Slope restoration method

Abstract

We provide a slope restoration method that can shorten the construction period and reduce construction costs. [Solution] A slope restoration method for restoring a collapsed slope, comprising an emergency treatment step to prevent the collapse from progressing, and a restoration step after the emergency treatment step to widen the top surface and set back the slope by performing embankment, wherein the emergency treatment step includes step A of installing a first stone-filled cage at a position adjacent to the newly formed slope due to the collapse, and the restoration step includes step B of installing a second stone-filled cage in the ground at a position away from the first stone-filled cage, and step C of filling a filler material between the first stone-filled cage and the second stone-filled cage.

Description

Technical Field

[0001] The present invention relates to a slope restoration method.

Background Art

[0002] In recent years, due to climate change, heavy rainfall (torrential rain) has frequently occurred in a short period of time. As a result, landslides have also occurred frequently.

[0003] Among such landslides, there are disasters in which the constructed ground such as roads and railway lines collapses. When such disasters occur, the transportation network stops, causing great obstacles to daily life.

[0004] For example, on highways, there are places where the ground supporting the road is formed by embankments. In such places, the side of the road is a slope. When this slope collapses due to heavy rain, the road itself may collapse, or even if the road does not collapse, a part under the road may collapse, resulting in a situation where a part of the supporting ground of the road disappears.

[0005] In such cases, conventionally, for temporary emergency measures, work has been carried out to support the road with large sandbags, and then full-scale restoration work using stone cages as disclosed in Patent Document 1 has been carried out.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, using large sandbags for emergency repairs meant that their ability to maintain their shape and support the road was lost over time. Therefore, in full-scale restoration work, the sandbags had to be removed first, and then stone-filled cages or concrete retaining walls that could maintain a stable structure for a long period of time had to be installed, which resulted in increased costs and longer construction times. In addition, because sandbags have poor water permeability, if it rained between the emergency repairs and full-scale restoration work, the remaining supporting ground of the road would absorb a large amount of water and become prone to collapse.

[0008] This invention has been made in view of the above, and its purpose is to provide a slope restoration method that can shorten the construction period and reduce construction costs. [Means for solving the problem]

[0009] A means to solve the above problems is a slope restoration method for restoring a collapsed slope, comprising an emergency treatment step to prevent the collapse from progressing, and a restoration step after the emergency treatment step to widen the top surface and set back the slope by performing embankment, wherein the emergency treatment step includes step A of installing a first stone-filled cage at a position adjacent to the newly formed slope due to the collapse, and step C of filling the newly formed slope and the first stone-filled cage with a permeable backfill material, and the restoration step includes step B of installing a second stone-filled cage in the ground at a position away from the first stone-filled cage, and step C of filling the space between the first stone-filled cage and the second stone-filled cage with a permeable filler material.

[0010] Here, embankment refers to piling up soil and other materials to form a horizontal surface on top of it. Expanding the top surface and receding the slope means that the horizontal surface formed by the embankment becomes part of the top surface, thus expanding the top surface, and as the top surface expands, the slope moves away from its original position, thus receding. The position adjacent to the newly formed slope due to the collapse refers to the position adjacent to the newly formed slope due to the collapse or a position slightly away from that slope. If there is a gap between the first stone-filled cage and the newly formed slope due to the collapse, it is preferable to fill that gap with soil, crushed stone, etc. Note that the slope after the collapse may be referred to as the "newly formed slope due to the collapse" as is, or the slope after the collapse may be prepared to facilitate emergency repairs and then referred to as the "newly formed slope due to the collapse".

[0011] In step C, the first stone-filled basket and the second stone-filled basket may be connected by a connecting member.

[0012] In step C, the filler material may be filled to a position lower than the upper end of the first stone-filled basket, then the first stone-filled basket and the second stone-filled basket may be connected by a connecting member, and then the filler material may be filled up to the upper end of the first stone-filled basket.

[0013] The first stone-filled cage may support a structure installed on its top surface.

[0014] The aforementioned filler material may be permeable to water. A permeable filler material is a coarse-grained drain material with a larger particle size than soil and good permeability, and examples include gravel, crushed stone, crushed rock, and crushed concrete.

[0015] In step A, the first stone-filled cage, which is filled with stones, may be lifted, moved, and installed. [Effects of the Invention]

[0016] In order to directly use the gabion, which is a restoration member used in emergency response, in the full-scale restoration process, it is possible to ensure the drainage performance after the emergency response, and reduce the cost and construction time of the entire restoration work.

