JP2017115503A - Construction method of earth retainer wall and earth retainer wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction method of an earth retainer wall for a new skeleton and the earth retainer wall by constructing an earth retainer wall main body directly below the underground outer wall of an existing building.SOLUTION: There is provided a construction method of an earth retainer wall, which comprises the following steps. A plurality of longitudinal through holes 16 are formed on an outer wall B1 of an existing building or a skeleton part B2 near the outer wall in a lateral width direction of the outer wall surface. An improvement body successive to the lower side of an outer wall part 12 is constructed by high-pressure jet stirring via the through holes onto soil just below the outer wall part formed by the outer wall B1 and the skeleton part B2 near the outer wall. Through the through holes 16, a lower half part of a core material is embedded into the improvement body and an upper half part of the core material 24 is engaged onto the outer wall part 12. In addition, an earth retainer wall 10 is constructed with an earth retainer wall main body 20 and the outer wall part 12 connected via the core material 24.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for constructing a retaining wall and a retaining wall.

  It is known that when a new building is built at a location where an existing building is installed, instead of dismantling and removing the entire existing building, the dismantling work is performed while leaving the underground outer wall of the existing building. At this time, if the root depth of the new building is deeper than the foundation bottom of the existing building, a retaining wall is required at a location deeper than the foundation bottom of the existing building.

  In such a case, conventionally, a method of constructing a retaining wall by dismantling / removing the retaining wall construction part of the existing pressure plate in the existing underground outer wall using a lock auger or the like is used. (Patent Document 1). When the above-mentioned dismantling work is performed by continuously drilling a plurality of vertical holes in a row along the underground outer wall, a support work for connecting the inside and the outside of the vertical hole drilling location is required. .

JP 2003-293363 A

The method of Patent Document 1 has the following problems.
(1) When constructing a new underground structure, it is impossible to construct a retaining wall directly under the existing underground outer wall, so the newly constructed underground area is reduced.
(2) When drilling a pressure-resistant panel with an earth auger or the like, which hinders the construction of the retaining wall of a newly built underground frame, a large-diameter hole will be formed, so that the strength of the frame will be increased during the construction process. Is concerned about the impact of
(3) In particular, when the drilling holes are continuously formed in the pressure plate of the existing underground frame, the support work is required as described above, and the work period and the man-hour are increased.
(4) Since the retaining wall extends downward from the beam continuous with the underground outer wall and is not directly continuous with the underground outer wall, the integrity is not sufficiently maintained.

The first object of the present invention is to propose a method and a retaining wall for constructing a retaining wall for a new building by constructing a retaining wall body directly under an underground outer wall of an existing building.
The second object of the present invention is to provide a method for constructing a retaining wall for a newly-constructed frame that can reduce the obstruction removal area by performing construction by a high-pressure jet stirring method from the core hole drilled in the above-mentioned frame, Is to propose a wall.
A third object of the present invention is to provide a method for constructing a retaining wall for a newly built frame, which can reduce the number of supporting works when constructing the retaining wall main body, or can be carried out without using a supporting work. It is to propose a retaining wall.
A fourth object of the present invention is to provide a method for constructing a mountain retaining wall for a new building and a mountain retaining, which can enhance the integrity of both by introducing tension between the underground outer wall of the existing building and the mountain retaining wall main body. Is to propose a wall.

The first means is a method for constructing a retaining wall,
Drilling a plurality of vertical through holes in the outer wall of the existing building or in the vicinity of the outer wall in the width direction of the outer wall,
For the soil immediately below the outer wall portion formed by the outer wall and the casing portion near the outer wall, perform high-pressure jet agitation through the through hole, and build an improved body that continues to the lower portion of the outer wall portion,
Through the through hole, the lower half of the core material is embedded in the improved body, and the upper half of the core material is locked to the outer wall,
The mountain retaining wall is constructed by the mountain retaining wall main body and the outer wall part connected through the core material.

