Multilayer composite structure highway subgrade and construction method thereof

Abstract

The invention belongs to the technical field of highways, and particularly relates to a multi-layer composite structure highway subgrade and a construction method thereof.The multi-layer composite structure highway subgrade comprises a cushion layer, a soil base layer is arranged on the upper portion of the cushion layer, a reinforcing assembly and a gravel layer are arranged on the upper portion of the soil base layer, and a covering assembly is arranged in the gravel layer; a slope is arranged on the side edge of the soil base layer, a drainage assembly is arranged in the slope, a coarse asphalt layer is arranged on the upper portion of the gravel layer, and a fine asphalt layer is arranged on the upper portion of the coarse asphalt layer. The reinforcing assembly and the covering assembly are used in a combined mode, the covering assembly is arranged on the upper portion of the soil base layer to cover the soil base layer for water prevention, and the drainage assembly and the covering assembly are used in a matched mode. Effective protection of the subgrade lower layer can be realized, so that the problem of subgrade loosening caused by infiltration of rainwater and underground water is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of highways, and in particular relates to a multi-layer composite structure highway subgrade and a construction method thereof. Background Art

[0002] The roadbed is the foundation of the road surface. It is a geotechnical structure formed by excavation or filling. The main function of the roadbed is to provide necessary conditions for road paving and train or vehicle operation, and to bear the static and dynamic loads of tracks and locomotives or road surfaces and traffic loads, while transmitting and diffusing the loads deep into the foundation. The structural performance of the roadbed is crucial to the safety of driving roads.

[0003] In a Chinese invention patent application with application publication number CN111794033A and application publication date 2020.10.20, a highway subgrade structure that can prevent subgrade softening is disclosed, including a subgrade, and the subgrade includes an asphalt mastic crushed stone mixture pavement layer, a medium-grained asphalt concrete layer is arranged at the lower end of the asphalt mastic crushed stone mixture pavement layer, a coarse-grained asphalt concrete layer is arranged at the lower end of the medium-grained asphalt concrete layer, a cement-stabilized crushed stone base layer is arranged at the lower end of the coarse-grained asphalt concrete layer, a cement-stabilized gravel subbase layer is arranged at the lower end of the cement-stabilized crushed stone base layer, a compacted soil base layer is arranged at the lower end of the cement-stabilized gravel subbase layer, and a square integral structure is formed between all horizontal columns and vertical columns through the arrangement of a first connecting column, a second connecting column and a third connecting column, so that the entire subgrade structure forms a square integral structure, thereby improving the integrity of the subgrade, and effectively reinforcing the subgrade, so that the subgrade has stronger bearing capacity and higher structural integrity, thereby effectively preventing subgrade softening and further preventing and controlling the softening of the highway subgrade. However, since the lower layer of the foundation is mostly soil and gravel, although it is compacted during the roadbed construction, as time goes by, rainwater and groundwater will gradually penetrate into the foundation and soak the soil and gravel, causing the roadbed to loosen. Therefore, the structure of the roadbed needs to be optimized. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a multi-layer composite structure highway roadbed and its construction method in view of the shortcomings of the prior art. The present invention can achieve effective protection of the lower layer of the roadbed, thereby solving the problem of loose roadbed caused by rainwater and groundwater infiltration.

[0005] This solution is achieved through the following technical measures: a multi-layer composite structure highway roadbed, including a cushion layer, a soil base layer is arranged on the upper part of the cushion layer, a reinforcement component and a crushed stone layer are arranged on the upper part of the soil base layer, a covering component is arranged inside the crushed stone layer, a side slope is arranged on the side of the soil base layer, a drainage component is arranged inside the side slope, a coarse asphalt layer is arranged on the upper part of the crushed stone layer, and a fine asphalt layer is arranged on the upper part of the coarse asphalt layer; The reinforcement component is used in combination with the covering component. The covering component is arranged on the upper part of the soil base layer to cover and waterproof the soil base layer. The drainage component is used in conjunction with the covering component.

