A retaining wall, an anti-clogging filter device, and a construction method

Abstract

This invention discloses a retaining wall, an anti-clogging filtration device, and a construction method, belonging to the field of hydraulic construction technology. The wall is buried under the soil layer on the slope behind the wall. A water collector is installed at the top of the wall structure, and an inner cavity communicating with the water collector is set inside the wall structure. A load-bearing wall is set on the front side, and several drainage holes are set on the load-bearing wall. Several drainage holes are connected to the inner cavity to pour groundwater into the inner cavity. A sedimentation tank is set inside the base. Both the drainage holes and the water collector drain water into the sedimentation tank, and the silt contained in the accumulated water will settle and accumulate in the sedimentation tank. On this basis, the top of the supporting member abuts against the load-bearing wall, and the bottom is set obliquely on the siphon member. The siphon member is fixedly set on the side of the sedimentation tank, and the sedimentation tank is connected to the water storage tank through the siphon member. The siphon member can guide the clear water in the upper part of the sedimentation tank into the water storage tank and discharge it into the municipal drainage main. The sludge in the lower part of the sedimentation tank is discharged from the inner cavity by a screw pump.

Description

Technical Field

[0001] This invention relates to the field of water conservancy construction technology, specifically to a retaining wall, an anti-clogging filtration device, and a construction method. Background Technology

[0002] A retaining wall is a structure that primarily bears earth pressure to prevent soil collapse and slippage. Traditional retaining wall structures often employ solid structures such as masonry or concrete, and incorporate drainage holes to lower the groundwater level behind the wall, thereby improving its stability. However, the drainage holes in traditional retaining walls are prone to blockage and are difficult to clear. During heavy rains, groundwater cannot be quickly drained from behind the wall, significantly impacting its stability and potentially leading to erosion or collapse, causing greater harm to life and property. Summary of the Invention

[0003] To address this issue, the present invention provides a retaining wall, an anti-clogging filtration device, and a construction method to solve the problem in the prior art where retaining walls are easily clogged and difficult to clear, leading to erosion or collapse.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] According to a first aspect of the invention,

[0006] The technical solution adopted in this invention is: to provide a retaining wall, comprising:

[0007] The wall structure has a water collector at the top and an inner cavity that communicates with the water collector. A load-bearing wall is provided on the front side, and a number of drainage holes are provided on the load-bearing wall, which communicate with the inner cavity.

[0008] The base and top are integrally formed with the wall structure, and a sedimentation tank is set inside. The sedimentation tank is located at the bottom of the inner cavity, and the drain hole and the water collector both drain water into the sedimentation tank.

[0009] The supporting component abuts against the load-bearing wall at the top and is obliquely mounted on the siphon component at the bottom. The siphon component is fixedly mounted on the side of the sedimentation tank, and the sedimentation tank is connected to the water storage tank through the siphon component.

[0010] Among them, several drainage holes are used to drain groundwater below the slope behind the wall, and water collectors are used to collect rainwater left on the slope behind the wall. All the water collected by both enters the sedimentation tank for settling. When the water level in the sedimentation tank is higher than the siphon component, the siphon component can guide the clear water in the upper part of the sedimentation tank into the storage tank and discharge it into the municipal drainage main. The sludge located in the lower part of the sedimentation tank is discharged from the inner cavity to the ground through a screw pump.

[0011] Furthermore, the supporting member is a suspended ladder arranged at an angle and serving a supporting function.

[0012] Furthermore, the base includes:

[0013] The wall base is integrally connected to the wall structure at the top and is provided with anti-slip keys at the bottom. A water storage tank is provided above the anti-slip keys.

[0014] The bottom of the wall toe is flush with the bottom of the wall base and is integrally connected to the front end of the wall base.

[0015] Furthermore, a triangular reinforcement structure is provided at the connection between the base and the wall structure. A water channel communicating with the sedimentation tank is provided at the top of the triangular reinforcement structure. The water channel is located directly below the water collector to divert the rainwater collected by the water collector.

[0016] Furthermore, an inspection door is sealed and installed at the exposed ground position on the front side of the wall structure.

