting slope to intercept runoff and rainwater on the slope, preventing it from flowing directly into the roadbed. An excavator is used to dig a drainage ditch along the longitudinal edge of the roadbed to drain water within the roadbed into the existing ditch, preventing it from being soaked. The intercepting ditch is constructed with plain C20 concrete. Wooden formwork is fabricated and installed on-site, with manual and mechanical concrete pouring. Expansion joints are provided every 10-15 meters.

[0058] Roadbed filling includes raw material selection, layered filling, geogrid and general tamping reinforcement.

[0059] Selection of raw materials: Graded sand, gravel and coarse-grained soil are used as fillers for roadbed filling, and soil samples are tested and inspected before filling construction. Soil samples that fail the test are strictly prohibited from being used as fillers in construction.

[0060] Layered Filling: The roadbed is filled in layers, with each layer compacted no thicker than 30cm. Leveling is performed using a bulldozer and a motor grader, and compacted using a vibratory roller weighing no less than 18 tons. Fillers of varying properties are layered and compacted in sections. The same filler type should be used in the same roadbed layer; mixing is prohibited. The continuous thickness of each filler layer after compaction should be no less than 500mm. Fillers with good water stability or low frost heave sensitivity should be used on the upper portion of the roadbed. For sections with groundwater or submerged embankments, water-stable fillers should be used.

[0061] Geogrids: Reference Figure 10 As shown, three consecutive layers of geogrids with a tensile strength of ≥80kN / m are set at the bottom of the roadbed, at the height of each level of the roadbed slope platform and 20cm below the top of the roadbed. Each layer of geogrid is 30cm apart. When laying the geogrid, it should be straightened and smooth, close to the underlying layer, without wrinkles. The longitudinal overlap length between the upper and lower layers should not be less than 10cm. It should be fastened with high-strength plastic buckles, with one buckle every 10cm. It is strictly forbidden to use wire binding. Afterwards, a U-shaped steel nail is set every 2m along the overlap direction, and the steel nail is pressed into the soil 25cm.

[0062] General reinforcement: reference Figure 10 As shown, when the roadbed fill height exceeds 15m, after layered rolling has achieved the required compaction degree, conventional tamping is used for reinforcement and compaction. The lowest layer of the initial conventional tamping must be at least 4m above the ground. When the existing foundation is treated with cement mixing piles and CFG piles, the lowest layer must be at least 6m above the ground, and the conventional tamping layer spacing must be 6m. Conventional tamping must be performed away from structures. Conventional tamping is prohibited within 15m to the left and right of structures and 8m from the top of the structure. Hydraulic tamping machinery should be used for supplementary compaction.

[0063] General tamping is performed using a crawler crane and tamping hammers. Tamping points are arranged in an equilateral triangle, spaced 1.5 meters apart, with the hammer marks overlapping by 1 / 4 of the hammer diameter (0.5 meters). General tamping involves two passes of spot tamping and one full tamping. Spot tamping is performed in a continuous flow, with no fewer than six strikes per point. A tamping depth of less than 5 cm is considered satisfactory. General tamping must be performed sequentially from the centerline of the roadbed toward both sides; it must not be performed from the periphery toward the center.

[0064] Step S03, pavement structure optimization construction: including optimization construction of subbase, base layer and surface layer.

[0065] Subbase: The pavement subbase utilizes 20cm thick graded crushed stone to enhance the overall stability and bearing capacity of the pavement structure. The subbase is mixed at a centralized site, transported to the construction site by truck, and spread using an intelligent paver. Compacted using a combination of vibratory and rubber-tyred rollers.

[0066] Base: The upper base layer utilizes a 25cm-thick, 5% cement-stabilized graded crushed stone, while the lower base layer utilizes a 25cm-thick, 4% cement-stabilized graded crushed stone. A cement slurry is applied between the upper and lower base layers to enhance the connection and integrity of the layers. The base layer is mixed at a centralized site, transported to the construction site by a transporter, and paved with an intelligent paver. It is compacted using a combination of a vibratory roller and a rubber-tyred roller, and then covered with a geotextile for maintenance.

