JP2019015100A - How to remove the Yamato wall - Google Patents

Abstract

[PROBLEMS] To develop a method for removing a mountain retaining member without causing ground subsidence to the surrounding area, such as a neighboring land, in a place where there is a high risk that the surrounding ground will sink if the mountain retaining member such as a sheet pile is removed on soft ground. To do. A reinforcing layer forming step of inserting an injection pipe into the ground along the mountain retaining wall and injecting a ground hardening agent into the ground between the adjacent boundary line and the wall surface of the mountain retaining wall from the injection pipe. And the core material or the steel sheet pile wall from which the cement filler was pulled out after one or a plurality of core materials or steel sheet piles constituting the mountain retaining wall were drawn out. A method for removing a mountain wall including a step of filling a cavity in the ground. [Selection] Figure 1

Description

  The present invention relates to a method for removing a mountain wall.

The mountain retaining work is a work for protecting the side surface during excavation work and stopping the collapse of surrounding ground and the outflow of earth and sand. Yamato construction includes the parent pile method, sheet pile method, sheet pile method, and continuous underground wall (SMW) method.
When the mountain retaining member such as a sheet pile used for the mountain retaining is pulled out in the mountain retaining construction, a space corresponding to the volume of the mountain retaining member is generated in the ground. When voids are generated, the surrounding earth and sand move toward the generated voids, causing ground subsidence around the construction area and affecting groundwater. In addition, the building and the road surface around the site may be deformed.
Such effects include a method of leaving it to blend in with surrounding soil and a method of filling a void generated after pulling out a sheet pile by a method such as water tightening, sand filling, fluidized soil filling.
For example, Patent Document 1 discloses a mountain retaining method in which a groove is excavated and the both walls of the groove are fixed with a mountain retaining member, and the inside of the groove is worked. Is filled into the ground to fill the gap after the mountain retaining member is pulled out. By filling the void in the ground due to the withdrawal of the mountain retaining member with a hardening material, the pile member such as a sheet pile is pulled out. There is disclosed a construction method that does not cause a void in the ground and does not cause fluctuations in the surrounding ground and groundwater flow after construction and does not cause environmental problems (see FIG. 7).

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2006-148137) discloses a recess forming step for forming a recess by a machine or manual work around a mountain retaining member to be removed when the mountain retaining member is removed, By performing a drawing preparation step that fills the fluidized soil and a drawing step (see FIG. 8) for drawing the mountain retaining member with a crane, etc. A method for removing a retaining member that can reduce the cycle time required to pull out the retaining member and reduce the influence on the surrounding ground or the like is disclosed.

JP 2005-290963 A JP 2006-148137 A

  The present invention provides a method of removing a mountain retaining member without causing ground subsidence to the surrounding area such as a neighboring land in a place where there is a high risk that the surrounding ground will sink if the mountain retaining member such as a sheet pile is removed on soft ground. The purpose is to develop.

Before removing the mountain wall, the present invention forms a reinforced ground on the adjacent land side, pulls out the sheet pile, etc., and fills the extracted trace with a filler, thereby adversely affecting the adjacent land side. There is no way to remove the mountain wall.
The main configuration of the present invention is as follows.
1. A method for removing a mountain wall built in the ground,
A reinforcement layer forming step of inserting an injection pipe into the ground along the mountain retaining wall and injecting a ground hardening agent into the ground between the adjacent boundary line and the wall surface of the mountain retaining wall from the injection pipe,
In the ground where the core material or the steel sheet pile wall from which the cement filler was pulled out after one or a plurality of the core materials or steel sheet piles constituting the mountain retaining wall were pulled out Filling the cavity of
A method for removing a mountain retaining wall, comprising:
2. A method for removing a mountain wall built in the ground,
Injecting an injection pipe into the ground along the mountain wall, injecting a ground hardening agent into the ground between the adjacent boundary line and the wall surface of the mountain wall from the injection pipe,
The core material constituting the mountain retaining wall, or one or more steel sheet piles, and at the same time the core material or the steel sheet pile wall from which the cement-based filler has been drawn are built. Filling the cavity,
A method for removing a mountain retaining wall, comprising:
3. 1. A ground having a formation with an N value of 10 or less. Or 2. The removal method of the mountain wall described.
4). In the reinforcing layer forming step, the reinforcing layer is formed from the groundwater level surface to the upper part. ~ 3. The removal method of the mountain retaining wall in any one of.
5. In the reinforcing layer forming process,
The ground hardening agent is a pharmaceutical injection material mainly composed of water glass,
The ground hardening agent is injected in multiple steps. The first time, the ground hardening agent is injected into the entire reinforcing layer at a low concentration, and the ground hardening agent is injected close to the retaining wall so that the concentration is high. Features 1. ~ 4. The removal method of the mountain retaining wall in any one of.
6). In the ground having N strata with N value of 10 or less, the retaining wall is provided in the retaining wall removal trace, the reinforcing layer with the upper end above the groundwater level on the side adjacent to the retaining wall and the filling wall in the retaining wall withdrawal space. Reinforcement filling structure of the removal of the retaining ring.

