High-water-level roadbed treatment structure and construction process thereof

Abstract

The invention relates to the technical field of roadbed treatment structures. The invention discloses a high-water-level roadbed treatment structure and a construction process thereof. The high-water-level roadbed treatment structure comprises a composite drainage layer, an anti-seepage water-resisting layer, a composite reinforcing layer and a protective layer. The construction technology comprises the following steps that obstacles such as weeds, trees and stones in a construction area are cleaned, the ground is leveled, and drainage grooves are dug in the two sides of a roadbed; a sand well is driven into the soft soil layer to serve as a vertical drainage body; a gravel layer is laid, mechanical compaction is conducted, a gravel layer is laid, mechanical compaction is conducted, and a composite drainage layer is formed; an HDPE geomembrane is laid on the composite drainage layer, a seam is welded, and an anti-seepage water-resisting layer is formed; a geogrid is laid above the anti-seepage water-resisting layer; the prestressed pipe piles are driven to form a composite reinforcing layer; and precast concrete is laid on the composite reinforcing layer to form a protective layer. The high-water-level subgrade treatment structure can effectively inhibit subgrade settlement and improve subgrade stability.

Description

Technical Field

[0001] The present application relates to the technical field of roadbed treatment structures, and in particular to a high-water-level roadbed treatment structure and a construction process thereof. Background Art

[0002] With the rapid development of my country's economy, the transportation network is also constantly improving, especially the construction of the national expressway network is advancing by leaps and bounds. As the "Vertical Four" in the "71118" plan of the national expressway network, the G35 Jinan-Guangzhou Expressway shoulders the important task of connecting North China and South China. The average traffic volume from Yinjialin Hub to Dongping Lake Hub has reached 62,480 pcu / d, and the average traffic volume from Dongping Lake Hub to Wangguantun Hub has reached 41,810 pcu / d, of which large vehicles account for 26.6%. Faced with such great traffic pressure, the existing road service level can no longer meet the growing transportation demand, and it is urgently necessary to carry out reconstruction and expansion projects to improve road capacity and service level.

[0003] During the renovation and expansion process, the project area faced many challenges brought by natural conditions. On the one hand, there are many ponds distributed in the area, and a large amount of silt is deposited at the bottom of the ponds, which has an adverse impact on the project and may also cause problems such as uneven settlement of the roadbed. On the other hand, during the flood season every year, due to the large amount of floods and dense surface runoff, many sections of the roadbed are in a high water level state. In this case, the roadbed soil is easily softened by water immersion, resulting in reduced strength, increasing the difficulty of construction, and easily causing uneven settlement of the roadbed, overall sinking, slope instability and other diseases, which directly threaten the safety of the roadbed project.

[0004] The current treatment methods for high-water-level roadbeds mainly include traditional drainage consolidation, replacement and filling, and compaction pile methods. However, these traditional methods often fail to achieve ideal results under complex geological conditions. For example, although the drainage consolidation method can effectively lower the groundwater level, when implemented in soft soil areas, the soil has a large compressibility, the settlement process is long and difficult to control, and it is difficult to meet the needs of rapid construction; the replacement and filling method requires a large amount of filler, which is not only costly, but also has a long construction period; the compaction pile method is limited by geological conditions and has limited effect on improving soft soil layers.

[0005] Therefore, it is urgent to develop a high-water level roadbed treatment structure that can effectively inhibit roadbed settlement and improve roadbed stability. Summary of the invention

[0006] In order to solve at least one of the above technical problems, a high-water level roadbed treatment structure is developed that can effectively suppress roadbed settlement and improve roadbed stability. The present application provides a high-water level roadbed treatment structure and a construction process thereof.

[0007] On the one hand, the present application provides a high-water level roadbed treatment structure, comprising a composite drainage layer, an anti-seepage waterproof layer, a composite reinforcement layer and a protective layer; The composite drainage layer includes a vertical drainage body and a horizontal drainage layer, and the horizontal drainage layer is crushed stone and sand; The anti-seepage waterproof layer is a HDPE geomembrane, and the raw material composition of the HDPE geomembrane includes, by weight: 90-110 parts of high-density polyethylene, 10-20 parts of chlorinated polyethylene, 2-8 parts of carbon black, 1-2 parts of polyacrylic acid intercalated hydrotalcite, 1-2 parts of antioxidant, 0.5-1 part of anti-aging agent and 0.5-1 part of stabilizer; The composite reinforcement layer includes geogrids and prestressed pipe piles; The protective layer is precast concrete.