  This means shows a method of constructing the retaining wall shown in FIG. That is, a plurality of vertical through holes 16 are formed in the outer wall portion 12 of an existing building (see FIG. 1A), and the high pressure jet stirring pipe 30 inserted through the through holes (FIG. 1B). The improved body 20A is formed by performing high-pressure jet agitation using the reference (see (C) in the same figure), and further using the core material inserted through the through hole (see (D) in the same figure). Then, the mountain retaining wall main body and the outer wall portion formed by curing the improved body are connected to construct the mountain retaining wall. Since the improved body is formed by high-pressure jet agitation, the through hole is not enlarged, and the number of support works can be reduced (including elimination of support works). Since the improved body can be formed directly under the outer wall 12 of the existing building, the newly built underground area is not reduced.

“Connecting” the mountain retaining wall body and the outer wall part means that the binding force of the core resists an external force acting on the mountain retaining wall body and the outer wall part. It is not necessary for both to be continuously connected at the contact point. As described later, it is preferable to introduce tension into the core material, but this is not necessarily an essential requirement.
The “through-hole” may be used both for inserting the high-pressure jet agitating pipe 30 and for inserting the core member 24. Also, the through-hole for inserting the high-pressure jet agitating pipe and the through-hole for inserting the core member are respectively used. You may form (refer FIG. 8).
In addition, when providing separate through holes, the process of drilling the through hole for inserting the core material and the process of performing high pressure jet agitation through the pipe insertion hole for high pressure jet agitation do not matter. To do.

The second means is an outer wall portion formed by a housing portion near the outer wall and the outer wall of the building, and having a plurality of vertical through holes drilled in the lateral width direction of the outer wall surface,
A mountain retaining wall body constructed by improving the soil below the outer wall,
Comprising
The plurality of through holes are independent holes that are not continuous with each other,
A core for introducing prestress is provided in which the lower half is embedded in the retaining wall main body through at least a part of the through-hole, and the upper half is connected to the outer wall. Is tied up.

  This means proposes a retaining wall suitable for construction by the first means. In the case of high-pressure jet agitation, it is not necessary to make the through-holes larger than in the case of mechanical agitation. Therefore, it is easy to make the series of through-holes independent holes whose excavation ranges do not overlap each other. Moreover, this can reduce the strength reduction of the frame and reduce the number of support works (including the need for support works). Further, by introducing prestress into the core member inserted through the through hole, the retaining wall main body 20 and the outer wall portion 12 are tightly coupled. This increases the frictional force between the retaining wall body and the outer wall (see FIG. 4).

  It should be noted that the “mounting wall suitable for construction by the first means” does not mean that it is limited to the mountain retaining wall constructed by the first means. The matter described for the through hole in the first means is incorporated in this means.

The third means has the second means, and is formed by friction cutting between the through hole and the core material.

  This means proposes to provide friction cutting means 18 between the hole surface of the through hole 16 and the core member 24 as shown in FIG. Since the tension introduced into the core member 24 by this configuration is used to increase the friction force between the retaining wall main body 20 and the outer wall portion 12 without being reduced by the friction force between the core member and the through-hole, The connection between the two can be made stronger.

According to the invention relating to the first means, since high-pressure jet agitation is performed through the through hole, it is not necessary to increase the diameter of the through hole, the number of support works can be reduced, and the outer wall portion of the existing building Therefore, the mountain wall body can be constructed directly under the outer wall.
According to the second aspect of the invention, since the mountain retaining wall main body and the outer wall portion are tightly coupled by the core material for introducing prestress, the frictional resistance between the mountain retaining wall main body and the outer wall portion can be increased. Moreover, since the through hole is an independent hole, it is possible to suppress a decrease in strength of the housing.
According to the invention relating to the third means, since the friction cut means is formed between the through hole 16 and the core material, it is possible to ensure the frictional force between the retaining wall main body and the existing bottom board.

