Reinforced earth wall seismic reinforcement structure

Abstract

To improve earthquake resistance of a reinforcing earth wall by suppressing a wall face structure from tilting forward or collapsing in an earthquake by aseismatically reinforcing an upper layer of the reinforcing earth wall using a simple method.SOLUTION: Cast-in-place type horizontal concrete 50 is arranged across a plurality of wall face materials 31 arranged in a row at the uppermost stage of a wall face structure 30. A part of a top end brace material 51 is connected to the horizontal concrete 50. The top end brace material 51 is embedded in an embankment layer 21a so that resistant moment against earth pressure acting on the horizontal concrete 50 and the wall face material 31 located at the uppermost and an inertial force acting during an earthquake becomes large.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a seismic reinforcement structure for a reinforced earth wall that effectively suppresses displacement of the upper part of the reinforced earth wall.

Background Art

[0002] Referring to FIG. 8 and explaining, a conventional reinforced earth wall includes an embankment structure a and a wall structure b provided on the front surface of the embankment structure a. The wall structure b is composed of a plurality of wall materials c, and is structured to be connected between the embankment structure a and each wall material c by a connecting restraint material d (Patent Documents 1 to 5).

[0003] The wall material c is made of a concrete panel or block, etc., and the connecting restraint material d is made of a material such as a geotextile belt or strip steel material. Also, a cap concrete e is installed on the topmost part of the wall structure b.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0005] The conventional reinforced earth wall has the following problems. <1> During an earthquake, not only is the acceleration at the top end of the wall structure b amplified, but also the overturning moment of the wall structure e becomes larger towards the upper part. Therefore, the wall structure b is prone to collapsing as a whole, or the wall material c located above it may become displaced. <2> Traditionally, no specific seismic countermeasures have been taken for the concrete caps (e). Therefore, during an earthquake, the cap concrete e is prone to tipping forward together with the wall material c. <3> In sites where the longitudinal slope of wall structure b is the same as the slope of the embankment slope, the cap concrete e becomes locally higher, and the resistance moment of the connecting bracing member d decreases. As a result, when earth pressure is applied to the back of the cap concrete e, the stability against overturning becomes insufficient. Therefore, during an earthquake, only the cap concrete e is prone to displacement. <4> When repairing the wall structure b that has fallen forward, there are absolutely no elements that can be used to pull the wall structure b back to its original, correct position. Therefore, it is necessary to remove the wall structure b that has fallen forward and then reassemble it, requiring a lot of time and effort to repair the wall structure b that has fallen forward. <5> With large-scale earthquakes predicted to occur in the future, there is a need for proposals for technologies that can seismically reinforce existing reinforced earth walls using simple methods.

[0006] The present invention has been made in view of the above points, and its objective is to provide the following seismic reinforcement structure for reinforced earth walls. <1> To improve the seismic resistance of reinforced earth walls by seismically reinforcing the upper layer of the reinforced earth wall using a simple method, thereby suppressing the forward tilting or collapse of the wall structure during an earthquake. <2> If a cap concrete is installed at the top of the wall structure, the displacement and fall of the cap concrete should be suppressed. <3> To enable efficient repair work on wall structures that have fallen forward. <4> The ability to easily perform seismic reinforcement work on existing reinforced earth walls. [Means for solving the problem]

[0007] The present invention relates to an embankment structure and a wall structure formed by stacking multiple wall materials on the front side of the embankment structure. The cap concrete installed at the top of the aforementioned wall structure, and The embankment structure is equipped with connecting bracing members that receive reaction force and support the wall material. Existing A seismic reinforcement structure for a reinforced earth wall, wherein cast-in-place horizontal concrete is arranged across multiple wall materials lined up on the uppermost level of the wall structure, The aforementioned horizontal concrete integrally encloses the coping concrete. A portion of the top bracing member is connected to the horizontal concrete structure, and the top bracing member is embedded in the embankment structure and supported in such a way that the moment of resistance against the earth pressure acting on the horizontal concrete structure and the wall material located at the top of the wall structure, as well as the inertial force during an earthquake, is increased. In another embodiment of the present invention, the lower part of the horizontal concrete is integrated with a plurality of wall materials arranged in a row at the top of the wall structure. In another embodiment of the present invention, a portion of the top bracing member is anchored and connected to a portion of the horizontal concrete frame. In another embodiment of the present invention, a hollow box-shaped model may be embedded in the horizontal concrete frame, and a top bracing member may be inserted through the box-shaped model and the top bracing member may be anchored to and connected to the horizontal concrete frame. 。 Book In other embodiments of the invention, the reinforced earth wall may be an existing reinforced earth wall or a newly constructed reinforced earth wall. In another embodiment of the present invention, the reinforced earth wall may be a reinforced earth wall comprising an embankment structure reinforced with an embankment reinforcing material, a wall surface structure provided on the front side of the embankment structure, and an intermediate layer interposed between the embankment structure and the wall surface structure. [Effects of the Invention]