1. The present invention, after removing a retaining member such as a sheet pile in soft ground, after reinforcing the ground on the boundary side of the adjacent land, and then filling the cement-based filler while pulling the retaining member, after removing the retaining wall It is possible to prevent adverse effects such as ground degradation around the area. In particular, foundation works in urban areas and gulf areas where the adjacent land boundary is approaching will not adversely affect the adjacent land such as land subsidence.
2. In particular, in the case of a construction site where the groundwater level is on the upper side of the wall height of the mountain retaining wall and the distance between the adjacent boundary line and the mountain retaining wall is narrow, in the stage before extracting the retaining wall, For the ground above the groundwater level between the wall and the wall of the Yamato wall, by increasing the permeability, when the mountain wall is pulled out, the ground subsidence between the adjacent boundary line and the mountain wall Can be prevented. Further, in the ground having a soft layer with an N value of 10 or less, particularly 5 or less, the holding power of the hollow portion from which the mountain retaining wall is pulled out is weak, and the environment in which softening is promoted by the influence of groundwater Valid below.
3. Since the removal space is filled with the cement filler in parallel with the removal work of the mountain retaining wall, the soil of the flexible ground does not enter the removal space.
4). As a step before pulling out the retaining wall, by injecting the chemical solution injection into the ground several times along the retaining wall (core material and steel sheet pile), the surrounding ground contacting the retaining wall The water permeability is reduced to form a concentration gradient in the waterstop, forming a reinforcing layer that strengthens the waterstop on the mountain retaining wall side, reducing the influence of groundwater on the reinforcing layer of the filler, and reducing the ground strength It can certainly be increased.
5. Since the retaining wall of the mountain retaining wall has a reinforcing layer formed on the adjacent land side and a filling layer is formed in the mountain retaining wall removal space, the vicinity of the boundary of the neighboring land is reinforced in a soft ground, and a stable layer Can be formed and the impact on the adjacent land can be mitigated even after the construction is completed.

The figure which shows the process of the removal method of a mountain retaining wall. Sectional drawing which shows the formation outline of a ground hardening agent injection | pouring and a reinforcement layer. The top view which shows the formation outline of a ground hardening agent injection | pouring and a reinforcement layer. Sectional drawing which shows the outline of the Yamato wall construction sheet pile drawing-out and the filling work of a filler. The top view which shows the outline of the Yamato wall construction sheet pile drawing-out, and the filling construction of a filler. The figure which shows a geological survey. The figure which shows the prior art example of patent document 1 indication. The figure which shows the prior art example of patent document 2 indication.

Before removing the retaining wall provided on the soft ground such as the soft ground, the present invention forms a reinforcing ground on the adjacent ground side, pulls out the sheet pile, and fills the pull-out trace with a filler. This is a method of removing a mountain wall that does not cause adverse effects such as terrain changes.
That is, the method of removing the retaining wall built in the ground is to insert an injection pipe into the ground along the retaining wall, and between the adjacent boundary line and the wall surface of the retaining wall. Reinforcing layer forming step of injecting ground hardener into the ground of the core, and the core material from which the cement filler is extracted after one or more core materials constituting the retaining wall or steel sheet piles are extracted Or the process which fills the cavity part in the ground in which the said steel sheet pile wall was erected.
Although the location where the mountain wall is constructed on the construction site is described as the location facing the adjacent land, this adjacent land not only means the land of others, but there are structures such as preservation buildings even in the owner's land The part to do is also included.