It is a longitudinal cross-sectional view of the mountain retaining wall which concerns on 1st Embodiment of this invention. It is a cross-sectional view of II-II direction of the retaining wall of FIG. It is a figure which shows the construction method of the retaining wall of FIG. 1, The figure (A) shows the step which drills a core hole in the frame of an existing building, The figure (B) shows the pipe for high-pressure injection stirring in a core hole. (C) shows the step of high-pressure injection of the curing agent through the high-pressure jet stirring pipe, and (D) shows the step of removing the high-pressure jet stirring pipe. Each of the stages of locking the core material is shown. It is explanatory drawing of the operation | work which introduce | transduces tension | tensile_strength in the step of FIG.3 (D). It is sectional drawing of the VV direction in the fragmentary figure of FIG. 3 (B). It is a figure explaining the structure and usage method of the high pressure injection stirring pipe used for construction of the retaining wall of FIG. 1, The figure (A) excavates the lower side soil by the downward injection of the high pressure injection stirring pipe. FIG. 4B shows a state in which the high-pressure jet stirring pipe is rotating and rising while being stirred around by the horizontal injection. It is a longitudinal cross-sectional view of the mountain retaining wall which concerns on 2nd Embodiment of this invention. It is a cross-sectional view of a mountain retaining wall according to a third embodiment of the present invention.

  1 to 5 show a retaining wall and a method for constructing the retaining wall according to the first embodiment of the present invention. In FIG. 1, 2 is the ground, and 4 is an excavation part. For convenience of explanation, the configuration of the retaining wall will be described.

The retaining wall 10 according to the present invention includes an outer wall portion 12 and a retaining wall body 20 of an existing building.
In this specification, the outer wall portion 12 refers to the outer wall B1 of the frame B of the existing building and the frame portion B2 near the outer wall. As the latter, for example, the base of the load bearing board B3 and the floor slab shown in FIG.

A plurality of through holes 16 are provided vertically in the outer wall portion 12 and are arranged at equal intervals in the lateral width direction of the outer wall portion as shown in FIG.
These through holes 16 are drilled as core holes prior to the dismantling operation of the existing building.
As shown in FIG. 2, the through hole 16 of the present invention is an independent hole in which the drilled portions do not overlap each other, and therefore, the degree to which the strength of the housing body is reduced is small.
In addition, the through-hole 16 of the present embodiment is used both for inserting a high-pressure jet stirring pipe 30 and for inserting a core member 24, which will be described later. The high-pressure jet agitation method is a method in which an ultra-high-pressure hardener is spun into the ground while rotating with compressed air, and a cylindrical hardened body is formed in the ground while excavating the ground. Compared with the method of excavating the ground, it is not necessary to excavate a large-diameter hole.
The diameter of the through hole 16 of this embodiment is usually about 200 mm.
And in this embodiment, the space | interval of through-holes is taken to such an extent that it is not necessary to connect the inner side and the outer side of the drilling location of a through-hole by support work. Although the magnitude | size of the space | interval changes with cases, a space | interval of about 1 m can be taken as a suitable example.
In addition, the through-hole 16 of the present embodiment is formed by vertically drilling a floor slab and a pressure-resistant panel on each floor in a housing part B2 near the outer wall of an existing building.
Friction cut means 18 is formed in the hole surface of the lowest through hole 16 provided in the pressure platen. The friction cut means 18 can be formed of a sheet having a low friction coefficient.

  As shown in FIG. 1, the mountain retaining wall body 20 is formed directly below the outer wall portion 12. The mountain retaining wall main body 20 is formed by a cylindrical improvement body 20A that is subjected to a high-pressure jet stirring method through the above-described through-holes 16 and centered on each through-hole as viewed from above. The diameters of these cylindrical bodies are larger than the diameter of the through hole and are connected to each other to form a wall. The improved body also has an extension 21 extending into the bottom through-hole 16.

  After the improved body 20A is hardened, at least the inner casing part from the outer wall part 12 is disassembled, and the excavation part 4 is formed by excavating the ground below the casing part.

  The core member 24 is a stress material that connects the outer wall portion 12 and the retaining wall body 20, and the lower end portion thereof is inserted and fixed before the retaining wall body 20 is cured. Moreover, the upper end part is latched by the latching tool 26 installed in the appropriate place of the outer wall part 12 (on the through-hole 16 drilled in the load bearing board in the illustrated example).

