A pile-slab retaining wall concealed wall back drainage structure and a construction method thereof

Abstract

The present application relates to a kind of pile board type retaining wall concealed wall back drainage structure and its construction method, comprising: retaining wall main body, embedded pipe, upward inclined type water-permeable pipe, vertical water guide pipe, drainage device, filter layer and baffle.Pre-embedded pipe is vertically arranged in the interior of retaining wall main body.Upward inclined type water-permeable pipe is inserted in soil body obliquely upwards, and lower end is communicated with embedded pipe.Vertical water guide pipe is arranged in embedded pipe, and a plurality of first water-permeable holes are formed in vertical water guide pipe, and filter layer is arranged between embedded pipe and vertical water guide pipe.Baffle is arranged in the side of retaining wall main body close to road.Drainage device is arranged in the side of retaining wall main body close to road, and vertical water guide pipe is communicated with drainage device.The present application is communicated by embedded pipe, upward inclined type water-permeable pipe, vertical water guide pipe and drainage device, so that wall back groundwater is drained to drainage side ditch after being collected, and the problems of wall surface pollution, landscape destruction, and wet and slippery water of sidewalk, etc. passing safety problem caused by traditional water release pipe exposure are avoided.

Description

Technical Field

[0001] The invention relates to the field of retaining wall technology, and in particular to a concealed drainage structure for a pile-slab retaining wall and its construction method. Background Technology

[0002] With the continuous improvement of urban transportation networks, newly constructed roads often require retaining walls to avoid large-scale excavation behind them due to their proximity to existing buildings, elevation constraints, or land use boundaries. However, groundwater behind the wall can have a significant adverse impact on the retaining wall structure. Increased water pressure can lead to increased wall load, deformation, displacement, and other defects, threatening the safety of the structure behind the wall. To eliminate these hazards, drainage pipes are typically installed within the wall to actively drain the groundwater behind it.

[0003] Traditional drainage systems expose drainage pipes directly on the retaining wall surface, allowing groundwater to flow freely along the wall after discharge. Over time, the water carries silt and impurities that adhere to the wall surface, causing pollution, facade damage, and negatively impacting the urban roadscape, while also increasing maintenance difficulty and costs. Furthermore, the continuous flow of groundwater constantly soaks surrounding sidewalks, leading to slippery surfaces and water accumulation, posing safety hazards to pedestrians. Therefore, a novel wall-backed drainage system is urgently needed to replace the direct wall-facing drainage method, ensuring structural safety, pedestrian safety, and a pleasant urban landscape. Summary of the Invention

[0004] The purpose of this invention is to provide a concealed drainage structure and construction method for pile-slab retaining walls, which can solve the problems of landscape pollution and slippery sidewalks caused by exposed drainage pipes in traditional drainage structures.

[0005] To achieve the above objectives, an invention discloses a concealed drainage structure for a pile-slab retaining wall, comprising: a retaining wall body, a pre-embedded pipe, an inclined permeable pipe, a vertical guide pipe, a drainage device, a filter layer, and a baffle. The pre-embedded pipe is vertically installed inside the retaining wall body. The inclined permeable pipe is inserted obliquely upwards into the soil, and its lower end is connected to the pre-embedded pipe. The vertical guide pipe is installed inside the pre-embedded pipe, and has several first permeable holes. The filter layer is installed between the pre-embedded pipe and the vertical guide pipe. The baffle is installed on the side of the retaining wall body closest to the road. The drainage device is installed on the side of the retaining wall body closest to the road, and the lower end of the vertical guide pipe is connected to the drainage device.

[0006] Preferably, the pre-embedded pipe is installed on the side of the retaining wall body close to the road, and a through groove is opened on the side of the retaining wall body. The through groove connects to the inside of the pre-embedded pipe, the through groove faces the road, the width of the through groove is greater than the diameter of the vertical water guide pipe, and an impermeable geomembrane is installed at the opening of the through groove.

[0007] Preferably, the retaining wall body includes reinforced concrete piles and plain concrete piles, the reinforced concrete piles and plain concrete piles are arranged alternately, and the pre-embedded pipe is set in the plain concrete pile.