[0006] Preferably, the reinforcement assembly includes a civil grid arranged on the upper surface of the soil base layer, steel rods are interspersed on the upper part of the soil base layer, the outer surface of the steel rods is fixedly sleeved with a ring, the outer surface of the ring is provided with L-shaped positioning blocks distributed in a circular matrix, and the bottom end of the steel rod is fixedly connected to a pointed cone.

[0007] Preferably, the lower surface of the collar abuts against the upper surface of the civil grid, the bottom end of the vertical section of the L-shaped positioning block is inserted into the interior of the soil base, and the horizontal section of the L-shaped positioning block is pressed onto the upper part of the horizontal and vertical rods of the civil grid.

[0008] Preferably, the covering assembly includes a step-type plate arranged on the upper part of the soil base layer, the side of the step-type plate is fixedly connected with an extension plate, a strip plate is arranged on the side of the extension plate away from the step-type plate, and the upper surfaces of the strip plate and the extension plate are provided with a slot, and a U-shaped block is clamped inside the slot.

[0009] Preferably, a water seepage trough is provided on the side of the slope, the water seepage trough is arranged at a position directly opposite to the terrace profile plate, and a filter screen is arranged inside the water seepage trough.

[0010] Preferably, a mounting ring is fixedly connected to the lower surface of the strip plate, and the top end of the steel rod is clamped inside the mounting ring.

[0011] Preferably, the drainage component includes a drainage ditch that runs through the inside of the slope, a grille plate is arranged on the top of the drainage ditch, grooves are symmetrically arranged on two opposite inner walls of the drainage ditch, a baffle is arranged between the two grooves, one end of the baffle is hinged to the bottom of one of the grooves, and the other end is located in the other groove and is a free end, and a support rod is hinged to the lower surface of the free end of the baffle.

[0012] Preferably, a support is provided on the bottom inner wall of the groove, and slide grooves are opened on both sides of the support. The end of the support rod away from the baffle is fixedly connected to a slider, and the slider slides inside the slide groove. The bottom end of the slider is fixedly connected to a spring.

[0013] Preferably, a partition plate is fixedly connected to the inner wall of the drainage ditch, a drainage pipe is inserted and fixed inside the drainage ditch, an axle rod is movably connected to the inner wall of the drainage pipe, a circular plate is fixedly connected to the outer surface of the axle rod, and a counterweight block is arranged at the bottom of the circular plate.

[0014] The present invention also provides a construction method for the above-mentioned multi-layer composite structure highway roadbed, comprising the following steps: S1. Lower layer laying: first lay the cushion layer and compact it, then lay the soil base layer on the cushion layer and compact it, then lay the earth grid on the soil base layer, and then lay a thin layer of crushed stones to cover the earth grid; S2. Slope construction: construct slopes on both sides of the roadbed and install drainage components during the construction process; S3, middle layer laying: after marking and positioning, all steel rods are driven into the soil base, and then the steel rods are covered with crushed stones. Then the strip plates are installed on the top of the steel rods, and the terraced plates are installed on the sides of the strip plates. Finally, the covering components are buried and compacted with crushed stones. S4. Upper layer paving: Coarse asphalt is laid on the upper part of the gravel layer. After the coarse asphalt layer is compacted until there is no obvious trace, a fine asphalt layer is laid on the upper part and compacted again to complete the paving of the roadbed.