<Soft ground>
There is a technology to prevent the occurrence of cracks in the surrounding area by filling the sheet pile drawing space in Patent Literature 1 and Patent Literature 2, etc., but in the ground where the groundwater level is high and soft ground, Stability may not be maintained, especially when adjacent buildings are close, and care must be taken to prevent cracks and tilts in adjacent buildings.
When the grout was filled in the space where the sheet pile was pulled out on a soft ground, it collapsed and a nearby land subsidence occurred. One approach is to deal with post-processing that repairs the collapsed part, but if adjacent buildings are close, tilting the building will cause a serious accident, so consider a means of pulling out the sheet pile without causing collapse. As a result, prior to pulling out, we studied a method to reinforce the adjacent land side so that no adverse effects such as land subsidence occur on the adjacent land side.
The reason for the collapse is that the void wall does not have to be collapsed until the grout is cured and exhibits strength.
The preferred ground to which the present invention is applied is a soft ground, and when the trace of the sheet pile or the like is left as it is, the soil flows into the drawing space from the adjacent ground, and the adjacent ground is cracked or subsidized. It is the ground that is generated. As such a soft ground, the ground having an N value of 10 or less, and further 5 or less. Furthermore, when the groundwater level is high and there is a groundwater level at the upper part of the mountain retaining wall, it is easily fluidized due to the influence of water pressure, so that the soil easily enters the cavity and the void is easily collapsed. Such ground is distributed in landfills on the shores of the bay, near rivers, lakes, etc., especially in urban areas, there is no room for construction, and there is a mountain wall approaching the adjacent land. It is necessary to prevent the adjacent buildings and roads from being removed.
The soil condition will be confirmed by conducting a soil survey.

The basics of the Yamato wall removal process are shown in FIG. This process includes a reinforcing layer forming process 100, a sheet pile drawing operation 200, a filler injecting process 300, and a Yamato wall drawing trace reinforcing ground curing process 400.
Prior to the reinforcement layer formation process, the soil will be investigated, and the location of the groundwater level, the stratum structure and the N value of each layer will be investigated.
The reinforcing layer forming step 100 inserts an injection pipe into the ground along the mountain retaining wall, and injects a ground hardening agent into the ground between the adjacent boundary line and the wall surface of the mountain retaining wall from the injection pipe, This is a step of forming a reinforcing layer.
The sheet pile drawing operation 200 is an operation of pulling out the sheet pile with the earth retaining member drawing machine. By this drawing, a drawing space having a size larger than the cross section of the sheet pile is generated, for example, soil is attached to the sheet pile. Pull out one, two, or three sheet piles.
The filler injecting step 300 is a step of injecting a filler into the space where the earth retaining member such as a sheet pile has been pulled out to fill and prevent collapse.
The sheet pile drawing operation and filling material injection can be carried out after the drawing is finished or while being drawn out into a space formed under the sheet pile to be pulled up.

Regarding the relationship between the boundary of adjacent land and construction, the outer wall of the above-ground part has regulations such as retreating by 1 m or 1.5 m in accordance with the Building Standard Law etc., but there are no particular restrictions on underground structures.
In the present invention, the mountain retaining wall is constructed by retreating from the adjacent boundary by the amount of forming the reinforcing layer.

<Ground curing agent>
Examples of injecting agents used as a ground hardening agent for forming a reinforcing layer include water glass-based agents, special silica-based chemical solutions, and cement-based chemical solutions.
Water glass chemicals: Water glass chemicals are agents that are primarily effective in stopping water rather than uniting soil. It is a chemical that uses water glass as the main ingredient and causes cement to react with the suspension to solidify.
Alkaline, non-alkali (silica sol), water glass / cement mixed system, water glass / slag cement, water glass / acid reactant, water glass / metal reactant, water glass / alkali reactant, water glass・ There are organic reactants.
It has stable characteristics even under groundwater pressure, has excellent permeability, and has little gel time delay even when diluted with groundwater. The present invention is suitable as a reinforcing material for sandy soil to which the present invention is easily applied and soft ground having a high groundwater level.
As the instantaneous setting type, an inorganic reactant can be used to react in seconds.
As the intermediate or slow-binding type, an organic reactant is used, resulting in a reaction of several tens of minutes or more.
Special silica-based chemical solution: An agent for curing a suspension of ultrafine particles using a special grout as a curing agent.
Since the component is ultrafine particles, it has excellent permeability. Hard to be affected by soil quality and groundwater. Suitable for cohesive to sandy soils.
Cement-based chemical solution: Cement milk is condensed and hardened for a short time. Excellent long-term durability, but difficult to solidify when diluted with groundwater during injection.