[0008] Preferably, the embedded pipe is a corrugated pipe, and the embedded pipe extends downward to 40-60cm below the road surface.

[0009] Preferably, the vertical water guide pipe is wrapped with non-woven geotextile.

[0010] Preferably, the angle between the inclined permeable pipe and the horizontal plane is 8°~15°.

[0011] Preferably, the inclined permeable pipe has several second permeable holes arranged in four rows at the top, bottom, left, and right positions of the inclined permeable pipe. The second permeable holes at the top and bottom positions are symmetrically arranged, as are the second permeable holes at the left and right positions, and the second permeable holes at the top and bottom positions and the second permeable holes at the left and right positions are staggered. The inclined permeable pipe is wrapped with non-woven geotextile, which at least covers the second permeable holes. The lower end of the inclined permeable pipe extends 3-8 cm into the pre-buried pipe.

[0012] Preferably, the drainage device includes a longitudinal water guide pipe, a transverse water guide pipe, and a drainage ditch; the drainage ditch is located at the edge of the road and close to the main body of the retaining wall; the longitudinal water guide pipe is arranged along the length of the drainage ditch; the vertical water guide pipe is connected to the longitudinal water guide pipe; the transverse water guide pipe is spaced apart along the length of the longitudinal water guide pipe; one end of the transverse water guide pipe is connected to the longitudinal water guide pipe, and the other end is connected to the drainage ditch.

[0013] Preferably, it also includes a capping beam set on the top of the main body of the retaining wall, wherein a maintenance well is provided in the capping beam, the position of the maintenance well corresponds to the position of the pre-embedded pipe, and the maintenance well is connected to the pre-embedded pipe.

[0014] Preferably, a support member is provided between the vertical water guide pipe and the reverse filter layer, and the support member is used to support the reverse filter layer.

[0015] This invention also discloses a construction method for a concealed back-drainage structure of a pile-slab retaining wall, used to manufacture a concealed back-drainage structure for a pile-slab retaining wall, comprising the following steps: S1, constructing the main body of the retaining wall and its top cap beam; pre-embedding a vertical pre-embedded pipe on the side of the retaining wall closest to the road. S2, after the main body of the retaining wall reaches the design strength, excavating the soil in layers to the road design elevation. S3, determining the position of the pre-embedded pipe, and cutting a through groove along the side of the pre-embedded pipe. S4, drilling multiple installation holes at intervals inside the pre-embedded pipe, the installation holes being opened towards the direction away from the road of the main body of the retaining wall, and the installation holes being set in an upward oblique direction, the installation holes being set at multiple intervals of two meters in the vertical direction, and installing an inclined permeable pipe in the installation hole. S5, placing a vertical guide pipe wrapped with non-woven geotextile into the pre-embedded pipe, after the vertical guide pipe is buried, gradually backfilling the filter layer from bottom to top, and simultaneously pasting an impermeable geomembrane at the opening of the through groove. S6, construct the retaining wall baffle, and construct a drainage device at the bottom of the baffle so that the lower end of the vertical guide pipe is connected to the drainage device.

[0016] Preferably, in step S1, the retaining wall body includes reinforced concrete piles and plain concrete piles, which are alternately installed, with the plain concrete piles being constructed first and the reinforced concrete piles being constructed later; the embedded pipe is installed inside the plain concrete pile, and the embedded pipe extends downward to 40-60cm below the road surface.

[0017] Preferably, in step S4, several inclined permeable pipes are arranged at intervals along the vertical direction, with an angle of 8° to 15° with the horizontal plane, and the lower end of the inclined permeable pipe extends into the pre-buried pipe by 3 to 8 cm.

[0018] Preferably, in step S5, the impermeable geomembrane is an HDPE membrane, which is vertically arranged along the channel.

[0019] Preferably, in step S6, the construction drainage device specifically includes: pre-embedding a longitudinal water guide pipe at the bottom of the baffle along the road direction, connecting the lower end of the vertical water guide pipe to the longitudinal water guide pipe; setting several transverse water guide pipes at intervals along the length of the longitudinal water guide pipe, connecting one end of the transverse water guide pipe to the longitudinal water guide pipe; excavating a drainage ditch at the edge of the road, and introducing the other end of the transverse water guide pipe into the drainage ditch.