[0008] By adopting the above technical scheme, the high-water level roadbed treatment structure of the present application can effectively suppress the settlement of the roadbed and improve the stability of the roadbed through multi-level treatment measures. The present application forms a systematic protection system through composite drainage, anti-seepage and water-proofing, composite reinforcement and protection, thereby improving the overall stability and durability of the roadbed. The composite drainage layer can accelerate the discharge of water inside the roadbed, reduce the impact of water on the roadbed, and prevent the soft soil roadbed from settling due to water accumulation. The anti-seepage and water-proof layer can prevent the rising groundwater from eroding the roadbed and maintain the dry state inside the roadbed. The composite reinforcement layer can enhance the overall stability and bearing capacity of the roadbed and prevent uneven settlement of the roadbed under high water level conditions. Among them, by laying geogrids, the stability of the soil inside the roadbed is enhanced and its shear resistance is improved. By driving prestressed pipe piles, the vertical bearing capacity of the roadbed is enhanced to prevent the settlement of the soft soil foundation. The protective layer of the present application can protect the lower structure from the influence of the external environment, and at the same time provide a solid surface to prevent rainwater from directly eroding the roadbed.

[0009] Through the above-mentioned multi-level design, the high-water level roadbed treatment structure of the present application can effectively suppress the roadbed settlement, improve the stability of the roadbed, extend the service life of the roadbed, and ensure the safe operation of the road.

[0010] Optionally, in the composite drainage layer, the vertical drainage body is a sand well.

[0011] By adopting the above technical solutions, sand wells can improve drainage efficiency, effectively reduce the pore water pressure inside the roadbed, reduce the settlement of soft soil foundation, and improve the overall stability of the roadbed. It also helps to consolidate the soil and enhance the bearing capacity of the soil. In addition, sand wells are easy to construct and highly flexible.

[0012] Optionally, in the composite drainage layer, the average particle size of crushed stone is 20 to 40 mm, and the average particle size of sand and gravel is 5 to 20 mm.

[0013] By adopting the above technical solution, the particle size of the gravel and sand in the present application can achieve more effective drainage and ensure the stability and durability of the roadbed.

[0014] Optionally, in the HDPE geomembrane, the antioxidant is selected from at least one of antioxidant BHT, antioxidant 1010 and antioxidant DLTP.

[0015] By adopting the above technical solution, the antioxidant of the present application can improve the antioxidant performance of the HDPE geomembrane, thereby enhancing its durability and service life, thereby improving the stability and durability of the entire high water level roadbed treatment structure.

[0016] Optionally, in the HDPE geomembrane, the anti-aging agent is selected from at least one of antioxidant 264, antioxidant D and antioxidant IPPD.

[0017] By adopting the above technical solution, the anti-aging agent of the present application can improve the weather resistance and UV resistance of the HDPE geomembrane, thereby enhancing its stability and lifespan in long-term use.

[0018] Optionally, in the HDPE geomembrane, the stabilizer is selected from at least one of tribasic lead sulfate, dibasic lead phosphite and dibasic lead stearate.

[0019] By adopting the above technical solution, the stabilizer of the present application can improve the processing stability and long-term durability of the HDPE geomembrane.

[0020] Optionally, the preparation method of the HDPE geomembrane is: Step 1: mixing the high-density polyethylene and chlorinated polyethylene to prepare a premix; Step 2: adding the carbon black, polyacrylic acid intercalated hydrotalcite, antioxidant, anti-aging agent and stabilizer to the premix, mixing to obtain a mixture; Step 3: Extruding the mixture through an extruder and blowing a film to obtain the HDPE geomembrane.

[0021] By adopting the above technical solution, the preparation method of HDPE geomembrane of the present application can not only ensure the uniformity and stability of the material, but also optimize the comprehensive performance of the material, so that the prepared HDPE geomembrane has better durability, stability and applicability, and is suitable for the anti-seepage waterproof layer in the high water level roadbed treatment structure.

