JP7085464B2 - How to build a retaining wall structure in the reverse striking method - Google Patents

Description

The present invention relates to a method for constructing a retaining wall structure using an existing underground outer wall.

Patent Document 1 shows a method of constructing a retaining wall structure using an existing underground outer wall left after demolition in a rebuilding work for constructing a new structure by dismantling an existing structure provided with an underground structure. A method of dismantling and constructing a building has been proposed. In this conventional method, the buttress construction step of constructing the buttress reinforcing body 5 inside the existing side wall portion (existing underground outer wall) 3a of the existing lower structure 3 and the buttress reinforcing body 5 inside the existing side wall portion 3a and with the buttress reinforcing body 5. The process of constructing the new side wall portion 6 of the new underground skeleton 2 with the outer space provided between them, and the existing side wall portion 3a including the new side wall portion 6 of the new underground skeleton 2 and the buttress reinforcing body 5. A filling step of filling the outer space between the concrete grouts 7 is provided.
Then, by executing the above-mentioned filling step, the existing side wall portion 3a and the side wall portion 6 of the new underground skeleton 2 are integrated, and a retaining wall structure composed of the existing side wall portion 3a including the buttress reinforcing body 5 and the concrete grout 7 is constructed. To.

Japanese Unexamined Patent Publication No. 2001-303599

In the conventional method of constructing the retaining wall structure, after the new side wall portion 6 of the new underground skeleton 2 is constructed at the inner position of the existing side wall portion 3a, the new side wall portion 6 and the buttress reinforcing body 5 including the buttress reinforcing body 5 are used. The outer space between them is filled with concrete grout 7. As a result, the existing side wall portion 3a and the new side wall portion 6 of the new underground skeleton 2 are integrated. Until the filling step of the concrete grout 7 is completed, the existing side wall portion 3a is only reinforced by the buttress reinforcing body 5. Therefore, in the case of rebuilding work in which the new underground skeleton 2 has many (deep) layers and a large earth pressure acts on the existing side wall portion 3a, the horizontal direction with respect to the earth pressure of the retaining wall structure using the existing side wall portion 3a. There is room for improvement in this respect, as the tension in the area is not sufficient.
Moreover, in constructing the new side wall portion 6 of the new underground skeleton 2, a large number of outer formwork, inner formwork, separator, etc. are required, and the outer end portion of the separator is the existing side wall portion 3a and the buttress reinforcing body 5. Since the separator is connected to the above, the length of the separator is also longer than the thickness of the new side wall portion 6, and there is room for improvement in terms of construction cost and construction accuracy of the new side wall portion 6.

In view of this situation, the main subject of the present invention is the construction of a mountain retaining wall structure in a reverse striking method capable of improving the resistance to the horizontal force of the retaining wall structure using the existing underground outer wall while reducing the construction cost. The point is to provide a method.

The first characteristic configuration of the present invention is a reverse striking method for a new underground structure constructed at a position where a space is provided inside the existing underground outer wall and the inner surface of the existing underground outer wall, and which is later constructed by a reverse striking method. The guide wall construction process that constructs the guide wall at the position where the tension force is applied from the inside at the construction site,
The space between the existing underground outer wall and the guide wall is filled with a filler, and a filler filling step of constructing a retaining wall structure including the existing underground outer wall, the filler and the guide wall is provided .
In the guide wall construction step, the upper end portion and the lower end portion of the guide wall are constructed in a state of being integrated with the existing floor slab on the upper floor side and the existing floor slab on the lower floor side .

According to the above configuration, the guide wall located inside the existing underground outer wall is subjected to a horizontal tension force from the inside at the reverse striking method construction site of the new underground structure to be constructed by the reverse striking method later. Built in position. Moreover, the space provided between the guide wall and the inner surface of the existing underground outer wall is filled with a filler, and a retaining wall structure in which the existing underground outer wall and the guide wall are integrated with the filler is constructed. As a result, it is possible to act as a girder at the reverse striking construction site of the new underground structure and improve the resistance to the horizontal force (earth pressure) of the retaining wall structure using the existing underground outer wall. Moreover, the construction cost can be reduced as compared with the case where the entire structure of the retaining wall composed of the existing underground outer wall, the filler and the guide wall is made of reinforced concrete or the like.
The second characteristic configuration of the present invention is that in the guide wall construction step, concrete is poured into the guide wall construction portion of the existing floor slab with the reinforcing bars arranged in the guide wall passed through the guide wall. Is integrated with the existing floor slab.