[0020] Preferably, in step S1, during the construction of the cap beam, a pipe fitting is pre-embedded in the cap beam at the position corresponding to the pre-embedded pipe, forming a maintenance well that communicates with the pre-embedded pipe.

[0021] Preferably, in step S5, before backfilling the filter layer, a support component needs to be installed outside the vertical guide pipe, and the support component is used to support the filter layer.

[0022] The invention has the following beneficial effects: 1. This invention involves vertically installing a pre-embedded pipe inside the main body of the retaining wall, fixing an inclined permeable pipe upwards inside the main body of the retaining wall with its lower end connected to the pre-embedded pipe, and connecting the lower end of the vertical guide pipe to a drainage device installed on the side of the main body of the retaining wall near the road. This allows groundwater behind the wall to be collected through the inclined permeable pipe and then discharged downwards along the vertical guide pipe inside the pre-embedded pipe, ultimately being concealed and discharged into the drainage ditch. This completely avoids the landscape problems such as wall pollution and facade damage caused by the direct discharge of traditional exposed drainage pipes, as well as the pedestrian safety hazards such as slippery road surface and water accumulation caused by groundwater overflowing and seeping into the sidewalk.

[0023] 2. This invention creates a step-by-step filtration structure by setting a vertical water guide pipe inside a pre-embedded pipe and setting a filter layer between the vertical water guide pipe and the pre-embedded pipe. This effectively prevents soil particles from entering the pipe with the water flow, avoids pipe blockage, and ensures the long-term smooth operation of the drainage system.

[0024] 3. This invention achieves replaceable installation of the vertical guide pipe by setting a capping beam at the top of the retaining wall and setting a maintenance well within the capping beam at the location of the pre-embedded pipe, allowing the upper end of the vertical guide pipe to extend into the maintenance well. When the pipe becomes blocked or ages, it can be directly replaced from the maintenance well without excavating the road surface or damaging the retaining wall structure, significantly reducing the difficulty and cost of later operation and maintenance. Attached Figure Description

[0025] Figure 1 This is a cross-sectional schematic diagram of the overall structure provided in a specific embodiment of the invention; Figure 2 This is a cross-sectional schematic diagram of AA provided in the first specific embodiment of the invention; Figure 3 This is a partially enlarged schematic diagram of point C provided in the first specific embodiment of the invention; Figure 4 This is a schematic diagram of the inclined permeable pipe provided in the first specific embodiment of the invention; Figure 5 This is a cross-sectional schematic diagram of an inclined permeable pipe wrapped with non-woven geotextile, as provided in the first specific embodiment of the invention. Figure 6 This is a cross-sectional schematic diagram of the inclined permeable pipe provided in the first specific embodiment of the invention; Figure 7 This is a partial schematic diagram of the embedded pipe installed in a plain concrete pile, as provided in a specific embodiment of the invention. Figure 8 This is a schematic diagram of the through groove provided in the first specific embodiment of the invention; Figure 9 This is a schematic diagram of the installation of the inclined permeable pipe provided in the first specific embodiment of the invention; Figure 10This is a schematic diagram of the installation of the vertical water guide pipe provided in the first specific embodiment of the invention; Figure 11 This is a schematic diagram of the installation of the filter layer and impermeable geotextile provided in the first specific embodiment of the invention; Figure 12 This is a longitudinal cross-sectional schematic diagram of the overall structure provided in the second specific embodiment of the invention; Figure 13 This is a cross-sectional schematic diagram of BB provided in the second specific embodiment of the invention.