[0022] In a second aspect, the present application provides a construction process for the above-mentioned high water level roadbed treatment structure, comprising the following steps: S1. Clear weeds, trees, stones and other obstacles in the construction area, level the ground, and dig drainage ditches on both sides of the roadbed; S2. Sand wells are driven into the soft soil layer as vertical drainage bodies. The spacing between the sand wells is 1.5 to 2.5 meters and the insertion depth is 5 to 10 meters. S3, laying a gravel layer, compacting it mechanically, laying a sand and gravel layer, compacting it mechanically, and forming a composite drainage layer; S4. Lay HDPE geomembrane on the composite drainage layer and weld the seams to form an anti-seepage waterproof layer; S5. Lay geogrids on the anti-seepage waterproof layer in 2 to 3 layers, with the overlap length of geogrids being 30 to 50 cm; S6. Drive prestressed pipe piles at a spacing of 1.5 to 3 m to form a composite reinforcement layer; S7. Lay precast concrete on top of the composite reinforcement layer to form a protective layer.

[0023] By adopting the above technical scheme, the high-water level roadbed treatment structure construction process of the present application forms a systematic protection system from drainage, anti-seepage, reinforcement to protection, which can comprehensively improve the stability and durability of the roadbed.

[0024] Step S2 can accelerate the drainage of water in the soft soil layer and reduce the settlement of the roadbed; Step S3 can further improve the drainage capacity of the roadbed, reduce the impact of water on the roadbed, and enhance the stability of the roadbed; Step S4 can effectively isolate water and improve the durability of the roadbed; Step S5 can enhance the shear resistance and overall stability of the roadbed, effectively prevent the lateral slip of the roadbed soil, and improve the bearing capacity of the roadbed; Step S6 can enhance the vertical bearing capacity of the roadbed and prevent uneven settlement of the soft soil layer; Step S7 can prevent the external environment from eroding the roadbed.

[0025] Optionally, in step S3, the thickness of the gravel layer is 20 to 30 cm, and the thickness of the sand and gravel layer is 10 to 20 cm.

[0026] By adopting the above technical solution, the thickness of the gravel layer of the present application can provide greater porosity, thereby improving water permeability, ensuring that water can quickly pass through the gravel layer, reducing water accumulation inside the roadbed, and providing sufficient support to enhance the overall stability of the roadbed and prevent roadbed settlement caused by excessive moisture. The thickness of the sand and gravel layer of the present application has good filtering performance, can prevent fine particles from entering the gravel layer, avoid blockage of the gravel layer, and ensure long-term drainage effect. And further refine the drainage path, supplement the drainage function of the gravel layer, and improve the overall drainage efficiency.

[0027] Optionally, in step S7, the thickness of the precast concrete is 10 to 20 cm.

[0028] By adopting the above technical solution, the thickness of the precast concrete in the present application can enhance the overall stability of the roadbed and prevent uneven settlement of the soft soil layer.

[0029] In summary, the present invention includes at least one of the following beneficial technical effects: 1. The high-water level roadbed treatment structure of the present application can effectively suppress roadbed settlement and improve roadbed stability through multi-level treatment measures.

[0030] 2. The composite drainage layer of the present application can accelerate the discharge of water from the roadbed, reduce the impact of water on the roadbed, and prevent the soft soil roadbed from settling due to water accumulation.

[0031] 3. The high-water level roadbed treatment structure construction process of this application forms a systematic protection system from drainage, anti-seepage, reinforcement to protection, which can improve the stability and durability of the roadbed in all aspects. DETAILED DESCRIPTION

[0032] The present application is further described in detail below with reference to the embodiments.

[0033] This application designs a high water level roadbed treatment structure, including a composite drainage layer, an anti-seepage waterproof layer, a composite reinforcement layer and a protective layer; The composite drainage layer includes a vertical drainage body and a horizontal drainage layer, and the horizontal drainage layer is crushed stone and sand; The anti-seepage waterproof layer is a HDPE geomembrane, and the raw material composition of the HDPE geomembrane includes, by weight: 90-110 parts of high-density polyethylene, 10-20 parts of chlorinated polyethylene, 2-8 parts of carbon black, 1-2 parts of polyacrylic acid intercalated hydrotalcite, 1-2 parts of antioxidant, 0.5-1 part of anti-aging agent and 0.5-1 part of stabilizer; The composite reinforcement layer includes geogrids and prestressed pipe piles; The protective layer is precast concrete.