[0067] Surface layer: The pavement surface layer utilizes 4cm fine-grained SBS modified mastic macadam asphalt concrete (SMA-13C), 6cm SBS modified medium-grained asphalt concrete (AC-20C), and 6cm medium-grained asphalt concrete (AC-20C). A modified emulsified asphalt tack coat is applied between the surface layers, and an emulsified asphalt penetration coat and modified asphalt seal coat are installed between the surface layer and the base layer. The modified asphalt concrete surface layer improves the pavement's skid resistance and durability. Before construction of the surface layer, the base layer surface is cleaned and sprayed with tack coat oil.

[0068] The pavement surface mixture is mixed in a centralized site, transported to the construction site by transport vehicles, spread by intelligent pavers, and compacted by a combination of vibratory rollers, double steel-wheel vibratory rollers, and tire-type rubber-wheel rollers.

[0069] During the construction process of step S02 and step S03 and after the construction is completed, intelligent dynamic monitoring is carried out.

[0070] Intelligent dynamic monitoring: reference Figure 11 and Figure 12 As shown, during the construction process, monitoring piles were set up on the cutting slope 2m outside the intercepting drainage ditch, at the foot of the roadbed slope, on each slope platform, and on the top of the retaining wall. Settlement observation poles were set up on the shoulders on both sides and in the center of the road, with one group set up every 50m along the route.

[0071] The intelligent monitoring and surveillance system consists of an intelligent monitoring system and external monitoring points. Each observation point is equipped with a solar-powered intelligent monitoring information collector, which works with the intelligent monitoring system to monitor the subgrade settlement and displacement in real time. Based on the monitoring results, a scientific adjustment basis is provided for the subgrade filling in real time to ensure that the subgrade filling is scientific and reasonable.

[0072] After the construction is completed, the roadbed filling and road surface optimization are completed, the intelligent monitoring points and monitoring systems will continue to monitor and comprehensively evaluate the overall stability and safety of the roadbed and road surface in the mountainous settlement section. If there are any abnormalities, timely alarms will be issued to avoid safety accidents such as roadbed instability and landslides.

[0073] The aforementioned basic examples and their further selected examples can be freely combined to form multiple embodiments, all of which are embodiments that can be adopted and claimed for protection in this application. In this application, each selected example can be arbitrarily combined with any other basic examples and selected examples.

[0074] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A comprehensive reinforcement construction method for roadbed and pavement in a mountainous road settlement section, characterized in that: The method comprises the following steps: Step S01, geological exploration and analysis; Step S02, roadbed layered treatment and reinforcement: first, roadbed foundation treatment is performed, followed by roadbed filling. Roadbed foundation treatment includes at least one of replacement filling, cement mixing piles, CFG piles, steps, gravel blind ditches, and intercepting drainage ditches. Roadbed filling includes raw material selection, layered filling, geogrid reinforcement, and general tamping reinforcement. Step S03, pavement structure optimization construction: includes optimized construction of the subbase, base, and surface layers. During the construction process of step S02 and step S03 and after the construction is completed, intelligent dynamic monitoring is carried out.

2. The comprehensive reinforcement construction method for roadbed and pavement in a mountainous road settlement section according to claim 1 is characterized by: In step S01, the settlement section of the mountain road is surveyed by means of geological radar, drilling, and measurement to obtain information on the geological structure, groundwater level, geological core samples, foundation bearing capacity, and settlement causes, and the settlement degree and development trend of the settlement section are evaluated, and different settlement areas are divided; the different settlement areas are divided according to the geological and hydrological conditions of the mountain road subsidence section, the original topography, the original foundation bearing capacity, and the roadbed filling height, and the corresponding treatment method is selected after comprehensive analysis to form a composite foundation.