[0026] Explanation of symbols for main components: 1. Main retaining wall; 11. Plain concrete pile; 12. Reinforced concrete pile; 2. Embedded pipe; 21. Filter layer; 22. Impermeable geomembrane; 23. Through trench; 3. Vertical guide pipe; 4. Inclined permeable pipe; 41. Second permeable hole; 42. Non-woven geotextile; 5. Baffle; 6. Drainage device; 61. Longitudinal guide pipe; 62. Transverse guide pipe; 63. Drainage ditch; 7. Road; 8. Crown beam; 81. Inspection well; 82. Manhole cover. Detailed Implementation

[0027] To make the purpose, technical solution, and advantages of the invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0028] Example 1 like Figures 1-11 This invention provides a concealed drainage structure for a pile-slab retaining wall, including a retaining wall body 1. The retaining wall body 1 is composed of alternating reinforced concrete piles 12 and plain concrete piles 11, forming a pile-slab retaining wall support system. A capping beam 8 is provided at the top of the retaining wall, connecting the tops of each support pile into a whole, enhancing the overall rigidity and deformation coordination of the retaining wall. A pre-embedded pipe 2 is vertically installed inside the retaining wall body 1 on the side closest to the road 7. The pre-embedded pipe 2 is a 30cm diameter HDPE corrugated pipe, with its top flush with the top surface of the retaining wall body 1 and its lower end extending approximately 50cm below the designed road surface. A vertical through groove 23 is axially formed on the side of the retaining wall body 1 facing the road 7. This through groove 23 connects to the interior of the pre-embedded pipe 2. The width of the through groove 23 is approximately 32cm, larger than the diameter of the vertical drainage pipe 3, facilitating the insertion of the vertical drainage pipe 3 from the groove opening. An impermeable geomembrane 22 is pasted at the opening of the trench. The impermeable geomembrane 22 is a 1.0mm thick HDPE membrane, which is set along the entire length of the trench 23. It can effectively prevent cement slurry from seeping into the filter layer 21 and causing blockage when the baffle 5 is poured, thus ensuring the smooth flow of the drainage channel.

[0029] A vertical guide pipe 3 is installed inside the pre-buried pipe 2. The vertical guide pipe 3 is a 20cm diameter HDPE perforated corrugated pipe with numerous first permeable holes on its wall, and is wrapped with non-woven geotextile 42. The non-woven geotextile 42 can further filter fine particulate impurities in the water, prevent the first permeable holes from clogging, and extend the service life of the vertical guide pipe 3. A sand and gravel filter layer 21 is filled between the vertical guide pipe 3 and the inner wall of the pre-buried pipe 2. The filter layer 21 is backfilled and compacted in layers from bottom to top. Inclined permeable pipes 4 are installed at 2m intervals along the vertical direction. Each inclined permeable pipe 4 is drilled and installed at an angle of 8° to 15° with the horizontal plane to facilitate drainage. The inclined permeable pipe 4 uses an 80mm diameter PVC pipe with several second permeable holes 41 on its wall. These holes are 10mm in diameter, spaced 50mm apart, and arranged in four rows evenly on the top, bottom, left, and right sides of the pipe. The holes at the top are symmetrical to those at the bottom, and the holes on the left are symmetrical to those on the right, with the top and bottom rows alternating with the left and right rows. This permeation pattern ensures effective water intake from all directions while maintaining the structural strength of the pipe. The inclined permeable pipe 4 is wrapped with a non-woven geotextile 42, which covers at least all the second permeable holes 41, acting as a filter to prevent soil particles from entering the pipe with the water. The lower end of the inclined permeable pipe 4 extends approximately 5cm into the pre-buried pipe 2 through the impermeable geomembrane 22, and the end furthest from the pre-buried pipe 2 is sealed with a filter screen.

[0030] The drainage device 6 is located on the side of the retaining wall 1 closest to the road 7, and specifically includes a longitudinal water guide pipe 61, a transverse water guide pipe 62, and a drainage ditch 63. The longitudinal water guide pipe 61 is a 20cm diameter HDPE corrugated pipe, pre-embedded at the bottom of the retaining wall 5 and laid along the length of the road 7 to collect groundwater flowing from the pre-embedded pipes 2. The lower end of the vertical water guide pipe 3 is connected to the longitudinal water guide pipe 61 via a tee joint, realizing the vertical-to-lateral collection of water flow. Multiple transverse water guide pipes 62 are installed every 5m along the road 7, also using 20cm diameter HDPE corrugated pipes. One end is connected to the longitudinal water guide pipe 61 via a tee joint, and the other end is introduced into the drainage ditch 63 located at the edge of the road 7. The drainage ditch 63 is a ditch excavated along the edge of the road 7 to collect and drain rainwater from the roadbed and groundwater behind the wall. The entire drainage path is fully enclosed from the back of the wall to the side ditch, which completely avoids the landscape pollution and slippery road surface caused by groundwater leakage, ensures pedestrian safety, and reduces the workload of subsequent wall cleaning and maintenance.