[0017] Furthermore, a filter grate is provided at the upper end of the water collector;

[0018] Both the inner cavity and the inner wall of the sedimentation tank are provided with a waterproof layer.

[0019] Furthermore, a flow-stopping valve is provided on the siphon component;

[0020] The drainage hole is equipped with an anti-clogging device to filter mud and sand, and a telescopic clamp is installed inside the drainage hole to fix the anti-clogging device.

[0021] According to a second aspect of the invention,

[0022] The technical solution adopted in this invention is: to provide an anti-clogging filtration device, installed in the drainage hole of a retaining wall, comprising:

[0023] The housing has a rubber layer on the outside and a filter element inside, with through holes at both the front and rear ends communicating with the filter element.

[0024] The cone-shaped body has its tail end connected to the front end of the shell, and its side is provided with a water-permeable hole that communicates with the through hole.

[0025] Furthermore, the filter element comprises geotextile, medium-coarse sand, crushed stone, and gravel, which are arranged within the shell along the length of the shell.

[0026] According to a third aspect of the invention,

[0027] This invention discloses a construction method that applies the proposed retaining wall or anti-clogging filtration device, comprising the following steps:

[0028] 1. Excavate the foundation trench, erect formwork, tie reinforcing bars, pre-embed the connecting pipes and the pre-embedded parts required for installing the drainage control valve, pour concrete, and complete the pouring of the foundation and wall structure. At the same time, vertical reinforcing bars need to be reserved at the top of the foundation so that the water collector can be connected to the inner cavity as a whole.

[0029] 2. Erect formwork and tie steel bars. Pay attention to reserving drainage holes for installing anti-clogging filter devices, reserving and embedding holes and embedded parts for installing maintenance doors, and embedding embedded parts for installing telescopic clamps. Pour concrete to complete the pouring of the water collector. At the same time, vertical steel bars should be reserved at the top of the water collector to connect the wall structure with the water collector as a whole.

[0030] 3. Erect formwork, tie steel bars and pour concrete to complete the pouring of the wall structure; after the overall drainage retaining wall structure reaches the design strength, remove the formwork and lay geotextile from bottom to top on the back side of the structural wall.

[0031] 4. Construction personnel enter through the inspection door, inspect the shut-off valve, then control the telescopic clamp to keep it in the retracted state, install the anti-clogging filter device into the drain hole, then control the telescopic clamp to keep it in the extended state, support the anti-clogging filter device, and finally install the inspection door.

[0032] 5. Backfill the drainage retaining wall structure in layers on both sides and compact the soil until the backfill reaches the bottom of the road surface in front of the wall. Continue to backfill the soil behind the wall in layers and compact the soil.

[0033] VI. After all backfilling is completed, restore the road surface structure in front of the wall according to the original road surface structure design;

[0034] 7. Install a filter grate on the water collector to complete the construction of a drainage retaining wall structure with a replaceable anti-clogging device.

[0035] The beneficial effects of this invention are as follows:

[0036] Compared to existing technologies, this new method can quickly intercept runoff from the slope behind the wall and groundwater from the backfill soil by using a water collector at the top of the wall structure and an anti-clogging filtration device on the back side of the wall. The water is collected in a sedimentation tank, where it is discharged after settling for use. This achieves several advantages: first, it prevents runoff and groundwater from the slope behind the wall from being directly discharged onto the road surface, reducing the risk of road flooding; second, it quickly lowers the groundwater level behind the wall, improving the safety and stability of the retaining wall structure; third, the water accumulated in the water storage cavity increases the self-weight of the retaining wall structure, thereby improving its resistance to sliding and overturning; fourth, it transforms the harmful effects of groundwater on the retaining wall structure during heavy rain into beneficial effects; and fifth, the anti-clogging filtration device is replaceable, preventing blockage of the retaining wall's drainage structure. Attached Figure Description

[0037] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0038] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0039] Figure 1 A schematic diagram of the retaining wall structure provided by the present invention;

[0040] Figure 2 This is a schematic diagram of the wall structure and base provided by the present invention;

[0041] Figure 3 This is a schematic diagram of the siphon component structure provided by the present invention;