[0034] The construction process of the high water level roadbed treatment structure of the present application comprises the following steps: S1. Clear weeds, trees, stones and other obstacles in the construction area, level the ground, and dig drainage ditches on both sides of the roadbed; S2. Sand wells are driven into the soft soil layer as vertical drainage bodies. The spacing between the sand wells is 1.5 to 2.5 meters and the insertion depth is 5 to 10 meters. S3, laying a gravel layer, compacting it mechanically, laying a sand and gravel layer, compacting it mechanically, and forming a composite drainage layer; S4. Lay HDPE geomembrane on the composite drainage layer and weld the seams to form an anti-seepage waterproof layer; S5. Lay geogrids on the anti-seepage and waterproof layer in 2 to 3 layers, with the overlap length of geogrids being 30 to 50 cm; S6. Drive prestressed pipe piles at a spacing of 1.5 to 3 m to form a composite reinforcement layer; S7. Lay precast concrete on top of the composite reinforcement layer to form a protective layer.

[0035] The applicant has designed the technical solution of the present application to address the problem that the existing roadbed structure is difficult to achieve ideal roadbed stability under complex geological conditions and the roadbed settlement is serious.

[0036] The raw materials used in this application are as follows: High-density polyethylene: Dongguan Nabaichuan Plastic Chemical Co., Ltd., brand: F00952.

[0037] Chlorinated polyethylene: CAS: 63231-66-3.

[0038] Carbon black: Laiwu Tianlu Carbon Black Co., Ltd., carbon black N330.

[0039] Antioxidant 1010: CAS: 6683-19-8.

[0040] Antioxidant 264: CAS: 128-37-0.

[0041] Tribasic lead sulfate: CAS: 12202-17-4.

[0042] Mg(NO3)2·6H2O (magnesium nitrate hexahydrate): CAS: 13446-18-9.

[0043] Al(NO3)3·9H2O (aluminum nitrate nonahydrate): CAS: 7784-27-2.

[0044] Polyacrylic acid: CAS: 9003-01-4.

[0045] Potassium persulfate: CAS: 7727-21-1. Specific embodiments

[0046] The preparation method of the polyacrylic acid intercalated hydrotalcite used in Examples 1 to 3 is: Mix Mg(NO3)2·6H2O and Al(NO3)3·9H2O, add water to dissolve, and prepare a mixed salt solution; Mg 2+ and Al 3+ The molar ratio is 3:1; a sodium hydroxide solution with a mass fraction of 5% is added dropwise to the mixed salt solution, stirred to generate a precipitate, separated, washed, and dried to obtain a basic hydrotalcite; the basic hydrotalcite is ultrasonically dispersed in water to obtain a hydrotalcite suspension; polyacrylic acid is added to the hydrotalcite suspension, potassium persulfate is added, stirred at 70°C for 7h, separated, washed, and dried to obtain a polyacrylic acid intercalated hydrotalcite.

[0047] Examples 1 to 3 Example 1 This embodiment provides a high water level roadbed treatment structure, including a composite drainage layer, an anti-seepage waterproof layer, a composite reinforcement layer and a protective layer; The composite drainage layer includes a vertical drainage body and a horizontal drainage layer. The vertical drainage body is a sand well, and the horizontal drainage layer is crushed stone and sand and gravel. The average particle size of the crushed stone is 30mm, and the average particle size of the sand and gravel is 12mm. The anti-seepage waterproof layer is a HDPE geomembrane, and its raw material composition includes, by weight: 110 parts of high-density polyethylene, 10 parts of chlorinated polyethylene, 2 parts of carbon black, 2 parts of polyacrylic acid intercalated hydrotalcite, 1 part of antioxidant, 0.5 parts of anti-aging agent and 1 part of stabilizer; Among them, the antioxidant is antioxidant 1010; the anti-aging agent is antioxidant 264; the stabilizer is tribasic lead sulfate; The preparation method of HDPE geomembrane is: Step 1: mixing high-density polyethylene and chlorinated polyethylene to prepare a premix; Step 2: adding carbon black, polyacrylic acid intercalated hydrotalcite, antioxidant, anti-aging agent and stabilizer to the premix, mixing to obtain a mixture; Step 3: Extruding the mixed material through an extruder and blowing a film to obtain the HDPE geomembrane.

[0048] The composite reinforcement layer includes geogrid and prestressed pipe piles; the protective layer is precast concrete.