Brief Description of the Drawings

[0017] [Figure 1] It is a cross-sectional view perpendicular to the longitudinal direction of the road. [Figure 2] It is a cross-sectional view of the road in Fig. 1 and a part of its ground in a collapsed state. [Figure 3] It is a cross-sectional view of the state where the collapsed part in Fig. 2 is removed and leveled. [Figure 4] It is a cross-sectional view of the state where the emergency response process according to the embodiment is carried out. [Figure 5] It is a cross-sectional view of the start state of the restoration process according to the embodiment. [Figure 6] It is a cross-sectional view of the state showing Process C according to the embodiment. [Figure 7] It is another cross-sectional view of Process C according to the embodiment. [Figure 8] It is another cross-sectional view of Process C according to the embodiment. [Figure 9] It is a cross-sectional view of the state where Process C according to the embodiment is completed. [Figure 10] It is a cross-sectional view of the state where the restoration process and road reconstruction according to the embodiment are completed.

Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. The following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present invention, its applications, or its uses. In the following drawings, for the sake of simplicity of explanation, components having substantially the same functions are denoted by the same reference numerals.

[0019] (Embodiment 1) Figure 1 is a cross-sectional view of a road perpendicular to its longitudinal direction. The road 400 is formed on the top surface 200, which is the upper surface of the ground 100, and the sides of the road 400 are slopes 300.

[0020] Figure 2 shows a cross-section of the road and slope in Figure 1 after they have collapsed due to heavy rain. The ground 100 supporting the road 400 has loosened and collapsed due to the heavy rain, causing the road 400 to also collapse. The slope 310 after the collapse is in an unstable state where further collapse will occur if it rains again. Therefore, in order to prevent further collapse of the slope 310, emergency repair work will be carried out as quickly as possible after the collapse.

[0021] Conventional emergency repair methods prioritize urgency and involve piling up sandbags along the collapsed slope 310. However, sandbags have poor water permeability, so when it rains, water accumulates in the soil and other materials inside the slope 310, loosening the ground. In such a state, there is a risk of the ground collapsing. Furthermore, in full-scale restoration work, sandbags need to be removed due to their low strength and poor water permeability and replaced with other civil engineering construction materials such as stone-filled cages.

[0022] The emergency repair process according to this embodiment involves first leveling the slope 310 to a predetermined gradient slope 320 as shown in Figure 3, and removing the damaged portion of the road 400. Then, as shown in Figure 4, installing a first stone-filled cage 10 for emergency repair along the slope 320 (Step A). ​​In this embodiment, the first stone-filled cage 10 is stacked in five layers. A permeable backfill material 12 (e.g., single-size crushed stone) is placed between the slope 320 and the first stone-filled cage 10. In order to prevent soil and sand from entering the backfill material 12 from the slope 320, it is preferable to install a sheet-like erosion prevention material made of nonwoven fabric or the like on the slope 320 that allows water to pass through but not soil and sand, before placing the backfill material 12 between the slope 320 and the first stone-filled cage 10.

[0023] In other words, in the emergency repair process according to this embodiment, the collapsed slope 310 is leveled to create a newly formed slope 320. Next, a suction prevention material is installed on the newly formed slope 320. Then, the first stone-filled cage 10 is installed in a position adjacent to the slope 320. The first stone-filled cage 10 is a cage made of wire mesh filled with filling material (stones, crushed stone, broken gravel, concrete fragments generated from demolished structures, etc.). Since the filling material has excellent water permeability, even if it rains, water is quickly discharged to the outside of the first stone-filled cage 10. As for the method of installing the first stone-filled cage 10, a cage may be formed by assembling wire mesh in a position adjacent to the slope 320 and filling it with filling material to form the first stone-filled cage 10, or the first stone-filled cage 10 may be formed and filled in a different location and then lifted by a crane or the like and installed in a position adjacent to the slope 320. In the latter case, it is preferable to use a stone-filled cage as disclosed in Patent Document 2, as the stone-filled cage can be formed and filled in a location that is easy to assemble, thus reducing time and cost.