[0008] The present invention provides at least one of the following effects. <1> By simply placing cast-in-place horizontal concrete across multiple wall materials arranged in a row at the top of the wall structure, and embedding top bracing members connected to the horizontal concrete into the embankment structure, the upper part of the reinforced earth wall can be seismically reinforced. <2>Since it is possible to suppress the forward collapse and collapse of the wall structure during an earthquake, the seismic resistance of the reinforced earth wall can be significantly enhanced, enabling the reinforcement and restoration of the reinforced earth wall. <3>If a cap concrete is provided at the top of the wall structure, the displacement and fall of the cap concrete can be effectively suppressed. <4>For the reinforced earth wall, only the construction work of the in-situ cast horizontal concrete and the work of embedding the top edge retaining material connected to the horizontal concrete into the embankment structure are required. Therefore, seismic reinforcement work can be easily and economically carried out on existing reinforced earth walls. <5>Since the weight of the horizontal concrete helps to increase the connection force between the upper and lower wall materials provided in multiple stages, the suppression effect of the forward collapse and collapse of the wall materials located in multiple upper stages of the wall structure during an earthquake is significantly improved. <6>As a connecting means between the horizontal concrete and the top edge retaining material, a part of the top edge retaining material is directly connected to the horizontal concrete without using a metal connecting fitting. Therefore, the connection between the horizontal concrete and the top edge retaining material can be maintained over a long period. <7>Even if the upper wall structure collapses forward due to the influence of a huge earthquake or the like, it is possible to use the top edge retaining material connected to the horizontal concrete as a clue to pull back the collapsed wall structure to its original normal position. Therefore, the repair work of the collapsed wall structure can be efficiently carried out.

Brief Description of the Drawings

[0009] [Figure 1] Perspective view near the top edge of the reinforced earth wall with a part broken [Figure 2] Explanation diagram of the reinforced earth wall assumed by the present invention, where (A) is a longitudinal sectional view of the reinforced earth wall and (B) is a perspective view of the wall material [Figure 3] Explanation diagram of the seismic reinforcement work of the reinforced earth wall, showing the explanation diagram until the formwork is installed at the upper part of the wall structure [Figure 4] Explanation diagram of the seismic reinforcement work of the reinforced earth wall, where (A) is a plan view of FIG. 3 and (B) is a perspective view of the boxed-out model [Figure 5]This is an explanatory diagram for seismic reinforcement work on reinforced earth walls, where (A) is an explanatory diagram up to the point of pouring concrete into the formwork, and (B) is an explanatory diagram up to the point of connecting the top bracing member to the horizontal concrete structure. [Figure 6] Vertical cross-section of a reinforced earth wall after seismic reinforcement work is complete. [Figure 7] This is an explanatory diagram of Example 3 using a disposable formwork, where (A) is an explanatory diagram of the form applied to an existing reinforced earth wall, and (B) is an explanatory diagram of the form applied to a newly constructed reinforced earth wall. [Figure 8] Conventional reinforced earth wall model diagram [Modes for carrying out the invention]

[0010] [Example 1] <1> Reinforced earth wall Figure 2(A) shows the reinforced earth wall 10 that is the premise of the present invention. This example describes the case where the reinforced earth wall 10 is an existing reinforced earth wall.

[0011] The reinforced earth wall 10 comprises at least an embankment structure 20 and a wall surface structure 30 provided on the front side of the embankment structure 20. If necessary, an intermediate layer 25 made of single-sized crushed stone or the like may be interposed between the embankment structure 20 and the wall structure 30.