[0042] Figure 4 This is a schematic diagram of the installation of the anti-clogging filter device provided by the present invention;

[0043] Figure 5 This is a schematic diagram of the internal structure of the anti-clogging filter device provided by the present invention;

[0044] Figure 6 This is a top view of the anti-clogging filter device provided by the present invention;

[0045] In the diagram: 01 Back slope of the wall; 1 Wall structure; 2 Inner cavity; 3 Water collector; 4 Drainage hole; 5 Supporting component; 6 Water storage tank; 7 Siphon component; 8 Sedimentation tank; 9 Base; 91 Wall foundation; 92 Anti-slip key; 93 Wall toe; 10 Load-bearing wall surface; 11 Triangular reinforcement structure; 12 Waterway; 13 Inspection door; 14 Waterproof layer; 15 Filter grate; 16 Cut-off valve; 17 Telescopic clamp; 18 Screw pump; 19 Drainage control valve; a1 Rubber layer; a2 Filter element; a3 Shell; a4 Through hole; a5 Conical body; b1 Geotextile; b2 Medium and coarse sand; b3 Crushed stone; b4 Gravel. Detailed Implementation

[0046] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Please refer to the following: Figures 1 to 6 The retaining wall structure provided by the present invention will now be described.

[0048] The retaining wall structure disclosed in this embodiment of the invention is buried under the soil layer of the slope 01 behind the wall. A water collector 3 is installed at the top of the wall structure 1, and an inner cavity 2 communicating with the water collector 3 is provided inside the wall structure 1. A load-bearing wall surface 10 is provided on the front side, and a plurality of drainage holes 4 are provided on the load-bearing wall surface 10. The drainage holes 4 communicate with the inner cavity 2 to guide groundwater into a sedimentation tank 8. The bottom of the wall structure 1 is integrally formed with a base 9, and a sedimentation tank 8 is provided inside the base 9. The sedimentation tank 8 is located at the bottom of the inner cavity 2, and both the drainage holes 4 and the water collector 3 drain water into the sedimentation tank 8. The silt contained in the accumulated water will settle and accumulate in the sedimentation tank 8. Based on this, the top of the support member 5 abuts against the load-bearing wall 10, and the bottom is inclinedly set on the siphon member 7. The siphon member 7 is fixedly set on the side of the sedimentation tank 8, and the sedimentation tank 8 is connected to the storage tank 6 through the siphon member 7. Among them, several drainage holes 4 are used to drain the groundwater below the slope 01 behind the wall, and the water collector 3 is used to collect the rainwater left on the slope 01 behind the wall. All the water collected by both enters the sedimentation tank, and the silt contained in the water settles in the tank to prevent blockage of the water supply system. When the water level in the sedimentation tank 8 is higher than the siphon member 7, the siphon member 7 can guide the clear water in the upper part of the sedimentation tank 8 into the storage tank 6 and discharge it into the municipal drainage main. The sludge in the lower part of the sedimentation tank 8 is discharged from the inner cavity 2 by the screw pump 18.

[0049] In some embodiments, the support member 5 may be as follows: Figure 1 and Figure 2 The structure shown has a support member 5 that is an inclined suspended ladder that provides support. The drain hole 4 is equipped with a detachable anti-clogging filter device. During manual installation, the drain hole 4 can be accessed via the suspended ladder for replacement. Thus, the support member 5 serves both as a support and as a connection to the installation location.

[0050] In some embodiments, such as Figure 1The base 9 is integrally cast and includes a wall base 91, the top of which is integrally connected to the wall structure 1. An anti-slip key 92 is provided at the bottom, and a water storage tank 6 is located above the anti-slip key 92. Water accumulated in the water storage tank 6 is automatically discharged into the municipal drainage main through a siphon component 7 and a drainage control valve 19. Furthermore, the bottom of the wall toe 93 is flush with the bottom of the wall base 91 and integrally connected to the front end of the wall base 91, thereby improving the stability of the wall.