  The shape of the core member 24 can be set to an appropriate shape (for example, a shape provided with an annular groove / screw groove-like unevenness) in order to improve the fixing force with the improved body. Further, when the fixing force is insufficient with only the core material in the retaining wall main body 20, the resistance portion 28 attached or attached to the outside of the core material 24 can be attached. As an example of the resistance portion, a mechanical fixing member is cited. As an example of the mechanical fixing member, a member having an appropriate shape (for example, a cylindrical shape) having a core material insertion hole and having a required resistance can be used. A screw structure that meshes with each other is formed on the inner surface of the core material insertion hole and the outer surface of the core material.

  In the present embodiment, the core member 24 uses a reinforcing bar material suitable for introducing a tension, and after the lower end portion of the core member 24 is fixed to the improved body 20A, the core member 24 is pulled up by the above-described locking tool 26 to apply tension. I have to.

FIG. 3 shows a method for constructing a retaining wall according to the present invention.
As shown in FIG. 3A, a through hole 16 is formed in the outer wall 12 of an existing building. Since the through hole 16 is a relatively small-diameter independent hole, no support work is required.
Next, as shown in FIG. 3 (B), the pipe 30 for high-pressure jet agitation is inserted into the ground below the outer wall portion 12 through the through-holes 16 through the forming machine S installed on the slab, and FIG. ), The curing agent is ejected from the pipe to form the improved body 20A. Although not shown in both figures, the core member 24 is inserted into the ground below the outer wall portion 12 from the lowermost through hole 16.
An injection unit 32 is attached to the lower end of the above-described high-pressure injection agitation pipe 30, and the injection unit 32 has a first injection port 32 </ b> A downward and a second injection port 32 </ b> B in the horizontal direction. The high-pressure jet agitation pipe 30 is supported by the generator S in such a manner that it can be raised and lowered and rotated.
Then, as shown in FIG. 6 (A), the high-pressure jet agitation pipe 30 is lowered while jetting downward drilling water from the first jet port 32A. Thereby, the vertical hole part 6 is formed in the ground. After the vertical hole 6 having the required length is formed, the high-pressure jet agitation pipe is rotated and pulled up while jetting the curing agent from the second jet port 32B. Thereby, the soil around the vertical hole is excavated and stirred, and mixed with the hardener. Thereby, the cured body 20A is formed. As described above, as shown in FIG. 6B, the second injection port 32B gradually moves to the outer wall lower surface 14 to form the cured body 20A. Incidentally, in the known injection part 32, the means for switching the injection port from the lower first injection port 32A to the horizontal second injection port 32B is implemented by attaching and detaching a water stop ball (not shown) in the injection port 32. The
Then, the restraint jet stirring pipe is removed, and the lower half of the core member 24 is inserted into the improved body 20A. After that, the improved body is cured.
Then, after hardening to the extent that the improved body 20A exists, the locking member 26 shown in FIG.
After that, the building housing part inside the two-dot chain line a shown in FIG. 3D and the outer wall part outside the two parts are dismantled, and the ground below the housing part is further excavated to form the excavation part 4. To do.

In FIG. 4, the effect | action of the tension | tensile_strength introduction to the core material 24 is shown. That is, the core member 24 fixed to the main body 10 is tightened as indicated by an arrow in the drawing, so that the upper surface 22 of the main wall 20 and the lower surface 14 of the outer wall portion 12 are strongly pressed against each other. For this reason, the frictional force between both surfaces increases, and a sufficient resistance against lateral external force is exhibited.
Since the through hole 16 has a friction cut, the load loss due to friction between the extended portion 21 of the improved body 20A and the through hole 16 can be reduced, and the above tightening force is fastened. This can be sufficiently utilized as a pressure contact force between the upper surface 22 of the wall body 20 and the lower surface 14 of the outer wall portion 12. Thereby, the integrity of the improved body 20A and the outer wall portion 12 is increased.
Here, the term “integration” mainly means that the pressure contact force between the improved body and the outer wall portion is increased, and a trial calculation is performed so that a predetermined friction force can be obtained only by the pressure contact force. However, it is considered that the improved body 20 </ b> A is pressed against the lower surface of the outer wall portion 12 and hardens in a shape that is compatible with the shape of the lower surface of the outer wall portion 12, thereby producing an action such as “meshing”.