[0049] The construction process includes the following steps: S1. Clear weeds, trees, stones and other obstacles in the construction area, level the ground, and dig drainage ditches on both sides of the roadbed, with the drainage ditches 1.5m below the original roadbed surface; S2. Sand wells are driven into the soft soil layer as vertical drainage bodies. The spacing between the sand wells is 1.5m and the insertion depth is 5m. S3, laying a gravel layer with a thickness of 25 cm, mechanically compacting, laying a sand and gravel layer with a thickness of 15 cm, mechanically compacting, to form a composite drainage layer; S4. Lay HDPE geomembrane on the composite drainage layer and weld the seams to form an anti-seepage waterproof layer; S5. Lay geogrids on the anti-seepage waterproof layer in two layers, with an overlap length of 50 cm; S6. Drive prestressed pipe piles at a spacing of 1.5m to form a composite reinforcement layer; S7. Precast concrete is laid on top of the composite reinforcement layer. The thickness of the precast concrete is 15 cm to form a protective layer.

[0050] Example 2 This embodiment provides a high water level roadbed treatment structure, including a composite drainage layer, an anti-seepage waterproof layer, a composite reinforcement layer and a protective layer; The composite drainage layer includes a vertical drainage body and a horizontal drainage layer. The vertical drainage body is a sand well, and the horizontal drainage layer is crushed stone and sand and gravel. The average particle size of the crushed stone is 30mm, and the average particle size of the sand and gravel is 12mm. The anti-seepage waterproof layer is a HDPE geomembrane, and its raw material composition includes, by weight: 100 parts of high-density polyethylene, 15 parts of chlorinated polyethylene, 5 parts of carbon black, 1.5 parts of polyacrylic acid intercalated hydrotalcite, 1.5 parts of antioxidant, 0.75 parts of anti-aging agent and 0.75 parts of stabilizer; Among them, the antioxidant is antioxidant 1010; the anti-aging agent is antioxidant 264; the stabilizer is tribasic lead sulfate; The preparation method of HDPE geomembrane is: Step 1: mixing high-density polyethylene and chlorinated polyethylene to prepare a premix; Step 2: adding carbon black, polyacrylic acid intercalated hydrotalcite, antioxidant, anti-aging agent and stabilizer to the premix, mixing to obtain a mixture; Step 3: Extruding the mixture through an extruder and blowing a film to obtain the HDPE geomembrane.

[0051] The composite reinforcement layer includes geogrid and prestressed pipe piles; the protective layer is precast concrete.

[0052] The construction process includes the following steps: S1. Clear weeds, trees, stones and other obstacles in the construction area, level the ground, and dig drainage ditches on both sides of the roadbed, with the drainage ditches 1.5m below the original roadbed surface; S2. Sand wells are driven into the soft soil layer as vertical drainage bodies. The spacing between the sand wells is 2m and the insertion depth is 7.5m. S3, laying a gravel layer with a thickness of 25 cm, mechanically compacting, laying a sand and gravel layer with a thickness of 15 cm, mechanically compacting, to form a composite drainage layer; S4. Lay HDPE geomembrane on the composite drainage layer and weld the seams to form an anti-seepage waterproof layer; S5. Lay geogrids on the anti-seepage waterproof layer in three layers, with an overlap length of 40 cm; S6, driving prestressed pipe piles at a spacing of 2.2m to form a composite reinforcement layer; S7. Precast concrete is laid on the composite reinforcement layer. The thickness of the precast concrete is 15 cm to form a protective layer.

[0053] Example 3 This embodiment provides a high water level roadbed treatment structure, including a composite drainage layer, an anti-seepage waterproof layer, a composite reinforcement layer and a protective layer; The composite drainage layer includes a vertical drainage body and a horizontal drainage layer. The vertical drainage body is a sand well, and the horizontal drainage layer is crushed stone and sand and gravel. The average particle size of the crushed stone is 30mm, and the average particle size of the sand and gravel is 12mm. The anti-seepage waterproof layer is a HDPE geomembrane, and its raw material composition includes, by weight: 90 parts of high-density polyethylene, 20 parts of chlorinated polyethylene, 8 parts of carbon black, 1 part of polyacrylic acid intercalated hydrotalcite, 2 parts of antioxidant, 1 part of anti-aging agent and 0.5 parts of stabilizer; Among them, the antioxidant is antioxidant 1010; the anti-aging agent is antioxidant 264; the stabilizer is tribasic lead sulfate; The preparation method of HDPE geomembrane is: Step 1: mixing high-density polyethylene and chlorinated polyethylene to prepare a premix; Step 2: adding carbon black, polyacrylic acid intercalated hydrotalcite, antioxidant, anti-aging agent and stabilizer to the premix, mixing to obtain a mixture; Step 3: Extruding the mixed material through an extruder and blowing a film to obtain the HDPE geomembrane.