It is preferable to execute the existing underground outer wall reinforcing step for reinforcing the existing underground outer wall before performing the guide wall construction step.

According to the above configuration, the bending and shearing strength of the existing underground outer wall can be enhanced by reinforcing the existing underground outer wall with a buttress or the like before constructing the guide wall.

The third characteristic configuration of the present invention is to construct the guide wall at the design outer surface position of the reverse striking method construction site of the new underground structure to be constructed later in the guide wall construction step.

According to the above configuration, when constructing the reverse striking method construction site by the reverse striking method with the guide wall as the outer formwork, the inner surface of the guide wall is located at the design outer surface position of the reverse striking method construction site. It is not necessary to increase the thickness of the part more than necessary. Therefore, it is possible to reduce the amount of additional concrete cast on the outside of the main structure. Furthermore, the length of the separator that holds the position of the inner formwork can be shortened to the thickness of the new wall of the new underground structure, improving the position holding performance of the inner formwork and the safety of construction, and the construction cost of the separator. Can be cheaper.

The fourth characteristic configuration of the present invention is a reverse striking method for a new underground structure constructed at a position where a space is provided inside the existing underground outer wall and the inner surface of the existing underground outer wall, and which is later constructed by a reverse striking method. The guide wall construction process that constructs the guide wall at the position where the tension force is applied from the inside at the construction site,
The space between the existing underground outer wall and the guide wall is filled with a filler, and a filler filling step of constructing a retaining wall structure including the existing underground outer wall, the filler and the guide wall is provided.
In the filler filling step, a wall opening is formed in the guide wall and a floor opening is formed in the existing underground slab between the guide wall and the existing underground outer wall before the filler filling step is performed. The point is that the filler is dropped into the space on the lower floor side from the inside of the guide wall on the upper floor side through the wall opening and the floor opening.

According to the above configuration, the guide wall located inside the existing underground outer wall is subjected to a horizontal tension force from the inside at the reverse striking method construction site of the new underground structure to be constructed by the reverse striking method later. Built in position. Moreover, the space provided between the guide wall and the inner surface of the existing underground outer wall is filled with a filler, and a retaining wall structure in which the existing underground outer wall and the guide wall are integrated with the filler is constructed. As a result, it is possible to act as a girder at the reverse striking construction site of the new underground structure and improve the resistance to the horizontal force (earth pressure) of the retaining wall structure using the existing underground outer wall. Moreover, the construction cost can be reduced as compared with the case where the entire structure of the retaining wall composed of the existing underground outer wall, the filler and the guide wall is made of reinforced concrete or the like.
Further, according to the above configuration, in the filler filling step, the filler is dropped into the space on the lower floor from the inside of the guide wall on the upper floor through the wall opening and the floor opening, so that the filler is filled without gaps. It can be reliably filled.

The fifth characteristic configuration of the present invention is that fluidized soil is used as the filler.

According to the above configuration, since the fluidized soil has high fluidity, it can be reliably filled without forming a gap between the existing underground outer wall and the guide wall. Moreover, since fluidized soil is used as the filler, it can be filled at a lower cost than concrete. Therefore, it is possible to improve the workability of the retaining wall structure composed of the existing underground outer wall, the filler, and the guide wall, and to reduce the cost.

A vertical sectional view and a horizontal sectional view showing an existing underground outer wall reinforcement process in the method for constructing a retaining wall structure in the reverse striking method of the present invention. Vertical cross-sectional view and horizontal cross-sectional view showing the guide wall construction process Vertical cross-sectional view at the start of filling in the filler filling process Vertical cross-sectional view and horizontal cross-sectional view when filling of the filler filling process is completed Vertical cross-sectional view and horizontal cross-sectional view showing the construction process of a new underground structure by the reverse striking method

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a state in the middle of rebuilding work in which an existing structure 1 having an underground structure portion 1A and an above-ground structure portion is dismantled and a new structure is constructed above the existing pressure plate 2 left after the dismantling. ..