[0012] <2> Embankment structure The embankment structure 20 is a soil mass structure constructed by compacting soil and sand that were extruded in layers. In this example, a sheet-like embankment reinforcement material 22 is interposed between embankment layers 21 formed in layers on the back side of the wall structure 30, and the front surface of the embankment layers 21 is wrapped with the embankment reinforcement material 22. However, the front surface of the embankment layers 21 may also be supported by a formwork made of expanded metal with a strip of mesh bent into an L shape, or a soil mass structure may be constructed by compacting embankment material on the back side of the wall structure 30 without using the embankment reinforcement material 22. The embankment reinforcement material 22 includes geogrids, geotextiles, etc.

[0013] <3> Wall structure The wall structure 30 consists of multiple wall materials 31. In this example, we describe a configuration in which a cap concrete 35 is placed on top of the uppermost wall material 31, but this method can also be applied to configurations in which the cap concrete 35 is not placed.

[0014] <3.1> Wall materials The wall material 31 consists of concrete panels or blocks. To describe the block-type wall material 31 illustrated in Figure 2(B), the wall material 31 is integrally formed with a plate-shaped panel portion 32 and one or more protruding portions 33 that project backward from the back surface of the panel portion 32. The protruding portion 33 has an insertion hole 33a through which the connecting bracing member 40 can be inserted.

[0015] <3.2> Coping concrete The existing coping concrete 35 is made of cast-in-place concrete or precast concrete. The existing cap concrete 35 is placed across the top surface of multiple wall panels 31 arranged in parallel at the top level, and is not connected by any bracing or other means.

[0016] <4> Connecting brace The connecting brace member 40 is a belt-shaped, string-shaped, or rod-shaped tensile connecting member that connects the embankment structure 20 to the back surface of the wall material 31.

[0017] In this example, we will describe the case where the connecting brace 40 is a belt made of fiber, but the connecting brace 40 also includes strip steel materials called skin plates or steel bars. The connecting bracing member 40 is inserted through the insertion hole 33a of the protruding portion 33 of the wall material 31 and folded back, with both folded ends embedded inside the embankment layer 21.

[0018] <5> Middle class The intermediate layer 25 is a granular material such as single-sized crushed stone filled between the embankment structure 20 and the wall structure 30. The intermediate layer 25 functions as a drainage layer and a buffer layer. The intermediate layer 25 is not essential. The above are the components of the existing reinforced earth wall 10, and the following elements are materials that reinforce the reinforced earth wall 10 against earthquakes.

[0019] <6> Horizontal concrete The horizontal concrete 50 is a cast-in-place concrete horizontal member that is continuously and integrally added to the top of the wall structure 30 along the longitudinal direction of the wall structure 30 (Figure 1). The horizontal concrete 50 functions as a member that integrally connects the adjacent wall panels 31 arranged in the uppermost row.

[0020] <7> Top bracing The top bracing member 51 is a tensile connecting member that obtains a reaction force from the embankment layer 21a on the back side 50a of the horizontal concrete 50 and restrains the displacement of the horizontal concrete 50. The top bracing member 51 is partially connected to the horizontal concrete structure 50, and the majority of the bracing member is embedded in the embankment layer 21a on the back side. The total length of the top bracing member 51 can be appropriately selected considering the bearing capacity of the horizontal concrete 50, etc.

[0021] For example, a flexible, strip-shaped or cord-shaped tension member can be used as the top bracing member 51.

[0022] In addition to the method of connecting the top bracing member 51 to the horizontal concrete 50 by using a box-shaped model 45 embedded in the structure of the horizontal concrete 50 to anchor and connect the top bracing member 51, as in this example, it is also possible to directly embed one end of the top bracing member 51 into the structure of the horizontal concrete 50 for connection.

[0023] Another possible means of connecting the weight retainer 51 is to use a metal connecting fitting (for example, a combination of an insert and an eyebolt). If a metal connecting fitting is used to connect the top bracing member 51 to the horizontal concrete 50, the connecting fitting will corrode, causing the top bracing member 51 to lose its support function. In this invention, in order to avoid the problem of corrosion of such connecting fittings, a portion of the top bracing member 51 is directly connected to the horizontal concrete 50.