[0054] The composite reinforcement layer includes geogrid and prestressed pipe piles; the protective layer is precast concrete.

[0055] The construction process includes the following steps: S1. Clear weeds, trees, stones and other obstacles in the construction area, level the ground, and dig drainage ditches on both sides of the roadbed, with the drainage ditches 1.5m below the original roadbed surface; S2. Sand wells are driven into the soft soil layer as vertical drainage bodies. The spacing between the sand wells is 2.5m and the insertion depth is 10m. S3, laying a gravel layer with a thickness of 25 cm, mechanically compacting, laying a sand and gravel layer with a thickness of 15 cm, mechanically compacting, to form a composite drainage layer; S4. Lay HDPE geomembrane on the composite drainage layer and weld the seams to form an anti-seepage waterproof layer; S5. Lay geogrids on top of the anti-seepage waterproof layer in three layers, with an overlap length of 30 cm. S6. Drive prestressed pipe piles at a spacing of 3m to form a composite reinforcement layer; S7. Precast concrete is laid on top of the composite reinforcement layer. The thickness of the precast concrete is 15 cm to form a protective layer.

[0056] Comparative Examples 1 to 4 Comparative Example 1 The difference between Comparative Example 1 and Example 2 is that the composite drainage layer of Comparative Example 1 has no vertical drainage sand well, and the specific construction process is: S1. Clear weeds, trees, stones and other obstacles in the construction area, level the ground, and dig drainage ditches on both sides of the roadbed, with the drainage ditches 1.5m below the original roadbed surface; S2. Lay a gravel layer with a thickness of 25 cm and compact it mechanically, then lay a sand and gravel layer with a thickness of 15 cm and compact it mechanically to form a drainage layer; S3. Lay HDPE geomembrane on top of the drainage layer and weld the seams to form an anti-seepage waterproof layer; S4. Lay geogrids on the anti-seepage waterproof layer in three layers, with an overlap length of 40 cm; S5, driving prestressed pipe piles at a spacing of 2.2m to form a composite reinforcement layer; S6. Precast concrete is laid on top of the composite reinforcement layer. The thickness of the precast concrete is 15 cm to form a protective layer.

[0057] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that the anti-seepage waterproof layer of Comparative Example 2 is a commercially available HDPE geomembrane purchased from Chongqing Roadbed Geotechnical Building Materials Co., Ltd.

[0058] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that, in the HDPE geomembrane of the anti-seepage and waterproof layer of Comparative Example 3, no polyacrylic acid intercalated hydrotalcite is added.

[0059] Comparative Example 4 The difference between Comparative Example 4 and Example 2 is that the composite reinforcement layer of Comparative Example 4 has no prestressed pipe piles, and the specific construction process is as follows: S1, clearing obstacles such as weeds, trees, stones, etc. in the construction area, leveling the ground, and digging drainage grooves on both sides of the roadbed, and the drainage grooves are 1.5m lower than the original roadbed surface; S2. Sand wells are driven into the soft soil layer as vertical drainage bodies. The spacing between the sand wells is 2m and the insertion depth is 7.5m. S3, laying a gravel layer with a thickness of 25 cm, mechanically compacting, laying a sand and gravel layer with a thickness of 15 cm, mechanically compacting, to form a composite drainage layer; S4. Lay HDPE geomembrane on the composite drainage layer and weld the seams to form an anti-seepage waterproof layer; S5. Lay geogrids on the anti-seepage waterproof layer in three layers, with the overlap length of the geogrids being 40 cm to form a reinforcement layer; S6. Precast concrete is laid on top of the reinforcement layer. The thickness of the precast concrete is 15 cm to form a protective layer.