[0031] The method for constructing this concealed wall-mounted drainage structure is as follows: First, the retaining wall main body 1 is constructed. The piles of the retaining wall main body 1 include plain concrete piles 11 and reinforced concrete piles 12. The plain concrete piles 11 are constructed first, followed by the reinforced concrete piles 12. When pouring the plain concrete piles 11, vertical pre-embedded pipes 2 are accurately pre-embedded on the side of the pile body closest to the road 7, and the embedment position and verticality of the pre-embedded pipes 2 are strictly controlled so that their lower ends reach a depth of about 50cm below the designed road surface. Simultaneously, the capping beam 8 at the top of the retaining wall main body 1 is constructed, and two pipes are pre-embedded at the positions corresponding to the pre-embedded pipes 2 on the capping beam 8, forming a vertically connected inspection well 81.

[0032] After the concrete of the retaining wall main body 1 reaches the design strength, the soil in front of the wall is excavated in layers to the design elevation of road 7. Then, the accurate location of the embedded pipe 2 is measured and determined, and a vertical through-slot 23 is cut along the side of the embedded pipe 2 facing road 7 using a cutting machine. Inside the embedded pipe 2, multiple upward-sloping installation holes are drilled at intervals from the through-slot 23 towards the retaining wall main body 1 away from road 7 using a horizontal drilling rig. The installation holes are spaced two meters apart, with a hole diameter of 11 cm, and are arranged vertically. An inclined permeable pipe 4 is installed in each installation hole. During installation, the gap between the drilled hole and the inclined permeable pipe 4 is plugged with clay at the inner end of the pipe. A filter screen is wrapped around the end of the inclined permeable pipe to prevent blockage.

[0033] Next, the vertical water guide pipe 3, pre-wrapped with non-woven geotextile 42, is inserted into the pre-buried pipe 2, with a reserved connection length at the lower end. Wrapping the outside of the vertical water guide pipe 3 with non-woven geotextile 42 further prevents pipe blockage. Then, the sand and gravel filter layer 21 is gradually backfilled from bottom to top between the vertical water guide pipe 3 and the pre-buried pipe 2, with gentle vibration during backfilling to ensure compaction and prevent groundwater from bringing in sediment and blocking the pipe. At the same time, an impermeable geomembrane 22 is pasted across the entire cross-section of the opening of the vertical channel 23 to prevent cement slurry from entering the filter layer 21 and causing blockage when the reinforced concrete baffle 5 is poured later.

[0034] After the filter layer 21 is completed, the reinforcement of the baffle 5 is tied and the concrete is poured. A longitudinal water guide pipe 61 is pre-embedded at the bottom of the baffle 5 along the direction of road 7, and the lower end of the vertical water guide pipe 3 is connected to the longitudinal water guide pipe 61 via a tee joint. Simultaneously, transverse water guide pipes 62 are connected to the sides of the longitudinal water guide pipe 61 at 5m intervals. Finally, a drainage ditch 63 is excavated at the edge of the road at the design elevation, and the other end of the transverse water guide pipe 62 is introduced into the drainage ditch 63.

[0035] At this point, the entire concealed wall-back drainage structure is completed. Groundwater is collected by the inclined permeable pipe 4 and introduced into the pre-embedded pipe 2. After being filtered by the filter layer 21, it enters the vertical guide pipe 3, flows downward into the longitudinal guide pipe 61 at the bottom of the baffle 5, and then flows into the drainage ditch 63 through the horizontal guide pipe 62. The entire process is without exposure or overflow, achieving the goal of concealed and clean drainage.