Since the reinforcing layer is formed from the mountain retaining wall toward the adjacent land side, the risk of adversely affecting a workpiece such as an adjacent site or building is reduced even if a soil retaining member such as a sheet pile is pulled out.
In consideration of the fragility of the voids and the like, the filler generated in the ground after the drawing is appropriately selected to be filled while being drawn or after the drawing.
The ground hardening agent is injected once or twice. By dividing into two times, the vicinity of the mountain retaining wall can be strengthened, and the sheet pile drawing hole can be made more stable.

<Filler>
A cement bentonite chemical, fluidized soil, or the like can be used as the injection chemical for forming the filler layer.
Cement-based fillers include cement bentonite and cement milk.
Mixing bentonite with cement milk gives viscosity and improves waterstop. As a usage, it is used for a water blocking wall (underground continuous wall) for excavating the underground of a building.
The fluidized soil is a backfill material made by mixing water and cement into the construction residual soil. Filling by pumping or pouring can be performed. There is no risk of water stoppage and uneven settlement, and it is moderately hardened and can be re-excavated.
Cement milk is a mixture of cement and water, and is used as an injecting material for ground improvement in basic processing. What added various admixtures with water is also included in cement milk.

<Reinforcing layer formation method>
Examples of the reinforcing layer forming method include a double tube strainer method and a double tube double packer method.
A double pipe strainer method is used on the adjacent side of the sheet pile to infiltrate the reinforcing agent and strengthen the ground. The strengthening area is, for example, the construction range of the mountain retaining wall in the depth direction from the vicinity of the lower end of the seat pile to above the groundwater level surface, the width is within the boundary of the adjacent land (for example, within 100 cm), and the adjacent land length that requires the length. Within.
The double-pipe strainer method is a technology that uses a double-pipe rod to drill holes to the bottom of the planned depth of injection, and sends the main agent and reactant separately to the inner and outer pipes of the double-rod to improve the ground. The infiltration of the ground improvement agent is performed while pulling up sequentially from below.
After excavation, the instantaneous drug is roughly packed (grouting pack) around the injection tube, and then the intermediate binder or slow binder is injected into a limited target area. This is performed from the bottom to the top, stepping up sequentially. Demonstrates ground reinforcement and waterstop.
The double pipe strainer method seals around the rod with an instantaneous setting agent, so there is little dissipation of the injection agent from the periphery of the rod, and osmotic injection is performed on sandy soil, and homogeneous osmotic injection Is obtained. It exhibits a good reforming effect in order to treat the layer boundary of alternate layers with a hardening agent. In particular, the double-pipe strainer method exhibits a good improvement effect on sand, rake, and alternate layers.
In the double-pipe double packer method, the hole is drilled in the casing, the appearance for injection is inserted into the casing after drilling, and then the casing is pulled out, and seal grout is injected around the pipe to maintain the pipe space. In this method, an inner tube with a packer is inserted, and a primary injection of a drug such as a CB agent is performed to homogenize the ground, and then a solution type injection is infiltrated to improve. The double-pipe double packer method also shows a good improvement effect on sand, rubble and alternate layers.
In these methods, improvements are made while stepping up one drilling hole, the bowling machine is moved, and the operation is continued by moving to the next drilling hole.
In the present invention, the ground hardening agent is divided into two times, and the second time the injection amount is larger than the first time, so that the water stoppage and ground strength of the surrounding ground in contact with the mountain wall can be increased. Thereby, the space | gap side after drawing out a sheet pile is reinforced and stability improves.

<Filling method of filler>
As a filling method of the filler, there is a method of filling the filler after pulling out the sheet pile, or filling in parallel with the drawing of the sheet pile.
Since the reinforcing layer is formed on the adjacent side of the mountain retaining wall, it is stable and can be filled after the sheet pile is pulled out, or can be filled at the same time.
For these filling methods, methods disclosed in Patent Documents 1 and 2 can be employed.

In this embodiment, the removal of the large mountainside retaining wall was conducted in advance, while the soil wall was surveyed when pulling out the mountain retaining wall installed near the neighboring land side and the large mountain retaining wall on the neighboring land side. The construction was confirmed and the impact was confirmed.
The results of the soil survey are shown in FIG.
The groundwater level is high at a depth of 2.5m. As for soil quality, silt layer and sandy layer overlap. As a layer having an N value of 5 or less, it is found in silt layers and sandy silt-type layers, and is seen in fine sand layers mixed with sand and silt. In the layer having an N value of 10 or less, it can be seen in fine sand and fine sand mixed with silt.