[0060] Experimental testing Test items and test methods 1. Roadbed settlement: Detect the post-construction settlement of the roadbed. The test method is as follows: The pile body is a Φ20mm stainless steel rod, the top is rounded and engraved with a cross line, and the bottom is welded with a hook. After the surface construction of the subgrade is completed (after the subgrade bottom construction is completed in the section with preload preloading), it is buried in the design position of the monitoring section through measurement, with a burial depth of 0.3m, and the pile is anchored with M30 cement mortar 0.15m around it, 5mm higher than the buried surface, and the surface is well treated for rust prevention. After the burial is completed, the pile top elevation is measured according to the national second-class precision leveling measurement standard as the initial reading. Observation frequency: 3 times a day, observation for one month.

[0061] Observation requirements: (1) The foundation piles used to observe displacement and settlement must be placed in a stable foundation that is not affected by the fill load. Effective measures must be taken to protect the foundation piles and displacement observation piles during the observation period.

[0062] (2) Filling observation control standard: The ground settlement rate of the centerline of the embankment shall not exceed 1.0 cm per day and night, and the horizontal displacement rate of the slope foot shall not exceed 0.5 cm per day and night. If this limit is exceeded, filling should be stopped immediately, and filling can be resumed after the observed value returns to below the limit value. The filling rate should be mainly controlled by horizontal displacement.

[0063] 2. Stability: The compaction of the roadbed is tested by the pit digging and sand filling method in accordance with JTG E60-2008 "Field Test Procedures for Highway Roadbed and Pavement".

[0064] The post-construction settlement and compaction degree of the roadbeds of Examples 1 to 3 and Comparative Examples 1 to 4 were tested, and the test results are shown in Table 1.

[0065] Table 1 From the test results in Table 1, it can be seen that the roadbed treatment structures of Examples 1 to 3 have small settlement after construction and high compaction degree, which indicates that the roadbed treatment structures of Examples 1 to 3 can effectively suppress roadbed settlement and improve roadbed stability.

[0066] The composite drainage layer of comparative example 1 has no vertical drainage sand well. After its construction, the post-construction settlement of the roadbed increases significantly, the compaction degree decreases significantly, and the stability decreases.

[0067] The anti-seepage waterproofing layer of Comparative Example 2 is a commercially available HDPE geomembrane. After its construction, the post-construction settlement of the roadbed increased and the compaction degree decreased.

[0068] In Comparative Example 3, no polyacrylic acid intercalated hydrotalcite was added to the HDPE geomembrane of the anti-seepage and waterproof layer. After its construction, the post-construction settlement of the roadbed increased and the compaction degree decreased.

[0069] The composite reinforcement layer of Example 4 has no prestressed pipe piles, and the post-construction settlement of the roadbed after construction is significantly increased, and the compaction degree is significantly reduced.

[0070] Embodiments 4 to 9 Example 4 The difference between Example 4 and Example 2 is that in the composite drainage layer of Example 4, the average particle size of crushed stone is 20 mm, and the average particle size of sand and gravel is 5 mm.

[0071] Example 5 The difference between Example 5 and Example 2 is that in the composite drainage layer of Example 5, the average particle size of crushed stone is 40 mm, and the average particle size of sand and gravel is 20 mm.

[0072] Example 6 The difference between Example 6 and Example 2 is that in step S3 of the construction process of Example 6, the thickness of the crushed stone layer is 20 cm, and the thickness of the sand and gravel layer is 10 cm.

[0073] Example 7 The difference between Example 7 and Example 2 is that in step S3 of the construction process of Example 7, the thickness of the crushed stone layer is 30 cm, and the thickness of the sand and gravel layer is 20 cm.

[0074] Example 8 The difference between Example 8 and Example 2 is that in step S7 of the construction process of Example 8, the thickness of the precast concrete is 10 cm.

[0075] Example 9 The difference between Example 9 and Example 2 is that in step S7 of the construction process of Example 9, the thickness of the precast concrete is 20 cm.

[0076] The post-construction settlement and compaction degree of the roadbed after construction of Examples 4 to 9 were tested, and the test results are shown in Table 2.

[0077] Table 2 Post-construction settlement / mm Compaction degree / % Example 4 10.1 99.0 Example 5 10.3 98.8 Example 6 10.5 98.7 Example 7 10.2 99.1 Example 8 10.4 99.0 Example 9 10.1 99.1 From the test results in Table 2, it can be seen that the difference between Example 4 and Example 5 and Example 2 is that the average particle sizes of crushed stone and sand are different. Among them, the compaction degree and stability of the roadbed after construction of Example 2 are the highest.