[0024] <8> boxed model This example describes a configuration using a box-type model 45 that is permanently embedded. Refer to Figure 4(B) for explanation. The box-shaped model 45 is a model for creating an insertion space for the top bracing member 51 in the horizontal concrete frame 50. In this example, the box-shaped model 45 is described as a molded resin product comprising a hollow curved body 46 bent into a U-shape or U-shape, and caps 48 capable of sealing the openings 47 at both ends of the curved body 46.

[0025] The curved shape of the curved body 51 is not limited to a U-shape or a U-shape, and may be bent into other shapes. The spacing between the openings at both ends of the curved body 51 can be appropriately selected to match the spacing between the top bracing members 51.

[0026] Other box-shaped models 45 may be models formed from materials that can be removed after molding the horizontal concrete 50.

[0027] [Methods for seismically reinforcing reinforced earth walls] This section describes seismic reinforcement methods for existing reinforced earth walls 10.

[0028] <1> Preparatory work (Figure 3) Remove a portion of the embankment so that the back of the top layer of concrete capping (35mm) is exposed. At this point, it is advisable to excavate the embankment until the top of the uppermost wall panel 31 is exposed.

[0029] <2> Formwork assembly (Figure 3) Next, formwork 41a and 41b for the horizontal concrete are assembled around the existing cap concrete 35. Formwork 41a and 41b are assembled at intervals and heights exceeding the width L and height H of the existing cap concrete 35.

[0030] In configurations where the cap concrete 35 is not placed on the wall material 31, formwork 41a and 41b for horizontal concrete are assembled around the uppermost wall material 31.

[0031] <3> Box-removed model kit (Figure 3) The box-shaped model 45 is set on the inner surface of the formwork 41b on the rear side, in accordance with the installation position of the top bracing member 51. At this point, the curved body 46 is turned sideways, and the cap 48 is brought into contact with the inner surface of the formwork 41b on the back side.

[0032] <4> Concrete pouring (Figure 5(A)) Next, concrete 50b is poured into the formwork 41a and 41b on which the box-shaped model 45 is placed to form the horizontal concrete 50. The horizontal concrete 50 embraces and integrates with the existing cap concrete 35 and the uppermost wall material 31.

[0033] Furthermore, in order to enhance the integrity of both concretes 35 and 40, it is advisable to install connecting reinforcement such as dowels or studs on the surface of the existing coping concrete 35.

[0034] <5> Connection of top bracing members (Figure 5(B)) Once concrete 50a has hardened, remove formwork 41a and 41b. The cap 48 of the box-shaped model 45 exposed on the back surface 50a of the horizontal concrete structure 50 is removed, and the curved body 46 is left inside the structure of the horizontal concrete structure 50. As shown in Figure 1, one end of the top bracing member 51 is inserted through the opening of the curved body 46 exposed on the back surface 50a of the horizontal concrete 50 and secured.

[0035] <6> Covering with soil (Figures 1, 6) The top bracing member 51, which is connected vertically to the horizontal concrete 50, is rotated 90 degrees and laid on the upper surface of the embankment layer 21 on the back side. After excavating soil and sand on the back side 50a of the horizontal concrete structure 50, the soil is compacted and the top bracing member 51 is embedded in the newly constructed upper embankment layer 21a. The thickness of the embankment layer 21a should be appropriately selected considering the bearing capacity of the top bracing members 51, etc.

[0036] [Regarding the seismic resistance of reinforced earth walls] Referring to Figure 6, the seismic resistance of the reinforced earth wall 10 with horizontal concrete 50 will be explained.

[0037] <1> Reinforced earth wall earthquake-resistant structure As described above, in this invention, a horizontal concrete 50 is constructed integrally with the wall material 31 located at the uppermost level of the wall structure 30, and a top bracing member 51 connected to the horizontal concrete 50 is embedded in the upper embankment layer 21a, thereby increasing the resistance moment against the earth pressure acting on the uppermost wall material 31 and the inertial force during an earthquake.

[0038] <2> Displacement suppression effect of coping concrete In this invention, the existing cap concrete 35 and the horizontal concrete 50 form an integrated structure, and the top bracing member 51 embedded in the embankment layer 21a is connected to the horizontal concrete 50. Therefore, even if seismic inertia forces and backfill earth pressure act on the horizontal concrete 50, including the existing cap concrete 35, it is supported by the resistance of the backfill layer 21a through the top bracing member 51.