[0015] Beneficial effects of the present invention: 1. The present invention arranges a reinforcement component on the upper part of the soil base, covers the surface of the soil base with a civil grid, inserts a steel rod from the gravel layer into the soil base, and compacts and positions the civil grid through a collar and an L-shaped positioning block, thereby improving the shear strength and overall stability of the soil and reducing settlement; 2. The present invention arranges the covering component inside the gravel layer, and the covering component is a continuous terraced structure, which can improve the compressive strength of the gravel layer and effectively prevent the gravel layer from sinking into the soil base. At the same time, the low-lying part of the terraced plate is connected to the seepage trough, and the rainwater that penetrates into the gravel layer can be discharged into the slope, thereby preventing the rainwater from infiltrating into the roadbed and improving the overall waterproof effect of the roadbed; 3. The present invention arranges the drainage component in the slope, and utilizes the one-way flipping function of the baffle to discharge the rainwater on the ground and the rainwater infiltrated by the gravel layer. Then, through the cooperation with the partition plate, the drainage pipe and other structures, the water rising from the underground can be diverted and discharged from the drainage pipe, blocking the groundwater from entering the roadbed. The rainwater can be discharged while effectively preventing the groundwater from entering the roadbed, thereby improving the anti-seepage effect of the roadbed and further increasing the service life of the roadbed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the three-dimensional structure of the multi-layer composite structure highway roadbed in the present invention; Figure 2 The local cross-section structure of the multi-layer composite structure highway roadbed in the present invention is shown in FIG. Figure 1 ; Figure 3 The local cross-section structure of the multi-layer composite structure highway roadbed in the present invention is shown in FIG. Figure 2 ; Figure 4 It is a schematic diagram of the structure of the covering component in the present invention; Figure 5 It is a structural schematic diagram of the reinforcement component in the present invention; Figure 6 It is a schematic diagram of the overall structure of the slope in the present invention; Figure 7 It is a schematic diagram of the internal structure of the slope in the present invention; Figure 8 for Figure 7 The enlarged view of point A in the middle; Fig. 9 It is a schematic diagram of the structure of the drainage pipe in the present invention.

[0017] The markings in the figure are: 1. cushion layer; 2. soil base layer; 3. gravel layer; 4. slope; 5. reinforcement components; 501. civil grid; 502. steel rod; 503. collar; 504. L-shaped positioning block; 505. pointed cone; 506. mounting ring; 6. covering components; 601. terrace plate; 602. extension plate; 603. slot; 604. U-shaped block; 605. strip plate; 606. seepage trough; 607, filter screen; 7, coarse asphalt layer; 8, fine asphalt layer; 9, drainage assembly; 901, drainage ditch; 902, grille plate; 903, groove; 904, partition plate; 905, baffle; 906, support rod; 907, support; 908, slide; 909, slider; 910, spring; 911, drain pipe; 912, shaft rod; 913, round plate; 914, counterweight. DETAILED DESCRIPTION

[0018] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0019] like Figures 1 to 9As shown, the multi-layer composite structure highway roadbed includes a cushion layer 1, a soil base layer 2 is arranged on the upper part of the cushion layer 1, a reinforcement component 5 and a crushed stone layer 3 are arranged on the upper part of the soil base layer 2, and a covering component 6 is arranged inside the crushed stone layer 3. A slope 4 is arranged on the side of the soil base layer 2 to maintain water and soil balance and improve the stability of the roadbed body. A drainage component 9 is arranged inside the slope 4, a coarse asphalt layer 7 is arranged on the upper part of the crushed stone layer 3, and a fine asphalt layer 8 is arranged on the upper part of the coarse asphalt layer 7. The reinforcement component 5 is used in combination with the covering component 6, which is arranged on the upper part of the soil base layer 2 to cover and waterproof the soil base layer 2, and the drainage component 9 is used in conjunction with the covering component 6.

[0020] A reinforcement component 5 is provided between the soil base layer 2 and the gravel layer 3 to improve the shear strength and overall stability of the soil and reduce soil settlement. A covering component 6 is provided in the gravel layer 3 to block and divert water that penetrates into the gravel layer 3 while improving the compressive strength of the gravel layer 3. At the same time, in conjunction with a drainage component 9 provided in the slope 4, water accumulated on the road surface and water that penetrates into the roadbed can be discharged, and the backflow of groundwater can also be prevented.

