Reinforcement structure for masonry retaining wall and its construction method

Abstract

To provide a reinforcement structure for masonry retaining walls and its construction method, which inhibits flow-out of fillers and collapse of masonry retaining walls and at the same time realizes highly stable reinforcement effect.SOLUTION: This invention relates to a reinforcement structure for masonry retaining walls constructed by stacking a plurality of wedge stones placed adjacently to each other on the surface of a ground, comprising: holes drilled at locations on the aforesaid wedge stones or at boundaries between the aforesaid wedge stones; and a reinforcement member inserted from the aforesaid hole to a designated depth in a soil layer constituting the aforesaid ground. The aforesaid reinforcement member includes a hollow pipe material and a packer material surrounding the aforesaid pipe material. The aforesaid packer material has a resin material filled in it in the wedge stone region in the front side of the aforesaid ground with the aforesaid reinforcement material, while the aforesaid packer material having a hardener filled in it in the ground region in the rear side of the aforesaid ground with the aforesaid reinforcement material.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a reinforcement structure for a masonry retaining wall in which a soil layer is provided on the back surface of a filler stone or stone material via gravel or broken granite, or in which a soil layer is provided directly on the back surface of a filler stone or stone material, and a construction method thereof. [Background technology]

[0002] Stone retaining walls are known as structures that prevent the collapse of sloping ground surfaces. In these masonry retaining walls, rainwater is likely to flow into the gaps between the stones due to shaking caused by earthquakes, aging, and deterioration over time. For these reasons, there is a concern that the soil layer may become hollow from the back side of the masonry retaining wall to the inside, and that the earth pressure resistance of the ground may decrease. If the hollowing occurs inside and the earth pressure resistance decreases, the strength of the entire masonry retaining wall may decrease, leading to the risk of collapse.

[0003] Therefore, for example, Patent Document 1 discloses a method of reinforcing a masonry wall in which a reinforcing material is cast into the joints of gap stones in the masonry wall and grout material is filled around the reinforcing material to fix the reinforcing material to the sloping ground and restrain the gap stones arranged adjacent to the periphery of the joints. Also, for example, Patent Document 2 discloses a reinforcing method of a masonry wall in which a hardened layer of urethane foam is formed in the gaps in the backfill grit stone layer of the masonry wall to strengthen the connection of the masonry wall to the sloping ground. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2005-9207 A [Patent Document 2] Patent Publication No. 2022-69791 Summary of the Invention [Problem to be solved by the invention]

[0005] In general natural ground reinforcement soil, the gradient is small, so problems such as the grout flowing out of the reinforcement material after pouring the reinforcement material and injecting grout into the reinforcement material are unlikely to occur. On the other hand, in stone retaining walls, the infill stones are often piled up at a steep gradient, so when pouring the reinforcement material, the pouring angle is nearly horizontal.

[0006] The method of injecting and filling grout using the reinforcing material described in Patent Document 1 above has the problem that the grout material is likely to flow out due to the steep slope. Furthermore, pressurization of the grout may cause collapse in a masonry retaining wall that has become loose due to shaking caused by earthquakes, aging, deterioration over time, etc. Also, the method of forming a hardened layer of urethane foam described in Patent Document 2 above has the risk of not being able to obtain the required pull-out strength because the pull-out resistance between the urethane and the natural ground is low.

[0007] Therefore, the inventors have decided to realize a reinforcement structure for a stone retaining wall in which filler stones and the like are piled up at a steep slope, which prevents the outflow of filler material and the collapse of the stone retaining wall due to the pressure of the filler associated with reinforcement, and which provides a highly stable reinforcement effect by filling it with a filler material with high pull-out resistance.