[0039] Therefore, displacement and shearing motion of the uppermost cap concrete 35 and horizontal concrete 50 can be reliably suppressed. Therefore, the fall prevention performance of the cap concrete 35 and horizontal concrete 50 during an earthquake is enhanced.

[0040] <3> Displacement suppression effect of upper wall material During an earthquake or when backfill earth pressure is applied, a displacement force acts on the wall structure 30 in the front-to-back direction. In this invention, the existing cap concrete 35 and the horizontal concrete 50 form an integrated structure, and the horizontal concrete 50 is also integrated with the uppermost wall material 31.

[0041] Therefore, displacement (overturning) of the uppermost wall material 31 in the front-to-back direction can be reliably suppressed through the horizontal concrete 50 and top bracing material 51 supported by the embankment layer 21a. In other words, in this invention, by supporting the horizontal concrete 50 integrated with the uppermost wall material 31 through the top bracing member 51, the resistance moment against overturning of the wall material 31 is increased, and the effect of suppressing displacement (overturning) of the wall material 31 not only in the uppermost section but also in multiple sections is significantly enhanced. Therefore, the forward tilting and collapse of the multi-tiered wall material 31 located above the wall structure 30 during an earthquake can be effectively suppressed, and the seismic performance of the reinforced earth wall 10 can be significantly improved.

[0042] <4> Corrosion resistant Instead of using metal connecting fittings to connect the horizontal concrete 50 and the top bracing member 51, a portion of the top bracing member 51 is directly connected to the horizontal concrete 50. Therefore, the connection between the horizontal concrete 50 and the top bracing member 51 can be maintained over a long period of time.

[0043] [Example 2] In the previous example 1, we described a case in which seismic reinforcement was performed on an existing reinforced earth wall 10, but the present invention can also be applied to a newly constructed reinforced earth wall 10. When applied to a newly constructed reinforced earth wall 10, the cap concrete 35 is omitted, and the horizontal concrete 50 is directly constructed on the top of the wall structure 30.

[0044] In this example, the same seismic resistance effect as in Example 1 described above can be obtained.

[0045] [Example 3] In describing Example 3, the same parts as those in Example 1 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0046] Referring to Figure 7, we will now describe a configuration in which a cast-in-place horizontal concrete 50 is constructed at the top of the wall structure 30 using a precast concrete sacrificial formwork 41c instead of the formwork 41a.

[0047] <1> Form applied to existing reinforced earth walls Figure 7(A) shows an application to an existing reinforced earth wall 10, in which a sacrificial formwork 41c is erected on the front side of the upper surface of the cap concrete 35, and concrete is poured on the back side of the sacrificial formwork 41c to form a horizontal concrete 50 integrally with the sacrificial formwork 41c. It is desirable that the front of the sacrificial formwork 41c be flush with the front of the coping concrete 35, but it may also be erected at a position set back from the front of the coping concrete 35.

[0048] The horizontal concrete 50 shown in Figure 7(A) is thicker than the cap width L of the cap concrete 35, and the lower part of the rear side of the horizontal concrete 50 is formed so that it can be hooked onto the rear side of the cap concrete 35. The horizontal concrete structure 50 is integrated with multiple wall panels 31 located at the top level via the cap concrete 35.

[0049] <2> Form applied to newly constructed reinforced earth walls The horizontal concrete 50 shown in Figure 7(B) represents an application to a newly constructed reinforced earth wall 10. It shows a configuration in which a sacrificial formwork 41c is installed on the front side of the upper surface of multiple wall materials 3 arranged in a row at the top of the wall structure 30, and concrete is poured on the back side of the sacrificial formwork 41c to form the horizontal concrete 50 integrally with the sacrificial formwork 41c.

[0050] The horizontal concrete 50 shown in Figure 7(B) is integrated with multiple wall materials 31 located at the top. When integrating the horizontal concrete 50 with the uppermost wall material 31, by placing through-reinforcements 52 in the insertion holes 33a of the protruding portion 33 formed on the back of the wall material 31, and pouring concrete down to below the through-reinforcements 52, the horizontal concrete 50 can be firmly integrated with the uppermost wall material 31.