The existing structure 1 shown in FIG. 1 is a general building made of steel-framed reinforced concrete. In FIG. 1, the existing underground structure 1A from the first basement floor B1 to the fifth basement floor B5, which is a part of the dismantled existing structure 1, is left. The existing underground structure (existing underground skeleton) of the existing underground structure portion 1A consists of an existing pressure plate 2 which is the bottom of the existing foundation and an existing foundation beam which is constructed in a grid pattern on the upper surface side of the existing pressure plate 2. 3 and the existing underground outer wall 4 having a height from the 1st basement floor B1 to the 5th basement floor B5 continuously on the outer peripheral portion of the existing pressure plate 2, and the existing floor slab 5 of the 1st basement floor F1 to the 4th basement floor B4. Be prepared.

In the existing foundation pit space 6 from the upper surface 2a of the existing pressure plate 2 to the top end 3a of the existing foundation beam 3, the fluidized soil 11 as a filler is at the same height as the top end 3a of the existing foundation beam 3. It is filled. At the top surface 11a of the filled fluidized soil 11 and the top 3a of the existing foundation beam 3, the structure pillar 7 is built via the preceding mortar 12 and the structure pillar 7 is built by the reverse striking method. A new underground structure (new underground skeleton) 50 will be constructed. Among them, the axial force of the structural pillar 7 arranged on the upper surface 11a of the filled fluidized soil 11 is the fluidized soil 11 between the upper surface 2a of the existing pressure plate 2 and the lower end of the structural pillar 7. It is transmitted to the existing pressure plate 2 in a state of being dispersed in a plane via the above. The axial force of the structural pillar 7 arranged at the top end 3a of the existing foundation beam 3 is transmitted to the existing pressure plate 2 via the existing foundation beam 3.
Each of the structural pillars 7 is fixed to the new foundation 51 of the new underground structure 50, which is later constructed above the upper surface 11a of the fluidized soil 11 and the top end 3a of the existing foundation beam 3. Therefore, each structural Shinbashira 7 is supported by the ground improvement body 13 which is a support portion below the existing pressure plate 2 via the existing pressure plate 2 below the planned installation location of the new foundation 51.

As described above, by distributing the axial force of the structural pillar 7 in a plane through the fluidized soil 11 filled in the existing foundation pit space 6, the existing pressure resistance plate 2 is avoided to be destroyed. The structure pillar 7 can be supported by the ground improvement body 13 below the board 2. In addition, the filling height of the fluidized soil 11 for planarly dispersing the axial force of the structural pillar 7 is secured by utilizing the difference in the installation level between the new foundation 51 to be constructed later and the existing pressure plate 2. be able to.

Next, a method of constructing the retaining wall structure in the reverse striking method for constructing the retaining wall structure using the existing underground outer wall 4 left on the site of the demolition will be described with reference to FIGS. 1 to 4.
As shown in FIG. 1, the method of constructing the retaining wall structure is as follows: an existing underground outer wall reinforcing step for reinforcing the existing underground outer wall 4, and a guide wall with a space inside the existing underground outer wall 4 as shown in FIG. Filling with filler 23 to fill the space (hereinafter referred to as filling space) 21 between the existing underground outer wall 4 and the guide wall 20 as shown in the guide wall construction step for constructing 20 and FIG. As shown in FIG. 4, the process includes a new underground structure construction step of constructing a new underground structure 50 including a new underground outer wall 52 integrated with the inner surface 20a of the guide wall 20 by a reverse striking method.

[Existing underground outer wall reinforcement process]
As shown in FIG. 1, a pillar-shaped reinforced concrete material that protrudes in a direction orthogonal to the inner surface 4a of the existing underground outer wall 4 at the center position between the existing pillars 14 adjacent to each other on the inner surface 4a of the existing underground outer wall 4. Build a buttress 22. By reinforcing the existing underground outer wall 4 with this pillar-shaped buttress 22, the bending and shearing strength of the existing underground outer wall 4 can be increased, so that the resistance to the horizontal force (earth pressure) of the retaining wall structure using the existing underground outer wall 4 can be increased. You can improve your strength.