[0008] In view of the above circumstances, the object of the present invention is to provide a reinforcement structure for a stone retaining wall and a construction method thereof that suppresses the outflow of filler material and the collapse of the stone retaining wall, and achieves a highly stable reinforcement effect. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, according to the present invention, there is provided a reinforcement structure for a masonry retaining wall in which a number of infill stones are piled adjacent to each other on the surface of the ground, the reinforcement structure comprising: a hole drilled on the infill stone or at the boundary between the infill stones; and a reinforcing member inserted through the hole to a predetermined depth in the soil layer constituting the ground, the reinforcing member including a hollow pipe material and a packer material surrounding the pipe material, the packer material being filled with a resin material in the infill stone area on the surface side of the ground including the reinforcing member, and the packer material being filled with a hardening material in the ground area on the back side of the ground including the reinforcing member.

[0010] The reinforcing member may be inserted into a hole drilled on the gap stone, and the pipe material may be fixed to the opening of the hole drilled on the gap stone.

[0011] The resin material may be urethane and the hardener may be grout.

[0012] According to another aspect of the present invention, there is provided a construction method for constructing a reinforcing structure of a stone retaining wall in which a number of infill stones are stacked adjacent to each other on the surface of the ground, the construction method comprising drilling holes on the infill stones or at the boundaries between the infill stones, and inserting reinforcing members through the holes to a predetermined depth in the soil layer that constitutes the ground, the reinforcing members including a hollow pipe material and a packer material surrounding the pipe material, filling the packer material with a resin material in the infill stone area on the surface side of the ground including the reinforcing member, and filling the packer material with a hardening material in the ground area on the back side of the ground including the reinforcing member. Effect of the Invention

[0013] According to the present invention, in reinforcing a masonry retaining wall, the outflow of filler and the collapse of the masonry retaining wall are suppressed, and a highly stable reinforcing effect is achieved. [Brief description of the drawings]

[0014] [Figure 1]FIG. 1 is a schematic explanatory diagram showing an example of the configuration of a stone retaining wall. [Diagram 2] FIG. 1 is a schematic diagram showing an example of a conventional method for reinforcing a masonry retaining wall. [Diagram 3] FIG. 1 is a schematic diagram showing an example of a conventional method for reinforcing a masonry retaining wall. [Figure 4] FIG. 1 is a schematic diagram showing an example of a conventional method for reinforcing a masonry retaining wall. [Diagram 5] 1 is a schematic explanatory diagram of a reinforcement structure of a stone retaining wall according to this embodiment. FIG. [Figure 6] 1 is a schematic explanatory diagram of a reinforcement structure of a stone retaining wall according to this embodiment. FIG. [Figure 7] 1 is a schematic explanatory diagram of a reinforcement structure of a stone retaining wall according to this embodiment. FIG. [Figure 8] FIG. 4 is a schematic explanatory diagram showing a configuration of a reinforcing member. [Figure 9] FIG. 2 is a schematic explanatory diagram showing the reinforcement structure in an actually constructed state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this specification and the drawings, components having substantially the same functional configurations are given the same reference numerals to avoid repeated explanations. Also, components and the like that overlap between the description of the conventional technology and the description of this embodiment may be given the same reference numerals to avoid repeated explanations.

[0016] <Outline of stone retaining wall structure> Fig. 1 is a schematic explanatory diagram showing an example of the configuration of a masonry retaining wall 1. As shown in Fig. 1, the masonry retaining wall 1 includes a soil layer 10, which is a sloping bedrock of natural ground, and gap stones 20 piled up on the surface (upper surface, sloping surface) of the soil layer 10 via broken granite stones 14 and gravel 15. That is, on the surface of the soil layer 10, a plurality of gap stones 20 are piled up vertically and horizontally so as to be adjacent to one another. The plurality of gap stones 20 may be provided without gaps, or may be provided so as to form gaps of a predetermined width at the boundaries between adjacent gap stones 20.