[0036] Example 2 like Figures 12-13 The main difference between this embodiment and Embodiment 1 is that a pipe fitting is pre-embedded in the crown beam 8 at the position corresponding to the pre-embedded pipe 2, thereby forming a maintenance well 81 connected to the pre-embedded pipe 2. A well cover 82 is installed on the top of the maintenance well 81, and the upper end of the vertical guide pipe 3 extends upward and into the interior of the maintenance well 81. Before backfilling the filter layer 21, a support is installed on the outside of the vertical guide pipe 3 to support the filter layer 21. When the vertical guide pipe 3 becomes blocked or ages, it can be directly pulled out from the maintenance well 81. After the vertical guide pipe 3 is pulled out, the support supports the filter layer 21 to prevent it from collapsing. This preserves the installation hole of the vertical guide pipe 3 after it is pulled out, allowing the new vertical guide pipe 3 to be installed normally. At the same time, the support reduces the lateral squeezing force of the filter layer 21 on the vertical guide pipe 3, making it easy to remove and install the vertical guide pipe 3, greatly facilitating later maintenance. The inspection well 81 facilitates the regular inspection and replacement of the vertical guide pipe 3, ensuring drainage effectiveness and increasing the service life of the drainage system.

[0037] The above description is merely a preferred embodiment of the invention, but the scope of protection of the invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the invention should be included within the scope of protection of the invention.

Claims

1. A concealed drainage structure behind a pile-slab retaining wall, characterized in that, include: The retaining wall main body, embedded pipes, inclined permeable pipes, vertical guide pipes, drainage devices, filter layer and baffles; The pre-embedded pipe is vertically installed inside the main body of the retaining wall; The inclined permeable pipe is inserted into the soil at an angle, and the lower end of the inclined permeable pipe is connected to the pre-buried pipe. The vertical water guide pipe is installed inside the pre-embedded pipe, and a plurality of first water permeable holes are opened on the vertical water guide pipe. The reverse filter layer is installed between the pre-embedded pipe and the vertical water guide pipe. The baffle is installed on the side of the retaining wall body closest to the road; The drainage device is located on the side of the retaining wall body closest to the road, and the lower end of the vertical guide pipe is connected to the drainage device.

2. The concealed drainage structure behind a pile-slab retaining wall according to claim 1, characterized in that: The pre-embedded pipe is installed on the side of the retaining wall body closest to the road. A through groove is opened on the side of the retaining wall body, the through groove is connected to the inside of the pre-embedded pipe, the through groove is facing the road, the width of the through groove is greater than the diameter of the vertical water guide pipe, and an impermeable geomembrane is installed at the opening of the through groove.

3. The concealed drainage structure behind the pile-slab retaining wall according to claim 2, characterized in that: The retaining wall body includes reinforced concrete piles and plain concrete piles, which are alternately arranged, and the pre-embedded pipe is set inside the plain concrete pile; The embedded pipe is a corrugated pipe, and the embedded pipe extends downward to 40-60cm below the road surface; The vertical water guide pipe is wrapped with non-woven geotextile.

4. The concealed drainage structure behind the pile-slab retaining wall according to claim 1, characterized in that: The angle between the inclined permeable pipe and the horizontal plane is 8°~15°.

5. The concealed drainage structure behind the pile-slab retaining wall according to claim 1, characterized in that: The inclined permeable pipe is provided with several second permeable holes, arranged in four rows at the top, bottom, left, and right positions of the pipe. The second permeable holes at the top and bottom positions are symmetrically arranged, as are the second permeable holes at the left and right positions. The second permeable holes at the top and bottom positions and the second permeable holes at the left and right positions are staggered. The inclined permeable pipe is wrapped with non-woven geotextile, which at least covers the second permeable holes. The lower end of the inclined permeable pipe extends 3-8 cm into the pre-buried pipe.

6. The concealed back wall drainage structure of the pile-slab retaining wall according to claim 1, characterized in that: The drainage device includes a longitudinal water guide pipe, a transverse water guide pipe, and a drainage ditch; the drainage ditch is located at the edge of the road and close to the main body of the retaining wall; the longitudinal water guide pipe is arranged along the length of the drainage ditch; the vertical water guide pipe is connected to the longitudinal water guide pipe; the transverse water guide pipe is arranged at intervals along the length of the longitudinal water guide pipe; one end of the transverse water guide pipe is connected to the longitudinal water guide pipe, and the other end is connected to the drainage ditch.