[Guide wall construction process]
As shown in FIG. 2, a filling space 21 is provided at a portion vertically opposed to the existing floor slab 5 on the upper floor and the existing floor slab 5 on the lower floor, and between the inner surface 4a of the existing underground outer wall 4. A guide wall 20 made of reinforced concrete and having a predetermined thickness (for example, 150 mm) is constructed at the provided inner position.
Further, the guide wall 20 is constructed at a position where a tension force is applied from the inside at the reverse striking method construction site of the new underground structure 50 which is later constructed by the counter striking method. Specifically, as shown in FIG. 5, the position of the inner surface 20a of the guide wall 20 is set to the design outer surface position 52a of the new underground outer wall 52, which is the construction site of the reverse striking method of the new underground structure 50 to be constructed later. ing.

In the guide wall 20 construction process, a part of the guide wall construction portion in the existing floor slab 5 on the upper floor and the existing floor slab 5 on the lower floor is removed. Reinforcing bars arranged on the guide wall 20 are passed through the removed part of the existing floor slab 5 on the upper floor and the removed part of the existing floor slab 5 on the lower floor. The inner formwork and the outer formwork are arranged along the inner surface forming position and the outer surface forming position of the guide wall 20. After fixing the position of the inner formwork and the position of the outer formwork with a separator, concrete is placed between the inner formwork and the outer formwork to construct a guide wall 20 integrated with the existing floor slab 5.
The construction process of the guide wall 20 is sequentially carried out from B1 on the first basement floor to B5 on the fifth basement floor.

In the above-mentioned construction process of the guide wall 20, a part of the guide wall construction part in the existing floor slab 5 on the upper floor and the existing floor slab 5 on the lower floor is removed, and the guide wall 20 made of reinforced concrete is passed through the removed part through a reinforcing bar. Since it is constructed, the guide wall 20 can be integrated with the existing floor slab 5 on the upper floor and the existing floor slab 5 on the lower floor. As a result, it is possible to improve the safety of the guide wall 20 against horizontal force (shearing) and improve the position holding performance.

[Filler filling process]
As shown in FIG. 3, the filling space 21 between the existing underground outer wall 4 and the guide wall 20 is filled with the filler 23, and a retaining wall structure composed of the existing underground outer wall 4, the filler 23 and the guide wall 20 is constructed. ..
The filler 23 is a fluidized soil obtained by adding a solidifying material such as cement to mud such as muddy water or construction sludge and kneading it, and particularly, a low-standard fluidized soil having relatively high fluidity and low strength (for example,). Compressive strength of about 3 N / mm ² ) is used. As the filler 23, various materials such as demolition waste, construction-generated soil, concrete, cement milk, and fluidized soil can be used.

As described above, since it is possible to construct a retaining wall structure in which the existing underground outer wall 4, the filler 23, and the guide wall 20 are integrated, the new underground outer wall that is the construction site of the reverse striking method of the new underground structure 50. By acting 52 as a girder, it is possible to improve the resistance to the horizontal force (earth pressure) of the retaining wall structure using the existing underground outer wall 4. Moreover, the construction cost can be reduced as compared with the case where the entire retaining wall structure including the existing underground outer wall 4, the filler 23, and the guide wall 20 is made of reinforced concrete or the like.

Before performing the filler filling step described above, as shown in FIG. 3, each guide wall 20 of the first basement floor B1 to the fourth basement floor B4 is filled with the building internal space surrounded by the inner surface 20a of the guide wall 20. A wall opening 25 for filling work that communicates with the space 21 is formed. Further, in each existing floor slab 5 from F1 on the first floor above ground to B4 on the fourth floor below ground, and in the intermediate portion between the outer surface 20b of the guide wall 20 and the inner surface 4a of the existing underground outer wall 4, the filling space 21 on the upper floor side is provided. A floor opening 26 for filling work is formed so as to communicate with the filling space 21 on the lower floor side.
A tank 41 for storing fluidized soil supplied from an agitator truck (mixer truck) 40 is placed on the existing floor slab 5 on the first floor above the ground, and a pump pipe 43 is connected to the pump 42 of the tank 41. .. Further, in order to dispose the pumping pipe 43 up to the wall opening 25 formed in each guide wall 20 of the 1st basement floor B1 to the 4th basement floor B4, the internal space of the building in the 1st basement floor B1 to the 3rd basement floor B3. Each existing floor slab 5 on the side is formed with a pipe insertion opening 27 through which the pressure feed pipe 43 can be inserted from above and below.