[0017] In addition, although FIG. 1 shows a configuration in which the broken granite stones 14 and gravel 15 are provided, the gap stones 20 may be directly piled up on the surface of the soil layer 10 without the broken granite stones 14 and gravel 15. The gap stones 20 may be configured, for example, to have a substantially square front surface, with each of the multiple gap stones 20 having substantially the same length toward the natural ground side and a substantially triangular vertical cross section. In addition, gap stones 20 having a rectangular cross section may be arranged so that one is arranged horizontally so that its longitudinal direction extends horizontally along the natural ground surface, and the other is arranged vertically so that its longitudinal direction extends toward the natural ground side, alternately adjacent to each other. In this specification, in order to simplify the illustration and description, the gap stones 20 may be illustrated simply as stones having a rectangular cross section.

[0018] <Problems with the prior art> 2 to 4 are schematic diagrams showing an example of a conventional method for reinforcing a masonry retaining wall 1. As one of the conventional techniques, as shown in Fig. 2, a technique is known in which, when reinforcing a masonry retaining wall 1, a space 32 into which a pipe material 30 can be inserted is drilled, and a hardening material such as grout material is injected into the space 32. In this case, if the masonry retaining wall 1 has a steep slope, there is a risk that the hardening material will flow out of the space 32 as shown in the figure.

[0019] Also, as shown in Fig. 3, a technique is known in which, when reinforcing a masonry retaining wall 1, packer materials 40 are provided so as to surround a pipe material 30, the pipe material 30 is inserted while surrounded by the packer materials 40, and a hardening material such as grout is pressurized and injected into the packer material 40. In this case, when a hardening material is pressurized and injected into the packer material 40, there is a risk that the gap stones 20 located nearby may be affected and collapse (see the arrow in the figure). This problem becomes particularly noticeable when the masonry retaining wall 1 becomes loose due to shaking caused by an earthquake, aging, deterioration over time, etc.

[0020] Also, as shown in Figure 4, a technique is known in which, when reinforcing a stone retaining wall 1, packer materials 40 are provided so as to surround a pipe material 30, the pipe material 30 is inserted while surrounded by the packer materials 40, and a resin material such as urethane is injected into the packer materials 40. In this case, the pull-out resistance of the resin material to the ground (soil layer 10) is low, and there is a risk that the necessary pull-out strength cannot be obtained, and a highly stable reinforcing effect cannot be obtained.

[0021] In view of these problems, the inventors have conducted extensive research into a reinforcement structure for a masonry retaining wall 1 that can prevent the outflow of filler (hardening material or resin material) used during reinforcement and the collapse of the masonry retaining wall, while also providing a highly stable reinforcement effect. Hereinafter, a reinforcement structure 50 for a masonry retaining wall according to this embodiment based on this research will be described with reference to the drawings.

[0022] <Reinforcement structure of stone retaining wall according to this embodiment> Figures 5 to 7 are schematic explanatory diagrams of a reinforcement structure 50 for a stone retaining wall according to this embodiment, with Figure 5 being a schematic plan view, Figure 6 being a schematic front view, and Figure 7 being a schematic side view. As shown in Figure 5, in the configuration according to this embodiment, a reinforcing member 60 is inserted into a soil layer 10 located on the back side (natural ground side) of the stone retaining wall 1. The reinforcing member 60 is inserted, for example, by drilling holes in the gap stones 20.

[0023] As shown in Figures 5 and 6, multiple contact stones 20 may be provided adjacent to each other, and the orientation of adjacent contact stones 20 may be different. That is, the contact stones 20 shown in the figure, which are approximately rectangular in shape, may be provided adjacent to each other in alternating rows of horizontally arranged stones with their longitudinal direction extending horizontally along the surface of the ground and vertically arranged stones with their longitudinal direction extending toward the ground.

[0024] As shown in Figures 6 and 7, at least some of the gap stones 20 have holes 55 drilled toward the natural ground. As shown in Figure 7, the holes 55 extend to a position deeper than the installation length of the gap stones 20, penetrate the gap stones 20, and extend to a predetermined depth of the soil layer 10. In this embodiment, the holes 55 are illustrated as being drilled into the gap stones 20, but the holes 55 may be formed at the boundary between adjacent gap stones 20.