[0051] In this embodiment, as Figure 2 A triangular reinforcement structure 11 is provided at the connection between the base 9 and the wall structure 1. A water channel 12 connected to the sedimentation tank 8 is provided at the top of the triangular reinforcement structure 11. The water channel 12 is located directly below the water collector 3. This can effectively strengthen the structural strength of the wall structure 1 and also divert the rainwater collected by the water collector 3.

[0052] In one specific embodiment of this invention, an inspection door 13 is sealed and installed at the exposed ground position on the front side of the wall structure 1. Before maintenance, the maintenance shut-off valve 16 should be kept in the closed state. In an emergency, the inspection door 13 is closed to prevent large-scale leakage of water, while the shut-off valve 16 is in the open state to quickly drain the water in the water storage tank. Then, the inspection door 13 is opened, and maintenance personnel enter the inner cavity 2 to check whether the anti-clogging filter device is clogged. If clogged, a newly manufactured anti-clogging filter device is used to replace it. After the maintenance is completed, all valves are restored to normal operating conditions. It is strictly forbidden to enter the interior of the drainage retaining wall structure for maintenance in rainy weather.

[0053] In one specific embodiment of the present invention, a filter grate 15 is provided at the upper end of the water collector 3, an inverted filter body is laid at the bottom of the water collector 3, holes are reserved at the bottom of the water collector 3, and it is connected to the sedimentation tank 8 through a drain pipe. A waterproof layer 14 is provided on the inner wall of both the sedimentation tank 8 and the inner cavity 2.

[0054] In some embodiments, such as Figure 3 The siphon component 7 is equipped with a shut-off valve 16, and the drain hole 4 is equipped with an anti-clogging device for filtering silt and sand. The drain hole 4 is also equipped with a telescopic clamp 17 for fixing the anti-clogging device. One end of the siphon component 7 is connected to the sedimentation tank 8 and the other end is connected to the water storage tank 6. Structurally, the port of the siphon component 7 located in the sedimentation tank 8 is higher than the port of the water storage tank 6. Therefore, when the water level in the sedimentation tank 8 is higher than the height of the port of the siphon component 7 in the sedimentation tank 8, the clear water above the sedimentation tank 8 can be discharged into the water storage tank 6 by opening the shut-off valve 16.

[0055] Based on the same inventive concept, please refer to both. Figures 4 to 6 This invention discloses an anti-clogging filtration device, which is applied to the retaining wall mentioned above, including:

[0056] The shell a3 has a rubber layer a1 on the outside and a filter element a2 inside. Both the front and rear ends are provided with through holes a4 that communicate with the filter element a2.

[0057] Optionally, in this embodiment, a guide fluid is installed, the tail of which is connected to the front end of the housing a3, and a water-permeable hole communicating with the through hole a4 is provided on the side.

[0058] In one specific embodiment, the filter element a2 includes geotextile b1, medium-coarse sand b2, crushed stone b3 and gravel b4, which are arranged inside the shell a3 along the length of the shell a3.

[0059] Based on the same inventive concept, this invention discloses a construction method that applies the proposed retaining wall or anti-clogging filtration device, comprising the following steps:

[0060] 1. Excavate the foundation trench, erect formwork, tie steel bars, pre-embed the connecting pipe and the pre-embedded parts required for installing the drainage control valve 19, pour concrete, and complete the pouring of the foundation 9 and wall structure 1. At the same time, vertical steel bars need to be reserved at the top of the foundation 9 so that the water collector 3 can be connected to the inner cavity 2 as a whole.

[0061] 2. Erect formwork and tie steel bars. Note that you should reserve drainage holes 4 for installing anti-clogging filter devices, reserve and embed holes and embedded parts for installing maintenance doors 13, embed embedded parts for installing telescopic clamps 17, pour concrete, and complete the pouring of the water collector. At the same time, vertical steel bars should be reserved at the top of the water collector 3 to connect the wall structure 1 and the water collector 3 as a whole.

[0062] 3. Erect formwork, tie steel bars and pour concrete to complete the pouring of wall structure 1; after the overall drainage retaining wall structure reaches the design strength, remove the formwork and lay geotextile on the back side of the structural wall from bottom to top.