Then, as shown in FIG. 3, when the filling space 21 between the existing underground outer wall 4 and the guide wall 20 on the 5th basement floor B5 is filled with fluidized soil, the 1st basement floor B1 to the 3rd basement floor B3 After inserting the pumping pipe 43 into the pipe insertion opening 27 formed in each of the existing floor slabs 5, the tip of the pumping pipe 43 is inserted from the wall opening 25 of the guide wall 20 on the 4th basement floor B4 to the same floor. It is inserted into the floor opening 26 of the existing floor slab 5, and the discharge port of the pumping pipe 43 faces the filling space 21 of the lower 5th basement floor B5. In this state, the pressure pump 42 is driven to fill the fluidized soil in the tank 41 into the filling space 21 of the B5 on the 5th basement floor in a drop-in manner.
When the filling space 21 of the 5th basement floor B5 is completely filled with the fluidized soil, the fluidized soil is filled from the floor opening 26 of the existing floor slab 5 of the 4th basement floor B4 to the filling space 21 of the 4th basement floor B4. Since it overflows inside, it can be surely and easily confirmed that the inside of the filling space 21 of the B5 on the 5th basement floor is filled with the fluidized soil.

Next, the pumping pipe 43 is pulled out from the wall opening 25 of the guide wall 20 on the 4th basement floor B4, and the wall opening 25 of the guide wall 20 on this floor is closed. The tip of the pumped pipe 43 is inserted from the wall opening 25 of the guide wall 20 on the third basement floor B3 into the floor opening 26 of the existing floor slab 5 on the same floor, and the discharge port of the pump pipe 43 is placed on the lower floor. It faces the filling space 21 of B4 on the 4th basement floor. In this state, the pressure pump 42 is driven to fill the fluidized soil in the tank 41 into the filling space 21 of the B4 on the 4th basement floor in a drop-in manner.
The above procedure is repeated to fill each filling space 21 from the 5th basement floor B5 to the 2nd basement floor B2 with fluidized soil.

When filling the filling space 21 of the B1 on the first basement floor with fluidized soil, the tip of the pumping pipe 43 is inserted into the floor opening 26 formed in the existing floor slab 5 on the first floor above ground. The discharge port of the pumping pipe 43 faces the filling space 21 of the lower basement floor B1. In this state, the pressure pump 42 is driven to fill the fluidized soil in the tank 41 into the filling space 21 of the B1 on the first basement floor in a drop-in manner.

As described above, the filling space 21 of the 5th basement floor B5 to the 1st basement floor B1 is filled with fluidized soil. By hardening the filled fluidized soil, a retaining wall structure in which the existing underground outer wall 4, the fluidized soil, and the guide wall 20 are integrated is constructed.

[New underground structure construction process]
Since the position of the inner surface 20a of each guide wall 20 of the first basement floor B1 to the fourth basement floor B4 is set to the design outer surface position 52a of the new underground outer wall 52 of the new underground structure 50, the first basement floor B1 to the basement 4 In constructing the new underground outer wall 52 on the floor B4, the inner surface 20a of each guide wall 20 from the first basement floor B1 to the fourth basement floor B4 is used as an outer mold.
In the new underground structure construction process, the new underground structure 50 of the first basement floor B1 including the new underground outer wall 52, the new beam 53, the new floor slab 54, etc. is constructed while removing the existing underground structure of the first basement floor B1. ..
For the construction of the new underground outer wall 52, reinforcement is arranged in the construction area of the new underground outer wall 52 on the inner surface 20a side of the guide wall 20 of the first basement floor B1, and the inner formwork is arranged along the design inner surface position 52b of the new underground outer wall 52. Then, the inner mold is held in position by the separator provided on each guide wall 20. Concrete is placed between the inner formwork and the inner surface 20a of the guide wall 20.
The above-mentioned new underground structure construction process is sequentially carried out downward from B1 on the first basement floor to B4 on the fourth basement floor.