[0078] The difference between Example 6 and Example 7 and Example 2 is that the thickness of the crushed stone layer and the sand and gravel layer are different. Among them, after the construction of Example 2, the post-construction settlement of the roadbed is the smallest, the compaction degree is the highest, and the stability is the highest.

[0079] The difference between Example 8 and Example 9 and Example 2 is that the thickness of the precast concrete is different. Among them, the post-construction settlement of the roadbed after the construction of Example 2 is the smallest, the compaction degree is the highest, and the stability is the highest.

[0080] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A high water level roadbed treatment structure, characterized in that: It includes a composite drainage layer, an anti-seepage waterproof layer, a composite reinforcement layer and a protective layer; The composite drainage layer includes a vertical drainage body and a horizontal drainage layer, and the horizontal drainage layer is crushed stone and sand; The anti-seepage waterproof layer is a HDPE geomembrane, and the raw material composition of the HDPE geomembrane includes, by weight: 90-110 parts of high-density polyethylene, 10-20 parts of chlorinated polyethylene, 2-8 parts of carbon black, 1-2 parts of polyacrylic acid intercalated hydrotalcite, 1-2 parts of antioxidant, 0.5-1 part of anti-aging agent and 0.5-1 part of stabilizer; The composite reinforcement layer includes geogrids and prestressed pipe piles; The protective layer is precast concrete.

2. The high water level roadbed treatment structure according to claim 1, characterized in that: In the composite drainage layer, the vertical drainage body is a sand well.

3. The high water level roadbed treatment structure according to claim 1, characterized in that: In the composite drainage layer, the average particle size of crushed stone is 20-40 mm, and the average particle size of sand and gravel is 5-20 mm.

4. The high water level roadbed treatment structure according to claim 1, characterized in that: In the HDPE geomembrane, the antioxidant is selected from at least one of the antioxidant BHT, antioxidant 1010 and antioxidant DLTP.

5. The high water level roadbed treatment structure according to claim 1, characterized in that: In the HDPE geomembrane, the anti-aging agent is selected from at least one of antioxidant 264, antioxidant D and antioxidant IPPD.

6. The high water level roadbed treatment structure according to claim 1, characterized in that: In the HDPE geomembrane, the stabilizer is selected from at least one of tribasic lead sulfate, dibasic lead phosphite and dibasic lead stearate.

7. The high water level roadbed treatment structure according to claim 1, characterized in that: The preparation method of the HDPE geomembrane is: Step 1: mixing the high-density polyethylene and chlorinated polyethylene to prepare a premix; Step 2: adding the carbon black, polyacrylic acid intercalated hydrotalcite, antioxidant, anti-aging agent and stabilizer to the premix, mixing to obtain a mixture; Step 3: Extruding the mixture through an extruder and blowing a film to obtain the HDPE geomembrane.

8. A construction process for a high water level roadbed treatment structure according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Clear weeds, trees, stones and other obstacles in the construction area, level the ground, and dig drainage ditches on both sides of the roadbed; S2. Sand wells are driven into the soft soil layer as vertical drainage bodies. The spacing between the sand wells is 1.5~2.5m and the insertion depth is 5~10m. S3, laying a gravel layer, compacting it mechanically, laying a sand and gravel layer, compacting it mechanically, and forming a composite drainage layer; S4. Lay HDPE geomembrane on the composite drainage layer and weld the seams to form an anti-seepage waterproof layer; S5. Lay geogrids on the anti-seepage waterproof layer in 2 to 3 layers, with the overlap length of geogrids being 30 to 50 cm; S6. Drive prestressed pipe piles at a spacing of 1.5 to 3 m to form a composite reinforcement layer; S7. Lay precast concrete on top of the composite reinforcement layer to form a protective layer.

9. The construction process of the high water level roadbed treatment structure according to claim 8, characterized in that: In step S3, the thickness of the gravel layer is 20-30 cm, and the thickness of the sandstone layer is 10-20 cm.

10. The construction process of the high water level roadbed treatment structure according to claim 8, characterized in that: In step S7, the thickness of the precast concrete is 10-20 cm.

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