[0021] like Figure 2 , Figure 3 and Figure 5 As shown, the reinforcement component 5 includes a civil grid 501 arranged on the upper surface of the soil base layer 2, a steel rod 502 is interspersed in the upper part of the soil base layer 2, a ring 503 is fixedly sleeved on the outer surface of the steel rod 502, and L-shaped positioning blocks 504 are distributed in a ring matrix on the outer surface of the ring 503, a pointed cone 505 is fixedly connected to the bottom end of the steel rod 502, the lower surface of the ring 503 abuts against the upper surface of the civil grid 501, the bottom end of the vertical section of the L-shaped positioning block 504 is inserted into the interior of the soil base layer 2, and the horizontal section of the L-shaped positioning block 504 is pressed on the upper part of the horizontal and vertical rods of the civil grid 501.

[0022] The civil engineering grid 501 covers the upper surface of the soil base layer 2, improving the cohesion of the soil base layer 2. The steel rod 502 is inserted into the soil base layer 2 from the gravel layer 3. The civil engineering grid 501 is compacted and positioned by the ring 503 and the L-shaped positioning block 504, thereby improving the shear strength and overall stability of the soil and reducing soil settlement.

[0023] like Figure 3 , Figure 4 and Figure 5As shown, the covering assembly 6 includes a step-type plate 601 arranged on the upper part of the soil base layer 2, and the side of the step-type plate 601 is fixedly connected with an extension plate 602, and a strip plate 605 is arranged on the side of the extension plate 602 away from the step-type plate 601, and the upper surfaces of the strip plate 605 and the extension plate 602 are both provided with a slot 603, and the inside of the slot 603 is clamped with a U-shaped block 604, and the side of the slope 4 is provided with a seepage groove 606, which is arranged at a position opposite to the step-type plate 601, and the inside of the seepage groove 606 is provided with a filter screen plate 607, and the lower surface of the strip plate 605 is fixedly connected with a mounting ring 506, and the top of the steel rod 502 is clamped inside the mounting ring 506.

[0024] The strip plate 605 is fixed to the top of the steel rod 502 by means of the mounting ring 506, and then the extension plate 602 is spliced ​​with the strip plate 605, and the U-shaped block 604 is inserted into the slot 603 on the surface of the extension plate 602 and the strip plate 605 to realize the connection between the strip plate 605 and the extension plate 602, and the reinforcement component 5 is connected with the covering component 6, so as to improve the overall strength and effectively disperse the pressure. At the same time, the covering component 6 is arranged as a whole inside the gravel layer 3, and the covering component 6 is a continuous terraced structure, which can improve the compressive strength of the gravel layer 3 and effectively prevent the gravel layer 3 from sinking into the soil base layer 2. At the same time, the low-lying part of the terraced plate 601 is connected with the seepage trough 606, so that the rainwater that penetrates into the gravel layer 3 can be discharged into the slope 4, so as to prevent the damage of the roadbed to the roadbed by the infiltration of rainwater and improve the overall waterproof effect of the roadbed.

[0025] like Figures 6 to 9As shown, the drainage component 9 includes a drainage groove 901 that runs through and is opened inside the slope 4, a grille plate 902 is arranged on the top of the drainage groove 901, grooves 903 are symmetrically opened on two opposite inner side walls of the drainage groove 901, a baffle 905 is arranged between the two grooves 903, one end of the baffle 905 is hinged to the bottom of one of the grooves 903, and the other end is located in the other groove 903 and is a free end, a support rod 906 is hinged on the lower surface of the free end of the baffle 905, a support 907 is arranged on the bottom inner wall of the groove 903, and slide grooves 908 are opened on both sides of the support 907, and a slider 909 is fixedly connected to one end of the support rod 906 away from the baffle 905, and the slider 909 slides inside the slide groove 908, and the bottom end of the slider 909 is fixedly connected to Spring 910, when spring 910 is in a natural state, the upper end surface of baffle 905 contacts the upper end surface of groove 903 to prevent rainwater leakage, the inner wall of drainage groove 901 is fixedly connected with partition plate 904, the top end of partition plate 904 is lower than the lower surface of grille plate 902 and higher than the upper inner wall of groove 903, the bottom end of partition plate 904 is lower than the lower inner wall of groove 903, the interior of drainage groove 901 is fixedly inserted with drainage pipe 911, drainage pipe 911 is arranged between two partition plates 904, and the top end of drainage pipe 911 is lower than the top end of partition plate 904, the inner wall of drainage pipe 911 is movably connected with shaft rod 912, the outer surface of shaft rod 912 is fixedly connected with circular plate 913, and the bottom of circular plate 913 is provided with counterweight block 914.