Then, when constructing the new underground outer wall 52 by the reverse casting method using the guide wall 20 as the outer formwork, the inner surface position of the guide wall 20 is at the design outer surface position 52a of the new underground outer wall 52, so that the thickness of the new underground outer wall 52 Does not need to be larger than necessary. Therefore, the amount of concrete for the main installation can be reduced. Furthermore, the length of the separator that holds the position of the inner formwork can be shortened to the thickness of the new underground outer wall 52, improving the position holding performance of the inner formwork and the safety of construction, and reducing the construction cost of the separator. Can be.

In the existing 5th basement floor B5, the new foundation 51 of the new underground structure 50 is constructed in a state of being integrated with the upper surface 11a of the fluidized soil 11 and the top end 3a of the existing foundation beam 3.

[Other embodiments]
(1) In the above-described embodiment, in the existing underground outer wall reinforcing step, the direction is orthogonal to the inner surface 4a of the existing underground outer wall 4 at the center position between the existing pillars 14 adjacent to the inner surface 4a of the existing underground outer wall 4. A pillar-shaped buttress 22 is constructed so as to project to the above, but instead of this buttress 22, the entire inner surface 4a of the existing underground outer wall 4 may be thickly increased.

(2) In the above-described embodiment, the buttress 22 is constructed on the inner surface of the existing underground outer wall 4 to reinforce the existing underground outer wall 4, but the existing underground outer wall reinforcing step is omitted. The filling space 21 between the existing underground outer wall 4 and the guide wall 20 may be filled with the filler 23 to construct a retaining wall structure composed of the existing underground outer wall 4, the filler 23 and the guide wall 20.

4 Existing underground outer wall 4a Inner surface 20 Guide wall 21 Space (filling space)
22 Buttress 23 Filler 25 Wall opening 26 Floor opening 50 New underground structure 52 Reverse striking method construction site (new underground outer wall)

Claims (5)

A tension force is applied from the inside at the position where a space is provided between the inside of the existing underground outer wall and the inner surface of the existing underground outer wall, and at the reverse-strike method construction site of the new underground structure to be constructed later by the reverse-strike method. The guide wall construction process to build the guide wall at the position to be acted on,
The space between the existing underground outer wall and the guide wall is filled with a filler, and a filler filling step of constructing a retaining wall structure including the existing underground outer wall, the filler and the guide wall is provided .
In the guide wall construction step, construction of a retaining wall structure in a reverse striking method in which the upper end and the lower end of the guide wall are integrated with the existing floor slab on the upper floor side and the existing floor slab on the lower floor side. Method. In the guide wall construction step, concrete is poured into the guide wall construction portion of the existing floor slab with the reinforcing bars arranged on the guide wall passed through, and the guide wall is integrated with the existing floor slab. A method for constructing a retaining wall structure in the reverse striking method according to claim 1. The retaining wall structure in the reverse striking method according to claim 1 or 2, wherein the guide wall is constructed at the design outer surface position of the reverse striking method construction site of the new underground structure to be constructed later in the guide wall construction step. How to build. A tension force is applied from the inside at the position where a space is provided between the inside of the existing underground outer wall and the inner surface of the existing underground outer wall, and at the reverse-strike method construction site of the new underground structure to be constructed later by the reverse-strike method. The guide wall construction process to build the guide wall at the position to be acted on,
The space between the existing underground outer wall and the guide wall is filled with a filler, and a filler filling step of constructing a retaining wall structure including the existing underground outer wall, the filler and the guide wall is provided.
In the filler filling step, a wall opening is formed in the guide wall and a floor opening is formed in the existing underground slab between the guide wall and the existing underground outer wall before the filler filling step is performed. A method for constructing a retaining wall structure in a reverse striking method in which a filler is dropped into the space on the lower floor side from the inside of the guide wall on the upper floor side through the wall opening and the floor opening. The method for constructing a retaining wall structure in the reverse striking method according to any one of claims 1 to 4, wherein fluidized soil is used as the filler.

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