Here, the above-described friction mechanism is estimated.
Resist with friction generated by tightening the reinforcing bar against external load.
Degree of allowable adhesion stress: 0.1 Fc = 0.2 N / mm ²
Load from outside: Q: 23.0 t / m
The introduction axial force necessary to withstand the shearing force Q is assumed to include two reinforcing bars per meter.
N = Q / (2 × μ) = 230 kN
If we consider inserting a reinforcing bar 8m below the bottom plate, 230020 / (8000 × 160) = 0.18N / mm ² <0.2N / mm ²
If a numerical value of 0.2 N / mm ² is adopted with a margin, the introduced torque T at that time is T = k × d × N = 0.2 × 0.051 × 230 = 2.3 kN · m
From the above, it can be seen that sufficient stability can be obtained.

  According to the retaining wall and its construction method of the present invention, the retaining wall body 20 is formed directly under the outer wall of the existing building using the high-pressure jet agitation method, so that the site area of the new building is not too narrow, Since the high-pressure jet agitation method does not require a large-diameter through-hole, reinforcement by support work can be reduced, and the construction period and man-hours can be reduced.

  Hereinafter, other embodiments of the present invention will be described. In these descriptions, the description of the same configuration as that of the first embodiment is omitted.

  FIG. 7 is a longitudinal sectional view showing a mountain retaining wall according to the second embodiment of the present invention. In this embodiment, a long through hole 16 is provided vertically on the outer wall B1 of the existing building. A mechanical fixing member 28 is provided at the lower end of the core member 16.

FIG. 8 is a longitudinal sectional view showing a mountain retaining wall according to a third embodiment of the present invention.
In this embodiment, a first through hole 16A into which the core member 24 is inserted and a second through hole 16B into which the high-pressure jet stirring pipe 30 is inserted are formed as the through holes, respectively.
In the illustrated example, the second through hole 16B has a larger diameter than the first through hole 16A. Further, the friction cut is applied only to the hole surface of the first through hole 16A.
Unlike the illustrated example, the second through-hole 16B may be used both for inserting the core member 24 and for inserting the high-pressure jet agitating pipe 30.

  Note that the embodiment of the present specification merely shows a preferred embodiment, and does not prevent the contents from being appropriately changed unless the spirit of the present invention is violated.

DESCRIPTION OF SYMBOLS 2 ... Ground 4 ... Excavation part 6 ... Vertical hole part 10 ... Mountain retaining wall 12 ... Outer wall part 14 ... Outer wall part lower surface 16 ... Through-hole 16A ... 1st through-hole 16B ... 2nd through-hole 18 ... Friction cut means 20 ... Mountain retaining body 20A ... Improved body 21 ... Extension part 22 ... Top surface of mountain retaining body
24 ... Core material 26 ... Locking tool 28 ... Resistance part 30 ... Pipe for high-pressure injection stirring 32 ... Injection part 32A ... First injection hole
B ... Body of the existing building B1 ... Outer wall of the existing building B2 ... Body part near the outer wall B3 ... Strengthening panel S ... Building machine

Claims (3)

A method for constructing a retaining wall,
Drilling a plurality of vertical through holes in the outer wall of the existing building or in the vicinity of the outer wall in the width direction of the outer wall,
For the soil immediately below the outer wall portion formed by the outer wall and the casing portion near the outer wall, perform high-pressure jet agitation through the through hole, and build an improved body that continues to the lower portion of the outer wall portion,
Through the through hole, the lower half of the core material is embedded in the improved body, and the upper half of the core material is locked to the outer wall,
A method of constructing a retaining wall with a retaining wall main body and an outer wall connected via a core material. An outer wall portion formed of a housing portion near the outer wall and the outer wall of the building, and having a plurality of vertical through holes drilled in a lateral width direction of the outer wall surface;
A mountain retaining wall body constructed by improving the soil below the outer wall,
Comprising
The plurality of through holes are independent holes that are not continuous with each other,
A core for introducing prestress is provided in which the lower half is embedded in the retaining wall main body through at least a part of the through-hole, and the upper half is connected to the outer wall. A mountain retaining wall that is tied together. The mountain retaining wall according to claim 2, wherein a friction cut between the through hole and the core material is performed.