7. The concealed back wall drainage structure of the pile-slab retaining wall according to claim 1, characterized in that: It also includes a capping beam set on the top of the main body of the retaining wall, and a maintenance well is provided in the capping beam. The position of the maintenance well corresponds to the position of the pre-embedded pipe, and the maintenance well is connected to the pre-embedded pipe.

8. The concealed back wall drainage structure of the pile-slab retaining wall according to claim 7, characterized in that: A support is also provided between the vertical water guide pipe and the reverse filter layer, and the support is used to support the reverse filter layer.

9. A construction method for a concealed back-wall drainage structure of a pile-slab retaining wall, used to manufacture the concealed back-wall drainage structure of the pile-slab retaining wall as described in any one of claims 1-8, characterized in that, Includes the following steps: S1, Construction of the main body of the retaining wall and its top capping beam; Pre-embed vertical pipes on the side of the retaining wall closest to the road; S2, After the main body of the retaining wall reaches the design strength, the soil is excavated in layers to the road design elevation; S3, Determine the location of the embedded pipe and cut a through groove along the side of the embedded pipe; S4. Multiple installation holes are drilled at intervals inside the pre-embedded pipe. The installation holes are opened in the direction away from the road from the main body of the retaining wall, and the installation holes are set in an upward direction at an angle. Multiple installation holes are set in the vertical direction, and an inclined permeable pipe is installed in the installation hole. S5, the vertical water guide pipe wrapped with non-woven geotextile is placed into the pre-buried pipe. After the vertical water guide pipe is buried, the filter layer is backfilled from bottom to top, and at the same time, the impermeable geomembrane is pasted at the opening of the through groove. S6, construct the retaining wall baffle, and construct a drainage device at the bottom of the baffle so that the lower end of the vertical guide pipe is connected to the drainage device.

10. A construction method for a concealed back wall drainage structure of a pile-slab retaining wall according to claim 9, characterized in that: In step S1, the main body of the retaining wall includes reinforced concrete piles and plain concrete piles, which are alternately installed. The plain concrete piles are constructed first, followed by the reinforced concrete piles. The embedded pipe is installed inside the plain concrete piles and extends downward to 40-60cm below the road surface.

11. The construction method of a concealed back wall drainage structure for a pile-slab retaining wall according to claim 9, characterized in that: In step S4, several inclined permeable pipes are arranged at intervals along the vertical direction, with an angle of 8° to 15° with the horizontal plane, and the lower end of the inclined permeable pipe extends into the pre-buried pipe by 3 to 8 cm.

12. The construction method of a concealed back wall drainage structure for a pile-slab retaining wall according to claim 9, characterized in that: In step S5, the impermeable geomembrane is made of HDPE membrane and is vertically arranged along the through groove.

13. The construction method of a concealed back wall drainage structure for a pile-slab retaining wall according to claim 9, characterized in that: In step S6, the construction drainage device specifically includes: pre-burying a longitudinal water guide pipe at the bottom of the baffle along the road direction, connecting the lower end of the vertical water guide pipe to the longitudinal water guide pipe; setting several transverse water guide pipes at intervals along the length of the longitudinal water guide pipe, connecting one end of the transverse water guide pipe to the longitudinal water guide pipe; excavating a drainage ditch at the edge of the road, and introducing the other end of the transverse water guide pipe into the drainage ditch.

14. The construction method of a concealed back wall drainage structure for a pile-slab retaining wall according to claim 9, characterized in that: In step S1, during the construction of the capping beam, pipe fittings are pre-embedded in the capping beam at the positions corresponding to the pre-embedded pipes, forming an inspection well that communicates with the pre-embedded pipes.

15. A construction method for a concealed back wall drainage structure of a pile-slab retaining wall according to claim 9, characterized in that: In step S5, before backfilling the filter layer, a support needs to be installed outside the vertical guide pipe. The support is used to support the filter layer.

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