[0026] After the rainwater on the ground flows into the drainage ditch 901, part of it will accumulate at the top of the baffle 905, and part of it will be directly discharged to the ground from the drain port between the partition plates 904. When the gravity of the rainwater on the top of the baffle 905 is greater than the supporting elastic force of the spring 910, the baffle 905 will be pushed to flip downward, and the slider 909 will be pushed by the support rod 906 to slide in the slide groove 908 on both sides of the support 907 and squeeze the spring 910. After the rainwater is discharged, the spring 910 rebounds and pushes the baffle 905 to reset and re-close. The rainwater that penetrates into the roadbed is blocked by the covering component 6 and can only flow to the upper part of the baffle 905 through the seepage groove 606, which can facilitate the discharge of rainwater that penetrates into the roadbed and block the water rising from the ground. Specifically, if groundwater seeps upward, the groundwater will be blocked by the baffle 905 and concentrated to flow between the partition plates 904, and finally enter the drain pipe 911. The water flow in the drain pipe 911 will push the circular plate 913 to flip around the shaft 912, thereby discharging the upwelling groundwater and preventing the groundwater from entering the roadbed. After the water is discharged, the flap 913 rotates to a vertical state under the action of the counterweight block 914, which can block the entry of debris, thereby achieving the discharge of rainwater and effectively preventing groundwater from entering the roadbed, thereby improving the anti-seepage effect of the roadbed and thus increasing the service life of the roadbed.

[0027] The present invention also provides a construction method for the above-mentioned multi-layer composite structure highway roadbed, comprising the following steps: S1. Lower layer laying: first lay the cushion layer 1 and compact it, then lay the soil base layer 2 on the cushion layer 1 and compact it, then lay the civil engineering grid 501 on the soil base layer 2, and then lay a thin layer of crushed stones to cover the civil engineering grid 501, and use the crushed stones to completely cover and flatten the civil engineering grid 501, so that the civil engineering grid 501 can be completely compacted on the upper surface of the soil base layer 2; S2, construction of side slope 4: constructing side slope 4 on both sides of the roadbed, and installing drainage components 9 during the construction process; S3, middle layer laying: after marking and positioning, all the steel rods 502 are driven into the soil base 2, and then the steel rods 502 are covered with crushed stones, and then the strip plates 605 are installed on the top of the steel rods 502, and then the terraced plate 601 is installed on the side of the strip plate 605, and finally the covering assembly 6 is buried and compacted with crushed stones; S4, upper layer paving: coarse asphalt is laid on the upper part of the crushed stone layer 3, and after the coarse asphalt layer 7 is compacted until there is no obvious trace, a fine asphalt layer 8 is laid on the upper part, and compacted again to complete the paving of the roadbed.