(Prior investigation work)
A method of filling the filler from the lower side simultaneously with the drawing of the sheet pile without forming a reinforcing layer was adopted.
In the drawing, the steps corresponding to FIGS. 4 and 5 (where there is no adjacent building) were performed.
The mountain retaining wall is configured using the sheet pile 31. After the drawn sheet pile 32, using a filler injection machine, cement-based bentonite is injected from the rod as a filler 21 into the extraction gap to form the packed layer 2. Before the sheet pile is pulled out, the vicinity of the ground part of the sheet pile is dug down to engrave a cloth tension part for monitoring the liquid level to provide a liquid pool.
As a result, cracks and land subsidence occurred around the area. In the normal drawing and filling method, this construction will have an adverse effect on the adjacent land, such as an adjacent building near the construction site.
This was presumed that the sandy layer collapsed due to the high groundwater level.

(Main work)
In this construction, as a result of examining a method that does not adversely affect the adjacent side of the mountain wall, a reinforcement layer was formed on the adjacent side prior to the removal of the sheet pile. In particular, considering that the influence of high groundwater level does not affect the hardening and sheet pile drawing holes, a water glass system was used as a reinforcing agent that has a high water-stopping property and progresses to gelation even when diluted with water.
The cement bentonite system was adopted as the agent for filling the sheet pile drawing holes. Cement-based bentonite is a binding agent that also exhibits water-stopping properties and is suitable for this construction site.
The construction site is 1000 mm to the adjacent boundary, and the building is approaching the boundary near the boundary. The geological conditions of the site are as described above, and the groundwater level is 2.5m.

As for the construction process, the soil investigation and the preceding investigation work are performed mainly in Fig. 1.
The description of the process is as described above. A reinforcing layer forming step 100, a sheet pile drawing operation 200, a filler injecting step 300, and a Yamato wall drawing trace reinforcing ground curing step 400 are provided.
The reinforcing layer forming step 100 inserts an injection pipe into the ground along the mountain retaining wall, and injects a ground hardening agent into the ground between the adjacent boundary line and the wall surface of the mountain retaining wall from the injection pipe, This is a step of forming a reinforcing layer.
The sheet pile drawing operation 200 is an operation of pulling out the sheet pile with the earth retaining member drawing machine.
The filler injecting step 300 is a step of injecting a filler into the space where the sheet pile has been pulled out to fill and prevent collapse.
The Yamadome wall extraction trace reinforcement ground curing process 400 is a curing process in which the filler is cured and stabilized.

The reinforcing layer forming process is shown in FIGS.
The construction site A approaches the building of the adjacent land B, and the mountain retaining wall 3 is constructed about 1000 mm below the adjacent boundary 8.
Since the upper end of the sheet pile protrudes, the embankment 14 is performed on the construction site side in order to install the reinforcing agent injector.
The reinforcing agent injector 4 is installed on the embankment 14 and inserted into the lower end 32 of the sheet pile 31 into which the rod 42 is driven, and a solution type water glass chemical as a reinforcing agent by a double-phase strainer method multiphase type. Injected. The rods 41a... 41n are sequentially inserted in the length direction of the mountain retaining wall 3 at intervals of 1 m, and the reinforcing material is injected while moving the reinforcing material injector 4a to 4b. The injection distance of the reinforcing material into the soil is adjusted to have a radius of 1000 mm. The setting of the injection distance is determined by performing a trial process in advance. In this example, since it will inject | pour between adjacent rods, a reinforcement layer is formed over the full length, without being interrupted. The interval between the injection rods is not limited to this, and can be set within a continuous range. As shown in FIG. 3, the reinforcing layer 1 was formed along the adjacent building 7. The progress of the injection speed, etc. was advanced in consideration of the fluctuation of the pole 8 built on the adjacent land side.
The reinforcing layer 1 was formed at a depth of 1000 mm from the bottom to the top of the sheet pile, and a thickness of 1000 mm on the front side of the mountain retaining wall.