3. The comprehensive reinforcement construction method for roadbed and pavement in a mountainous road settlement section according to claim 1 is characterized by: In step S02, the backfill method is used to excavate the soft soil layer and replace it with graded crushed stone and gravel materials for shallow soft foundation with a depth of less than 3 meters. The backfill method is used to spread and level the soft soil layer in layers using an excavator and a scraper. The soft soil layer is then compacted in layers using a vibratory roller of not less than 18 tons. The thickness of each layer does not exceed 30 cm, and the degree of compaction is not less than 96%. Cement mixing piles: For deep soft foundations with a depth greater than 3 meters and a fill height less than 15 meters, high-pressure rotary jet grouting is used. RTK is used to arrange pile positions at intervals of no more than 2 meters. High-pressure spray pile driving machinery is then used to drill holes in the foundation. Cement slurry is sprayed at high pressure and mixed with the soil to form a cement-soil reinforcement. After the cement mixing piles have passed inspection, a graded gravel cushion layer at least 50 cm thick is placed on top of the piles. The graded gravel cushion layer is then spread, leveled, rolled, and compacted in layers. CFG piles: For deep soft foundations with a soft foundation depth greater than 3 meters and a fill height greater than 15m, the spiral drilling method is adopted, and the pile positions are arranged at intervals of no more than 1.7m using RTK. Then, a high-pressure spiral pile driving machine is used to drill holes in the foundation and pour the mixture to form a complete pile body. After the pile body is accepted, a small excavator is used in combination with manual labor to dig out the pile head, a level is used to measure and lay out the designed elevation position line of the pile head, and a cutting machine is used to cut off the excess pile head; each CFG pile is provided with a reinforced concrete pile cap at the top of the pile, and the pile cap formwork is made on-site using a wooden formwork. The pile cap steel bars prefabricated in the steel bar yard are placed in the formwork. After acceptance, concrete pouring and maintenance work are carried out. A small excavator is used to backfill graded gravel in layers between the pile caps, and a small compacting machine is used for compaction.

4. The comprehensive reinforcement construction method for roadbed and pavement in a mountainous road settlement section according to claim 1 or 3 is characterized in that: In step S02, steps: when the original ground slope is 1:5 to 1:2.5, steps are excavated on the original ground surface using an excavator in combination with manual labor. The excavator is first used to excavate and shape the large surface of the steps, and then the steps are precisely trimmed manually. The step width is not less than 2.0m, and an inward slope of 2 to 4% is set. The coordinates of the parts where the steps need to be excavated are calculated in advance by the surveyors according to the construction drawings, and excavation construction is carried out after on-site measurement and layout. Gravel blind ditch: excavate a trapezoidal trench with a bottom width of not less than 0.8m, a depth of ≤1m, and a side slope ratio of 1:1 on the original ground. Then use an excavator and a loader to backfill the gravel into the trapezoidal trench in layers, and use a small compacting machine to compact it; Intercepting drainage ditch: After the roadbed is cleared, an intercepting ditch is set up on the top of the road cutting slope to intercept the running water and rainwater on the slope to prevent it from flowing directly into the roadbed. An excavator is used to dig the drainage ditch along the longitudinal edge of the roadbed to drain the water within the roadbed into the existing ditch to prevent the water from soaking the roadbed. The intercepting drainage ditch adopts plain C20 concrete structure, and the wooden formwork is manufactured and installed on site. The concrete is poured manually with the help of machinery, and an expansion joint is set every 10-15m.

5. The comprehensive reinforcement construction method for roadbed and pavement in a mountainous road settlement section according to claim 1 is characterized by: In step S02, raw materials are selected: graded sand and gravel coarse-grained soil is used as filler for roadbed filling, and soil samples are tested before filling construction. Soil samples that fail the test are strictly prohibited from being used as filler in construction; Layered filling: The roadbed is filled in layers, with the compacted thickness of each layer not exceeding 30cm. It is leveled with a bulldozer and a grader, and compacted with a vibratory roller of not less than 18t. Fillers with different properties are filled in horizontal layers and sections and compacted in layers. The same type of filler is used for the same layer of roadbed and mixed filling is not allowed. The continuous thickness of the filling layer of each filler after compaction is not less than 500mm. Fillers with good water stability or low frost heave sensitivity are used on the upper part of the roadbed. Fillers with good water stability are used in sections with groundwater or submerged embankments.