[0024] Since the first stone-filled basket 10 is roughly rectangular, a gap is created between the slope 320 and the first stone-filled basket 10. Therefore, backfill material 12 is placed between the slope 320 and the first stone-filled basket 10 to the same height as the first stone-filled basket 10. Then, the second first stone-filled basket 10 is placed on top of the first first stone-filled basket 10 and the backfill material 12. After that, backfill material 12 is placed between the slope 320 and the second first stone-filled basket 10. The same process is repeated to stack five first stone-filled baskets 10, resulting in the state shown in Figure 4, and the emergency repair process is completed. If the road 400 is not completely destroyed and a portion remains, and that portion is passable, the remaining portion of the road becomes passable after the emergency repair is completed.

[0025] Once the emergency repair process is complete, the slope 320 is protected by the first stone-filled cage 10 and drainage is also provided, so the slope 320 will not collapse even when it rains. Next, construction work to rebuild the collapsed road is carried out. This reconstruction work takes time to prepare, so it is usually carried out several weeks to several months after the completion of the emergency repair process. In rebuilding the road, first an embankment is made to form the base, and then the slope restoration process is carried out to widen the top surface and set back the slope. The road is then rebuilt on top of the widened top surface.

[0026] In the restoration process, as shown in Figure 5, the second stone-filled cage 20 (first stage) is first installed at the toe of the slope when the top surface is widened and the slope is set back. The location where the second stone-filled cage 20 is installed is on the ground at a distance from the first stone-filled cage 10 (process B). The second stone-filled cage 20 may be the same as the first stone-filled cage 10 (size, material, type of filling material, etc.), or a different stone-filled cage may be used. In Figure 5, the height of the first stone-filled cage 10 and the second stone-filled cage 20 are the same. The method of installing the second stone-filled cage 20 is the same as the first stone-filled cage 10; the wire mesh may be assembled on-site and the filling material may be packed in, or the second stone-filled cage 20 may be formed in a different location and then lifted and installed using a crane or the like.

[0027] Next, as shown in Figure 6, the filling material 30 is placed between the first stone-filled basket 10 and the second stone-filled basket 20 of the first stage to approximately half the height of the first and second stone-filled baskets 10 and 20, and the surface is leveled and compacted to perform the filling (step C1). Various materials such as soil and crushed stone can be used for the filling material 30, but it is preferable to use a material that has water permeability to quickly drain rainwater (for example, gravel, crushed stone, crushed rock, crushed concrete, etc.), and in this embodiment, crushed stone is used as the filling material 30. Therefore, even if it rains heavily, rainwater can be quickly drained to the outside and the embankment can be prevented from collapsing.

[0028] Then, as shown in Figure 7, the first stone-filled cage 10 and the second stone-filled cage 20 are connected by a connecting member 35. The connecting member 35 connects the first stone-filled cage 10 and the second stone-filled cage 20 and is made of a material with high tensile strength. Examples include iron wire or wire mesh with rust-proofing treatment on the surface, steel material, rope or mesh made of synthetic resin, or a combination of the above. For example, using iron wire for the connecting member 35 is preferable in terms of effort and cost because it allows the cages to be connected with less material and the connection between the cage and the iron wire can be easily made.

[0029] Next, as shown in Figure 8, filling material 30 is placed on the connecting member 35 between the first stone-filled basket 10 and the second stone-filled basket 20 to approximately the same height as the top surfaces of the first and second stone-filled baskets 10 and 20, and the surface is leveled and compacted to perform the filling (step C2). This filling integrates the first and second stone-filled baskets 10 and 20 with the connecting member 35 and the filling material 30, thereby preventing the second stone-filled basket 20 from sliding and shifting due to back pressure.

[0030] Next, the second layer of the second stone-filled basket 20 is placed on top of the first layer of the second stone-filled basket 20 and the packing material 30. The second layer of the second stone-filled basket 20 is positioned at a location that has a predetermined slope in relation to the first layer of the second stone-filled basket 20. Then, steps C1 and C2 are performed to fill the space between the first and second stone-filled baskets 10 and 20 of the second layer with packing material 30 and connect the first and second stone-filled baskets 10 and 20 of the second layer with connecting members 35. This is repeated to stack the second stone-filled baskets 20 in five layers as shown in Figure 9, and each second stone-filled basket 20 is connected to the first stone-filled basket 10 with connecting members 35, and the space between the first and second stone-filled baskets 10 and 20 is filled with packing material 30.