[0028] The main body of the roadbed in the present invention includes a cushion layer 1, a soil base layer 2, a crushed stone layer 3, a coarse asphalt layer 7 and a fine asphalt layer 8. Slopes 4 are arranged on both sides to maintain water-soil balance and improve the stability of the main body of the roadbed. A covering component 6 is arranged in the crushed stone layer 3. While improving the compressive strength of the crushed stone layer 3, it can block and divert water that penetrates into the crushed stone layer 3. At the same time, in conjunction with a drainage component 9 arranged in the slope 4, it can discharge water accumulated on the road surface and water that penetrates into the roadbed, and at the same time, it can prevent the backflow of groundwater. After the roadbed is laid, a civil grid 501 is laid between the crushed stone layer 3 and the soil base layer 2. The civil grid 501 covers the upper surface of the soil base layer 2, which improves the cohesion of the soil base layer 2. The steel rod 502 is inserted from the crushed stone layer 3 into the soil base layer 2. The civil grid 501 is pressed and positioned by the ring 503 and the L-shaped positioning block 504, which improves the shear strength and overall stability of the soil and reduces settlement. During the installation of the covering assembly 6, the strip plate 605 is clamped and fixed to the top of the steel rod 502 through the mounting ring 506, and then the step-type plate 601 is spliced ​​with the strip plate 605, and the U-shaped clamping block 604 is inserted into the clamping groove 603 on the surface of the extension plate 602 and the strip plate 605 to achieve the connection between the strip plate 605 and the step-type plate 601, and the reinforcement assembly 5 is connected to the covering assembly 6 to improve the overall strength and effectively disperse the pressure. At the same time, the covering assembly 6 is set as a whole inside the gravel layer 3. The covering component 6 is a continuous terraced structure, which can improve the compressive strength of the gravel layer 3 and effectively prevent the gravel layer 3 from sinking into the soil base 2. At the same time, the low-lying part of the terraced plate 601 is connected to the seepage trough 606, which can discharge rainwater that penetrates into the gravel layer 3 into the slope 4, avoiding the damage of rainwater infiltration to the roadbed and improving the overall waterproof effect of the roadbed. In addition, the detachable type of the reinforcement component 5 and the covering component 6 also facilitates subsequent disassembly and secondary utilization, saving resources.

[0029] The drainage assembly 9 inside the slope 4 can discharge the accumulated water on the road surface and the seepage water inside the roadbed simultaneously. The interior of the drainage ditch 901 is separated by the partition plate 904, and the baffle plate 905 is used to block the drainage ditch 901. If groundwater seeps upward, the groundwater will be blocked by the baffle plate 905 and flow into the space between the partition plates 904, and finally enter the drainage pipe 911. The water flow in the drainage pipe 911 will push the circular plate 913 to flip around the shaft 912, so as to discharge the upwelling groundwater and prevent the groundwater from entering the roadbed. After the water is discharged, the flap 913 is moved under the action of the counterweight block 914. By rotating it downward to a vertical state, it can block the entry of debris. After the rainwater on the ground flows into the drainage ditch 901, it will accumulate at the top of the baffle 905. When the gravity of the rainwater is greater than the supporting elastic force of the spring 910, the baffle 905 will be pushed to flip downward, and the slider 909 will be pushed by the support rod 906 to slide in the slide groove 908 on both sides of the support 907 and squeeze the spring 910. After the rainwater is discharged, the spring 910 rebounds and pushes the baffle 905 to reset and re-close it. This achieves the discharge of rainwater while effectively preventing groundwater from entering the roadbed, thereby improving the anti-seepage effect of the roadbed and thus increasing the service life of the roadbed.

[0030] Technical features not described in the present invention can be implemented by existing technologies and will not be described in detail here. The present invention is not limited to the above specific embodiments, and changes, modifications, additions or substitutions made by ordinary technicians in the field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A multi-layer composite structure highway subgrade, characterized in that: include: A cushion layer (1), wherein a soil base layer (2) is arranged on the upper part of the cushion layer (1), a reinforcement component (5) and a gravel layer (3) are arranged on the upper part of the soil base layer (2), a covering component (6) is arranged inside the gravel layer (3), a side slope (4) is arranged on the side of the soil base layer (2), a drainage component (9) is arranged inside the side slope (4), a coarse asphalt layer (7) is arranged on the upper part of the gravel layer (3), and a fine asphalt layer (8) is arranged on the upper part of the coarse asphalt layer (7); The reinforcement component (5) is used in combination with the covering component (6); the covering component (6) is arranged on the upper part of the soil base layer (2) to cover the soil base layer (2) for waterproofing; and the drainage component (9) is used in combination with the covering component (6).