6. The comprehensive reinforcement construction method for roadbed and pavement in a mountainous road settlement section according to claim 1 or 5, characterized in that: In the step S02, the geogrid is: 3 consecutive layers of geogrids with a tensile strength of ≥80 kN / m are set at the bottom of the roadbed, at the height of each level of the roadbed slope platform, and 20 cm below the top of the roadbed. Each layer of geogrid is 30 cm apart. When laying the geogrid, it is straightened and smooth, close to the underlying layer, without wrinkles. The longitudinal overlap length between the upper and lower layers is not less than 10 cm. High-strength plastic buckles are used to fasten it, with one buckle every 10 cm. Then, a U-shaped steel nail is set every 2 m in the overlapping direction, and the steel nail is pressed into the soil 25 cm; General tamping reinforcement: When the roadbed fill height exceeds 15m, general tamping shall be used for reinforcement and compaction after layered rolling has achieved the specified compaction degree. The lowest layer of the first general tamping shall be at least 4m above the ground. When the original foundation is treated with cement mixing piles and CFG piles, the lowest layer shall be at least 6m above the ground, and the general tamping layer spacing shall be 6m. General tamping shall be carried out away from structures and shall not be carried out within 15m to the left and right of structures and 8m from the top of structures. Hydraulic tamping machinery shall be used for supplementary compaction. General tamping shall be carried out using a crawler crane and a tamping hammer. The tamping points shall be arranged in an equilateral triangle with a spacing of 1.5m, and the hammer marks shall overlap by 1 / 4 of the hammer diameter. General tamping shall be carried out using two passes of spot tamping and one pass of full tamping. The spot tamping shall be carried out in a skipping manner, with at least 6 strikes per point, and the tamping depth shall be less than 5cm. The general tamping construction sequence must be controlled in a sequential manner from the centerline of the roadbed to both sides, and shall not be carried out from the periphery to the center.

7. The comprehensive reinforcement construction method for roadbed and pavement in a mountainous road settlement section according to claim 1 is characterized by: In step S03, the road subbase layer is made of 20 cm thick graded crushed stone; the subbase layer is mixed in a centralized site, transported to the construction site by a transport vehicle, paved by an intelligent paver, and compacted by a combination of a vibratory roller and a rubber-tyred roller.

8. The comprehensive reinforcement construction method for roadbed and pavement in a mountainous road settlement section according to claim 1 is characterized by: In step S03, the upper base of the road surface uses 25 cm thick 5% cement stabilized graded gravel, and the lower base uses 25 cm thick 4% cement stabilized graded gravel, and cement slurry is set between the upper and lower bases; the base is mixed in a centralized site, transported to the construction site by a transport vehicle, paved by an intelligent paver, compacted by a combination of a vibratory roller and a tire-type rubber-wheel roller, and covered with geotextile for maintenance.

9. The comprehensive reinforcement construction method for roadbed and pavement in a mountainous road settlement section according to claim 1, 7 or 8, characterized in that: In step S03, the pavement surface layer adopts 4cm fine-grained SBS modified asphalt mastic macadam concrete SMA-13C + 6cm SBS modified medium-grained asphalt concrete AC-20C + 6cm medium-grained asphalt concrete AC-20C, a modified emulsified asphalt tack coat is set between the surface layers, an emulsified asphalt penetration coat and a modified asphalt seal coat are set between the surface layer and the base layer, and a modified asphalt concrete surface layer is adopted; before the surface layer is constructed, the surface of the base layer is cleaned and sprayed with tack coat oil; the pavement surface layer mixture is mixed in a centralized site, transported to the construction site by a transport vehicle, paved by an intelligent paver, and compacted by a combination of a vibratory roller, a double-steel-wheel vibratory roller, and a tire-type rubber-wheel roller.

10. The comprehensive reinforcement construction method for roadbed and pavement in a mountainous road settlement section according to claim 1 is characterized by: Intelligent dynamic monitoring: During construction, monitoring piles are installed on the cutting slope 2m outside the intercepting drainage ditch, at the foot of the roadbed slope, on each slope platform, and on the top of the retaining wall. Settlement observation poles are set on both shoulders and in the center of the road, with a group set every 50m along the route. The intelligent monitoring system consists of an intelligent monitoring system and external monitoring points. A solar-powered intelligent monitoring information collector is installed at each observation point to cooperate with the intelligent monitoring system to monitor the roadbed settlement and displacement in real time. The monitoring results provide a scientific basis for real-time adjustment of the roadbed filling to ensure that the roadbed filling is scientific and reasonable. After the construction is completed and the roadbed is filled, the intelligent monitoring points and monitoring systems will continue to monitor and comprehensively evaluate the overall stability and safety of the roadbed and pavement in the mountainous settlement section. If there are any abnormalities, timely alarms will be issued to avoid safety accidents such as roadbed instability and landslides.

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