[0031] Next, a stone-filled basket 22 is placed on top of the second stone-filled basket 20, which is the fifth layer. This stone-filled basket 22 may be the same as the second stone-filled basket 20 or a different one. Then, as shown in Figure 10, another stone-filled basket 24 is placed on top of the stone-filled basket 22, and the subgrade 50 is placed on top of the filling material 30 and the first stone-filled basket 10, which is the fifth layer. For the subgrade 50, cement-improved soil is used, for example. At this time, it is preferable to install a sheet-like erosion prevention material on top of the filling material 30 and on the back side of the stone-filled baskets 22 and 24. After the restoration work in which the top surface is widened and the slope is set back by this embankment work, the road 400 is installed on top of the subgrade 50. The first stone-filled basket 10 is located beneath the road 400, and the first stone-filled basket 10 supports the road 400.

[0032] In this embodiment, the first stone-filled basket 10 is used for emergency measures after a slope collapse, and the first stone-filled basket 10 is also used for full-scale restoration work. Compared to using sandbags for emergency measures, costs and construction time can be reduced. Furthermore, the first and second stone-filled baskets 10 and 20 are connected by a connecting member 35, and the connecting member 35 is embedded and fixed in the filling material 30. As a result, the second stone-filled basket 20 is integrated with the first stone-filled basket 10 and the filling material 30, preventing it from shifting due to back pressure. In other words, since there is no need to install the stone-filled baskets in the space where the filling material 30 is filled, costs and construction time can be reduced.

[0033] (Embodiment 2) Embodiment 2 is a construction method that does not use the connecting member 35 as in Embodiment 1, except that it is otherwise the same as Embodiment 1. Because the connecting member 35 is not used, costs and construction time can be further reduced. In addition, if the connecting member 35 is not used, the second stone-filled cage 20 cannot be integrated with the first stone-filled cage 10 and the filling material 30, but this is not a particular problem if the structure has low back pressure.

[0034] (Other embodiments) The embodiments described above are illustrative examples of the present invention, and the present invention is not limited to these examples. These examples may be combined with or partially replaced with well-known, conventional, or prior art. Modified inventions that would be easily conceived by a person skilled in the art are also included in the present invention.

[0035] In Embodiment 1, the collapsed slope 310 was leveled to form a new slope 320. However, the collapsed slope 310 may be left as is, and the emergency repair process may be carried out using it as a newly formed slope resulting from the collapse.

[0036] The number of layers in which the first stone-filled cages are stacked is not particularly limited; the number of layers should be determined according to the height of the embankment. Similarly, the number of layers in which the second stone-filled cages are stacked should be determined according to the function required of the retaining wall.

[0037] A base drainage layer extending to the toe of the slope may be provided below the first and second stone-filled baskets at the bottom. The base drainage layer consists of a permeable drain material (such as crushed stone). The backfill material may be made of a material with low permeability.

[0038] The connecting member may be connected at any position, not just the center of the cage in the height direction. Furthermore, the method of connecting the connecting member to the cage is not particularly limited. It is also preferable to divide the connecting member into multiple parts and adjust the length at the installation site. [Explanation of Symbols]

[0039] 10 The first stone-filled basket 20. Second stone-filled cage 30 Filling material 35 Connecting member 320 Slope

Claims

1. A slope restoration method for restoring collapsed slopes, It includes an emergency repair process to prevent further collapse, and a restoration process that involves filling the top surface with earth and receding the slope after the emergency repair process. The emergency repair process includes step A of installing a first stone-filled cage at a position adjacent to the newly formed slope due to the collapse, and step A of inserting a permeable backfill material between the newly formed slope and the first stone-filled cage. The restoration process includes step B of installing a second stone-filled cage in the ground at a location away from the first stone-filled cage, and step C of filling the space between the first stone-filled cage and the second stone-filled cage with a filler material, wherein the slope restoration method is described above.

2. The slope restoration method according to claim 1, wherein in step C, the first stone-filled basket and the second stone-filled basket are connected by a connecting member.

3. The slope restoration method according to claim 2, wherein in step C, the filler material is filled to a position lower than the upper end of the first stone-filled basket, then the first stone-filled basket and the second stone-filled basket are connected by the connecting member, and then the filler material is filled up to the upper end of the first stone-filled basket.

4. The slope restoration method according to any one of claims 1 to 3, wherein the first stone-filled cage supports a structure installed on the top surface.

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