2. The multi-layer composite structure highway subgrade according to claim 1, characterized in that: The reinforcement assembly (5) comprises a civil grid (501) arranged on the upper surface of a soil base layer (2); a steel rod (502) is inserted into the upper portion of the soil base layer (2); a collar (503) is fixedly sleeved on the outer surface of the steel rod (502); L-shaped positioning blocks (504) are distributed in a circular matrix on the outer surface of the collar (503); and a pointed cone (505) is fixedly connected to the bottom end of the steel rod (502).

3. The multi-layer composite structure highway subgrade according to claim 2 is characterized in that: The lower surface of the collar (503) abuts against the upper surface of the civil grid (501), the bottom end of the vertical section of the L-shaped positioning block (504) is inserted into the interior of the soil base (2), and the horizontal section of the L-shaped positioning block (504) is pressed onto the upper parts of the horizontal and vertical rods of the civil grid (501).

4. The multi-layer composite structure highway subgrade according to claim 3 is characterized in that: The covering assembly (6) comprises a step-shaped plate (601) arranged on the upper part of the soil base layer (2); an extension plate (602) is fixedly connected to the side of the step-shaped plate (601); a strip plate (605) is arranged on the side of the extension plate (602) away from the step-shaped plate (601); a slot (603) is provided on the upper surfaces of the strip plate (605) and the extension plate (602); a U-shaped block (604) is clamped inside the slot (603).

5. The multi-layer composite structure highway subgrade according to claim 4 is characterized in that: A water seepage trough (606) is provided on the side of the side slope (4), the water seepage trough (606) is arranged at a position directly opposite to the step-type plate (601), and a filter screen plate (607) is arranged inside the water seepage trough (606).

6. The multi-layer composite structure highway subgrade according to claim 5, characterized in that: A mounting ring (506) is fixedly connected to the lower surface of the strip plate (605), and the top end of the steel rod (502) is clamped inside the mounting ring (506).

7. The multi-layer composite structure highway subgrade according to claim 6, characterized in that: The drainage assembly (9) comprises a drainage groove (901) extending through the inside of the slope (4); a grille plate (902) is arranged on the top of the drainage groove (901); grooves (903) are symmetrically arranged on two opposite inner side walls of the drainage groove (901); a baffle (905) is arranged between the two grooves (903); one end of the baffle (905) is hinged to the bottom of one of the grooves (903); the other end is located in the other groove (903) and is a free end; a support rod (906) is hinged to the lower surface of the free end of the baffle (905).

8. The multi-layer composite structure highway subgrade according to claim 7, characterized in that: A support (907) is provided on the inner wall at the bottom of the groove (903), and slide grooves (908) are provided on both sides of the support (907). A slider (909) is fixedly connected to one end of the support rod (906) away from the baffle (905), and the slider (909) slides inside the slide groove (908). A spring (910) is fixedly connected to the bottom end of the slider (909).

9. A construction method for a multi-layer composite structure highway subgrade according to any one of claims 1 to 9, characterized in that: The steps include: S1, laying the lower layer: first laying the cushion layer (1) and compacting it, then laying the soil base layer (2) on the upper part of the cushion layer (1) and compacting it, then laying the earth grid (501) on the upper part of the soil base layer (2), and then laying a thin layer of crushed stones to cover the earth grid (501); S2, construction of side slope (4): constructing side slopes (4) on both sides of the roadbed, and installing drainage components (9) during the construction process; S3, middle layer laying: after marking and positioning, all the steel rods (502) are driven into the soil base layer (2), and then the steel rods (502) are covered with crushed stones, and then the strip plates (605) are installed on the top of the steel rods (502), and then the terraced plate (601) is installed on the side of the strip plate (605), and finally the covering assembly (6) is buried and compacted with crushed stones; S4, upper layer paving: coarse asphalt is laid on the upper part of the crushed stone layer (3), and after the coarse asphalt layer (7) is compacted until no obvious traces are left, a fine asphalt layer (8) is laid on the upper part, and compacted again to complete the paving of the roadbed.

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