[0025] As shown in FIG. 7, a reinforcing member 60 for reinforcing the reinforcement structure 50 of the masonry retaining wall is inserted into the hole 55. Here, as shown in the figure, a predetermined range of the area on the front side of the reinforcing member 60 and its periphery is defined as a natural ground area W1, and a predetermined range of the area on the natural ground side (back side) is defined as a natural ground area W2. The length (depth) of the natural ground area W1 may be, for example, approximately the same length as the longitudinal length L1 of the rectangular natural ground area 20. The length (depth) of the natural ground area W2 is determined according to the construction site. That is, the natural ground area W1 refers to the range including the natural ground area 20 (stone material) including gravel, broken granite, cavities, etc. on the back side of the natural ground area 20, and the natural ground area W2 refers to the range located deeper than the natural ground area W1 in the natural ground (soil layer 10).

[0026] In the reinforcing member 60, the resin material U1 is filled in the gap stone area W1, and the hardening material U2 is filled in the natural ground area W2. The resin material U1 may be, for example, urethane (urethane foaming agent), and the hardening material U2 may be, for example, cement-based materials such as cement milk. The pull-out resistance of the hardening material U2 against the soil layer 10 is preferably higher than that of the resin material U1. The pull-out resistance of the hardening material U2 against the soil layer 10 is generally preferably equal to or greater than the design load required for the reinforcing member 60. In contrast, the resin material U1 is filled in the back of the gap stone 20, the gaps between the gap stones 20, the gravel or sand on the back of the gap stone 20, or the hollow portion, and only needs to have a pull-out resistance sufficient to inhibit the movement of the gap stone 20, the gravel, or the sand, so that a load smaller than the design load required for the reinforcing member 60 is sufficient.

[0027] The reinforcing member 60 includes a hollow pipe material 30 and a packer material 40 surrounding the pipe material 30. The pipe material 30 may be, for example, a rock bolt, and the packer material 40 may be, for example, a bag-shaped fibrous material that is permeable to a liquid material. The detailed structure of the reinforcing member 60 will be described below with reference to FIG. 8.

[0028] <Structure of reinforcing member> FIG. 8 is a schematic explanatory diagram showing the configuration of the reinforcing member 60, and shows a schematic cross section of the reinforcing member 60 inserted into the hole 55 drilled in the gap stone 20. As shown in FIG. 8, the reinforcing member 60 includes a hollow pipe material 30 with both ends open, and a packer material 40 attached so as to surround the pipe material 30, and a cable tie 66 is attached to a predetermined position in the longitudinal direction. When the reinforcing member 60 is inserted into the hole 55, the natural ground side end 30a, which is one end of the pipe material 30, is not restrained, while the other end, the gap stone side end 30b, is fixed to the opening 55a of the hole 55 drilled in the gap stone 20. As an example of the fixing means, a spiral groove is formed on the peripheral surface of the pipe material 30, and the pipe material 30 is inserted into the hole 55 and screwed into the opening 55a using a nut member 68.

[0029] The opening 55a of the hole 55 formed in the gap stone 20 may have a two-stage drilling structure, and the opening diameter φ1 on the front side of the gap stone 20 may be different from the opening diameter φ2 on the back side of the gap stone 20. In the cross-sectional view shown in Figure 8, as an example of dimensions, the cross section of the gap stone 20 may be 200 mm x 200 mm, and the two-stage drilled hole diameters may be 90 mm and 65 mm.

[0030] As shown in the figure, in the reinforcing member 60, the area including the inside of the packer material 40 is divided into two by binding with a cable tie 66, the area close to the gap stone 20 is configured as the gap stone area W1, and the area close to the soil layer 10 is configured as the natural ground area W2. A hose 70 may be inserted into the gap stone area W1 from the opening 55a, and the resin material U1 is filled into the gap stone area W1 with this hose 70. Meanwhile, in the natural ground area W2, the hardening material U2 is filled from the opening of one end (natural ground side end 30a) of the pipe material 30. The gap stone area W1 and the natural ground area W2 are not connected by the binding with the cable tie 66, and the resin material U1 and the hardening material U2 are configured not to be mixed with each other.