[0063] IV. Construction personnel enter through the inspection door 13, inspect the shut-off valve 16, then control the telescopic clamp 17 to make it retracted, install the anti-clogging filter device into the drain hole 4, then control the telescopic clamp 17 to make it extend, support the anti-clogging filter device, and finally install the inspection door 13.

[0064] 5. Backfill the drainage retaining wall structure in layers on both sides and compact the soil until the backfill reaches the bottom of the road surface in front of the wall. Continue to backfill the soil behind the wall in layers and compact the soil.

[0065] VI. After all backfilling is completed, restore the road surface structure in front of the wall according to the original road surface structure design;

[0066] 7. Install the filter grate 15 on the water collector to complete the construction of the drainage retaining wall structure with replaceable anti-clogging device.

[0067] The working principle of the retaining wall, anti-clogging filtration device, and construction method described in this invention is as follows:

[0068] During heavy rain, runoff from the slope 01 behind the drainage retaining wall structure converges at the toe of the slope, is collected by the collector 3, filtered by the inverted filter, and then quickly collected in the sedimentation tank 8 via the drainage pipe. Simultaneously, groundwater in the backfill soil behind the wall, raised by rainfall, is filtered through an anti-clogging filtration device and discharged into the sedimentation tank 8. After sedimentation, the sediment in the sedimentation tank 8 settles, and the clear water at the top enters the storage tank 6 through the siphon component 7, finally flowing into the municipal drainage main. During heavy rain, the interception... Valve 16 can automatically control the opening and closing degree of the valve according to the water level in the sedimentation tank 8, based on the principle of storing as much water as possible while meeting the bearing capacity of the foundation. During the non-rainy season, the shut-off valve 16 is kept open to lower the water level in the sedimentation tank 8, and the sludge deposited in the sedimentation tank 8 is discharged by the screw pump 18, thereby avoiding the problem of the water level in the sedimentation tank 8 rising due to excessive sedimentation. When the sedimentation tank 8 is insufficient in volume, the inspection door can be closed, and the entire inner cavity 2 can accommodate the accumulated water.

[0069] In this way, firstly, it can prevent runoff and groundwater from the slope 01 behind the wall from being directly discharged onto the road surface, thereby reducing the risk of road flooding; secondly, it can quickly lower the groundwater level behind the wall, improving the safety and stability of the retaining wall structure; thirdly, the water accumulated in the sedimentation tank 8 and the water storage tank 6 can increase the self-weight of the retaining wall structure, thereby improving the anti-sliding and anti-overturning capacity of the retaining wall structure; fourthly, it can convert the harmful effects of groundwater on the safety of the retaining wall structure during rainstorms into beneficial effects on the safety of the retaining wall structure; and fifthly, the anti-clogging and filtration device can be replaced at any time, thereby preventing the drainage structure of the retaining wall from becoming clogged.

[0070] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A construction method for a retaining wall, characterized in that, The retaining wall is buried under the soil layer on the slope (01) behind the wall, and the retaining wall includes: The wall structure (1) has a water collector (3) at the top and an inner cavity (2) connected to the water collector (3) inside. A load-bearing wall (10) is provided on the front side. Several drainage holes (4) are provided on the load-bearing wall (10) and the drainage holes (4) are connected to the inner cavity (2). The base (9) is integrally formed with the top of the wall structure (1) and has a sedimentation tank (8) inside. The sedimentation tank (8) is located at the bottom of the inner cavity (2), and the drain hole (4) and the water collector (3) both drain water into the sedimentation tank (8). The supporting member (5) abuts against the load-bearing wall (10) at the top and is obliquely set on the siphon member (7) at the bottom. The siphon member (7) is fixedly set on the side of the sedimentation tank (8). The sedimentation tank (8) is connected to the water storage tank (6) through the siphon member (7). A triangular reinforcement structure (11) is provided at the connection between the base (9) and the wall structure (1). A water channel (12) communicating with the sedimentation tank (8) is provided at the top of the triangular reinforcement structure (11). The water channel (12) is located directly below the water collector (3) to divert the rainwater collected by the water collector (3). Among them, several drainage holes (4) are used to drain the groundwater below the slope (01) behind the wall, and the water collector (3) is used to collect the rainwater flowing down the slope (01) behind the wall. All the water collected by both enters the sedimentation tank (8) to settle. When the water level in the sedimentation tank (8) is higher than the siphon component (7), the siphon component (7) can guide the clear water in the upper part of the sedimentation tank (8) into the water storage tank (6) and discharge it into the municipal drainage main. A drainage control valve (19) is set between the water storage tank (6) and the municipal drainage main. The mud located in the lower part of the sedimentation tank (8) is discharged from the inner cavity (2) by the screw pump (18). The wall structure (1) is sealed with an inspection door (13) at the exposed ground position on the rear side; a filter grate (15) is provided at the upper end of the water collector (3); and a waterproof layer (14) is provided on the inner wall of the inner cavity (2) and the sedimentation tank (8). A flow-stopping valve (16) is provided on the siphon component (7); an anti-clogging filtration device is provided in the drain hole (4) for filtering mud and sand, and a telescopic clamp (17) for fixing the anti-clogging filtration device is provided in the drain hole (4). The construction method for retaining walls includes the following steps:

1. Excavate the foundation trench, erect the formwork, tie the reinforcing bars, and pay attention to reserving the drainage hole (4) for installing the anti-clogging filter device, reserving the hole for the inspection door (13) and the embedded parts for installing the inspection door (13), and at the same time, reserving the expansion clamp (17), reserving the connecting pipe and the embedded parts required for installing the drainage control valve (19), pouring concrete, and completing the pouring of the foundation (9) and the wall structure (1). At the same time, the top of the wall structure (1) needs to reserve vertical reinforcing bars so that the water collector (3) can be connected to the inner cavity (2) as a whole.

2. Erect formwork, tie steel bars, pour concrete to complete the pouring of water collector (3). At the same time, vertical steel bars need to be reserved at the bottom of water collector (3) to strengthen the structural strength and make the wall structure (1) and water collector (3) connected as a whole.

3. After the overall retaining wall structure reaches the design strength, remove the formwork and lay geotextile on the back side of the wall structure (1) from bottom to top.

4. Construction personnel enter through the inspection door (13) hole, inspect the shut-off valve (16), then control the telescopic clamp (17) to make it retracted, install the anti-clogging filter device into the drain hole (4), then control the telescopic clamp (17) to make it extend, support the anti-clogging filter device, and finally install the inspection door (13).

5. Backfill the soil on both sides of the retaining wall structure in layers and compact it until the backfill in front of the wall reaches the bottom of the road surface. Continue to backfill the soil behind the wall in layers and compact it. VI. After all backfilling is completed, restore the road surface structure in front of the wall according to the original road surface structure design; 7. Install a filter grate (15) on the water collector (3) to complete the construction of a drainage retaining wall structure with a replaceable anti-clogging filter device.

2. The construction method for the retaining wall as described in claim 1, characterized in that, The supporting member (5) is a suspended ladder arranged at an angle and serving a supporting function.

3. The construction method for the retaining wall as described in claim 1, characterized in that, The base (9) includes: The wall base (91) is integrally connected to the wall structure (1) at the top and is provided with an anti-slip key (92) at the bottom. A water storage tank (6) is provided above the anti-slip key (92). The bottom of the wall toe (93) is flush with the bottom of the wall base (91) and is integrally connected to the front end of the wall base (91).

4. The construction method of the retaining wall as described in claim 1, characterized in that, The anti-clogging filter device includes: The housing (a3) ​​has a rubber layer (a1) on the outside and a filter element (a2) inside. Both the front and rear ends are provided with through holes (a4) that communicate with the filter element (a2). The cone-shaped body (a5) has its tail end connected to the front end of the shell, and its side is provided with a water-permeable hole that communicates with the through hole (a4).

5. The construction method for the retaining wall as described in claim 4, characterized in that, The filter element (a2) includes geotextile (b1), medium-coarse sand (b2), crushed stone (b3) and gravel (b4), which are arranged inside the shell (a3) ​​along the length of the shell (a3).

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