[0051] <3> The effect of this example As shown in Figure 5, in order to assemble the formwork 41a on the front side of the uppermost wall panel 31, it is necessary to assemble a separate work platform on the front side of the wall panel 31.

[0052] In this example, by placing the sacrificial formwork 41c on the top surface of the cap concrete 35 or the top surface of the uppermost wall material 31, it becomes unnecessary to set up and remove separate scaffolding on the front side of the wall material 31. Furthermore, since the sacrificial formwork 41c can be left in place after the concrete hardens, the construction work for the cast-in-place horizontal concrete 50 can be greatly simplified.

[0053] <4> Regarding the repair work after seismic reinforcement of reinforced earth walls For example, in the reinforced earth wall shown in Figure 6, which has undergone seismic reinforcement, we will consider the repair work in the event that the wall structure 30 collapses forward due to the effects of a massive earthquake or the like.

[0054] In this invention, even if the wall structure 30 tilts forward, the top bracing member 51 connected to the horizontal concrete 50 can be used as a guide to pull the tilted wall structure 30 back to its original correct position. In this case, by excavating the embankment layer 21 on the back side of the wall structure 30 to the required depth, it becomes possible to pull back the wall structure 30. Once the wall structure 30 has been pulled back, the embankment layer 21 is constructed by backfilling the back side of the wall structure 30 with soil. As explained above, the top bracing member 51 connected to the horizontal concrete 50 can be used as a guide to efficiently repair the wall structure 30 that has tilted forward. [Explanation of symbols]

[0055] 10. Reinforced earth wall 20. Embankment Structures 21. Embankment layer 22..Embankment reinforcement material 30..Wall structure 31. Wall materials 32.....Wall panel section 33. Protruding part of wall material 40... Connecting bracing 41a, 41b... formwork 45...Box model 46..Curved body of box-removed model 48... Cap for unboxed model 50... Horizontal concrete 51. Top surface bracing 52... Through-reinforcement

Claims

1. An existing reinforced earth wall seismic reinforcement structure comprising an embankment structure, a wall structure formed by stacking multiple wall materials on the front side of the embankment structure, a cap concrete installed at the top of the wall structure, and connecting bracing members that receive reaction force from the embankment structure and support the wall materials, Cast-in-place horizontal concrete is placed across multiple wall materials arranged in a row at the top of the wall structure, The aforementioned horizontal concrete integrally encloses the cap concrete, A portion of the top bracing member is connected to the aforementioned horizontal concrete, The top bracing member is embedded in the embankment structure and supported in such a way that the resistance moment against earth pressure and inertial forces during earthquakes acting on the uppermost wall material of the horizontal concrete and wall structure is increased. Seismic reinforcement structure using reinforced earth walls.

2. The seismic reinforcement structure for a reinforced earth wall according to claim 1, characterized in that the lower part of the horizontal concrete is integrated with a plurality of wall materials arranged in a row on the uppermost level of the wall structure.

3. The seismic reinforcement structure for a reinforced earth wall according to claim 1, characterized in that a portion of the top bracing material is anchored and connected to a portion of the horizontal concrete frame.

4. The seismic reinforcement structure for a reinforced earth wall according to claim 3, characterized in that a hollow box-shaped model is embedded in the horizontal concrete frame, and a top bracing member is inserted through the box-shaped model and the top bracing member is anchored to the horizontal concrete frame for connection.

5. The seismic reinforcement structure for a reinforced earth wall according to claim 1, characterized in that a sacrificial formwork is located on the front side of the upper surface of the cap concrete, and a cast-in-place horizontal concrete integrally formed with the sacrificial formwork is located on the back side of the sacrificial formwork.

6. The seismic reinforcement structure for a reinforced earth wall according to claim 1, characterized in that a sacrificial formwork is located on the front side of the upper surface of a plurality of wall materials arranged in a row at the top of the wall structure, and a cast-in-place horizontal concrete integral with the sacrificial formwork is located on the back side of the sacrificial formwork.

7. The seismic reinforcement structure for a reinforced earth wall according to claim 1, characterized in that the reinforced earth wall comprises an embankment structure reinforced with an embankment reinforcing material, a wall surface structure provided on the front side of the embankment structure, and an intermediate layer interposed between the embankment structure and the wall surface structure.

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