[0031] <Reinforcement structure construction> Fig. 9 is a schematic explanatory diagram showing a state in which a reinforcement structure 50 of a masonry retaining wall according to this embodiment is actually constructed. As shown in Fig. 9, in the reinforcement structure 50, a resin material U1 is filled in a gap stone area W1 of the packer material 40 of the reinforcing member 60, and a hardening material U2 is filled in a natural ground area W2 of the packer material 40. The filled resin material U1 and hardening material U2 permeate and harden so as to seep out from the surface of the packer material 40 made of permeable fibrous material, and the reinforcement structure 50 is constructed.

[0032] An example of the construction flow is as follows. First, in a masonry retaining wall 1 including a plurality of gap stones 20 piled up on the surface (upper surface, inclined surface) of a soil layer 10 via broken granite stones 14 and gravel 15 (not shown in FIG. 9), holes are drilled in the gap stones 20 at predetermined positions. At that time, the holes may be drilled in two stages so that the reinforcing members 60 inserted in the drilled holes 55 do not protrude from the surface of the gap stones 20 (see FIG. 8).

[0033] Next, the reinforcing member 60 including the pipe material 62 and the packer material 40 attached so as to surround the pipe material 62 is inserted into the hole 55. At this time, the reinforcing member 60 is inserted in a state in which the two regions (the gap stone region W1 and the natural ground region W2) including the inside of the packer material 40 are separated by binding with a cable tie 66 (not shown in FIG. 9).

[0034] Next, the resin material U1 and the hardening material U2 are filled inside the packer material 40. The resin material U1 may be filled through a hose 70 (not shown in FIG. 9) inserted into the gap stone area W1. The hardening material U2 may be filled from the tip (natural ground side end 30a) of the pipe material 30 to the natural ground area W2. The filling completion condition differs depending on the nature of the natural ground (soil layer 10) to be worked on. As an example, the hardening material U2 may be filled by injecting until the filling pressure reaches 0.2 MPa, and the filling may be completed when the filling pressure reaches 0.2 MPa. However, depending on the work site, the filling pressure may not reach 0.2 MPa, in which case the filling may be completed by injecting the amount including the volume loss rate. It is preferable that the resin material U1 and the hardening material U2 are filled to the extent that the resin material U1 and the hardening material U2 seep out from the packer material 40 to the surroundings.

[0035] Next, the end portion on the surface side of the pipe material 30 (end portion 30b on the side of the contact stone) is fixed to the opening portion 55a of the hole portion 55. With the pipe material 30 inserted in the hole portion 55, it may be fixed by screwing it into the opening portion 55a using a nut member 68 (not shown in FIG. 9). At this time, a washer or other member not shown may be attached to perform the screwing. Then, the inside of the opening portion 55a is filled with a hardening material such as grout to close it, and the construction is completed. When closing the opening portion 55a, a closing member 59 may be attached (see FIG. 8).

[0036] In the reinforcement structure 50 for the masonry retaining wall 1 constructed as described above, the gap stone area W1 on the surface side of the reinforcing member 60 is filled with resin material U1, and the resin material U1 hardens in a state in which it permeates into the surrounding area as it seeps out from the packer material 40. Meanwhile, the natural ground area W2 on the natural ground side of the reinforcing member 60 is filled with hardening material U2, and the hardening material U2 hardens in a state in which it permeates into the surrounding area as it seeps out from the packer material 40. In this manner, the construction of the reinforcement structure 50 is completed.