The filling layer forming process is shown in FIGS.
A cloth digging unit 23 for monitoring the liquid level is provided on the ground part of the mountain retaining wall 3, the filler injection machine 5 is installed at one end of the mountain retaining wall 3, and the sheet pile 31 is sequentially pulled out from one end by the puller 6, Filler sentiment bentonite was injected from below with a rod 22 to form a packed bed 2.
Although the lower ends of the reinforcing layer 1 and the filling layer 2 are the same, the lower end of the filling layer is formed to be the same as or above the lower end of the reinforcing layer so as not to be affected by groundwater. The upper part of the packed bed is formed substantially up to the ground part and is in contact with the cloth digging part 23. Since the filler is injected to the above-ground part, a cloth digging part is provided so that the agent does not leak and the liquid level of the filler is monitored.
The length of the filling layer 2 was the same as that of the reinforcing layer 1.
Filler is 42.0 m ² for a pile area of 42.0 m ² , which is obtained by multiplying the injection height of 7.5 m corresponding to the embedding depth of the sheet pile embedded in the ground by the ground surface length of 5.6 m. , it was charged with design plan injection amount 4410M ³ multiplied by the infusion rate 105L / ^{m 2.}

The reinforcing agent used was water glass as a main material, and a curing agent for instantaneous setting was used as a curing agent. The gel time was set within 10 seconds.
The cement bentonite used was prepared by mixing ordinary cement and bentonite in water. The 28 day intensity is 1.5 MN / m ² .

  By combining this reinforcing layer and packed bed, it was possible to remove the mountain retaining wall without causing cracks or settlement on the adjacent land side.

The formation of the reinforcing layer is the same as in Example 1 except that the reinforcing agent is injected in two steps.
As the first injection, the same reinforcing agent as in Example 1 was injected, and the second time, a water glass-based agent using a hardening agent for slowing was injected.
Specifically, in the first round, the target soil volume is obtained by multiplying the height of the injection of the reinforcing agent by 6.5 m and the flat area of the injection range of 7.1 m ² (the range of the ground width of 1.0 m in front of the mountain retaining wall). 5% was filled as a soil injection rate for 46.15 m ³ , and 20% was filled as a soil injection rate with respect to the target soil amount in the second time. In the first injection, a thin layer was formed, and in the second injection, the concentration on the mountain retaining wall side was increased to further improve the water stoppage.
The water stoppage was confirmed by creating a test body.

DESCRIPTION OF SYMBOLS 1 Reinforcement layer 11 Injection pipe 12 Front end 13 Lower end 14 Filling 2 Filling layer 21 Filling material 22 Rod 23 Fabric moat 3 Yamato wall 31 Sheet pile 32 Sheet pile lower end 4 Reinforcing agent injection machine 41 Injection rod 5 Filling material injection machine 7 Adjacent building 8 Adjacent border 9 pole

DESCRIPTION OF SYMBOLS 100 Reinforcement layer formation process 200 Sheet pile extraction operation 300 Filler injection process 400 Yamadome wall extraction trace reinforcement ground curing process

A Construction site B Adjacent land

Claims (6)

A method for removing a mountain wall built in the ground,
A reinforcement layer forming step of inserting an injection pipe into the ground along the mountain retaining wall and injecting a ground hardening agent into the ground between the adjacent boundary line and the wall surface of the mountain retaining wall from the injection pipe,
In the ground where the core material or the steel sheet pile wall from which the cement filler was pulled out after one or a plurality of the core materials or steel sheet piles constituting the mountain retaining wall were pulled out Filling the cavity of
A method for removing a mountain retaining wall, comprising: A method for removing a mountain wall built in the ground,
Injecting an injection pipe into the ground along the mountain wall, injecting a ground hardening agent into the ground between the adjacent boundary line and the wall surface of the mountain wall from the injection pipe,
The core material constituting the mountain retaining wall, or one or more steel sheet piles, and at the same time the core material or the steel sheet pile wall from which the cement-based filler has been drawn are built. Filling the cavity,
A method for removing a mountain retaining wall, comprising:   The method for removing a mountain retaining wall according to claim 1 or 2, wherein the ground has an N value of 10 or less.   The method for removing a mountain wall according to any one of claims 1 to 3, wherein in the reinforcing layer forming step, the reinforcing layer is formed from the groundwater level surface to the upper part. In the reinforcing layer forming process,
The ground hardening agent is a pharmaceutical injection material mainly composed of water glass,
The ground hardening agent is injected in multiple steps. The first time, the ground hardening agent is injected into the entire reinforcing layer at a low concentration, and the ground hardening agent is injected close to the retaining wall so that the concentration is high. The removal method of the mountain retaining wall in any one of Claims 1-4 characterized by these.   In the ground having N strata with N value of 10 or less, the retaining wall is provided in the retaining wall removal trace, the reinforcing layer with the upper end above the groundwater level on the side adjacent to the retaining wall and the filling wall in the retaining wall withdrawal space. Reinforcement filling structure of the removal of the retaining ring.

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