[0037] <Action and effect> As described above, in the reinforcement structure 50 of the masonry retaining wall 1 according to this embodiment, the gap stone area W1 is filled with the resin material U1 as a filler, and the natural ground area W2 is filled with the hardening material U2 as a filler. On the surface side (the gap stone side) of the masonry retaining wall 1, the self-foaming resin material U1 such as urethane flows into the gaps between adjacent gap stones 20, ensuring reliable repair and reinforcement. Since the pressure associated with filling the resin material U1 is lower than the pressure when the hardening material U2 is used, the movement of the gap stones 20 associated with the pressurized filling of the filler is suppressed on the surface side of the masonry retaining wall 1 including the gap stone area W1, and the collapse of the masonry retaining wall 1 can be prevented.

[0038] Furthermore, on the back side (natural ground side) of the masonry retaining wall 1, a hardening material U2 such as grout having higher pull-out resistance permeates and hardens into the soil layer 10. By using the hardening material U2 having high pull-out resistance, a stable reinforcing effect by the filler can be obtained on the natural ground side of the masonry retaining wall 1 including the natural ground region W2.

[0039] Although an example of an embodiment of the present invention has been described above, the present invention is not limited to the illustrated embodiment. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention.

[0040] For example, in the above embodiment, the configuration of the reinforcing member 60 is illustrated and described as including the pipe material 30 having a hollow interior and the packer material 40 surrounding the periphery of the pipe material 30, but the present invention is not limited to this. For example, in addition to the above configuration, a PVC pipe or a steel pipe having holes may be disposed on the circumferential surface of the outer periphery of the pipe material 30, and the packer material 40 may be provided on the outside thereof. If the diameter of the pipe material 30 is small, there is a risk of the pipe material 30 being damaged due to the pressurized filling of the filler material (resin material U1, hardener material U2), so that a more stable construction of the reinforcing structure 50 can be realized by reinforcing it with a PVC pipe or a steel pipe. [Industrial Applicability]

[0041] The present invention can be applied to reinforcement structures and construction methods for stone retaining walls in which a soil layer is laid on the back surface of a retaining stone or stone material via gravel or broken granite, or in which a soil layer is laid directly on the back surface of a retaining stone or stone material. [Explanation of symbols]

[0042] 1... Stone retaining wall 10…soil layer 14…Broken granite 15…Gravel 20…Machinishi 30…Pipe material 32…Space 40…Packer material 50…Reinforcement structure 55...hole 60…Reinforcing member 66…Cable tie 68...Nut member 70…Hose W1: Interstitial stone area W2: Natural rock mass area U1: Resin material U2…Hardening material

Claims

1. A reinforcement structure for a masonry retaining wall in which a plurality of infill stones are piled up adjacent to each other on the surface of the ground, A hole portion drilled on the gap stone or at a boundary between the gap stones; a reinforcing member inserted through the hole to a predetermined depth of the soil layer constituting the natural ground, The reinforcing member includes a hollow pipe material and a packer material surrounding the pipe material, The packer material is filled with a resin material in a gap stone area on the surface side of the ground including the reinforcing member, A reinforcement structure for a masonry retaining wall, characterized in that the packer material is filled with hardening material in the ground area on the back side of the ground including the reinforcing member.

2. The reinforcing member is inserted into a hole drilled on the indentation stone, 2. The reinforcing structure for a masonry retaining wall according to claim 1, wherein the pipe material is fixed to an opening of a hole drilled in the retaining stone.

3. 3. The reinforcement structure for a masonry retaining wall according to claim 1 or 2, characterized in that the resin material is urethane and the hardening material is grout.

4. A construction method for constructing a reinforcement structure of a masonry retaining wall in which a plurality of mortar stones are piled up adjacent to each other on the surface of the ground, A hole is drilled on the gap stone or at the boundary between the gap stones, Inserting a reinforcing member through the hole to a predetermined depth of the soil layer constituting the natural ground; The reinforcing member includes a hollow pipe material and a packer material surrounding the pipe material, A construction method characterized in that a resin material is filled into the packer material in a gap stone area on the surface side of the ground including the reinforcing member, and a hardening material is filled into the packer material in a ground area on the back side of the ground including the reinforcing member.

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