JPH0138927B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for connecting underground walls, and more specifically, when connecting underground walls constructed by pouring concrete in a step-by-step manner to form a continuous underground wall.
This article relates to a method for connecting underground walls that performs special water-stopping construction between adjacent underground walls.

When constructing a diaphragm wall of the type described above,
After drilling the first hole, a blocking means is provided at the end of the hole;
For example, an interlocking pipe is built, and concrete that is to become an underground wall is placed in the first hole. Thereafter, after the concrete has hardened, the interlocking pipe is pulled out, a second hole is drilled to extend the first hole on the end side, and the same operation is repeated.

However, since the hole drilled as described above is filled with a stabilizing liquid consisting of muddy water to prevent the collapse of the ground, the end surface of the concrete poured in the first hole on the second hole side A mud film adheres to the surface. Moreover, when pouring concrete into the second hole, slime may accumulate near the end face, or avalanche may occur in which the concrete that has spewed out from the concrete pouring pipe and formed a mountain around it flows to a lower part. As a result, voids without concrete may be created near the end faces, resulting in weak spots in the connecting parts of the underground walls including the end faces, resulting in unavoidable defects in water-stopping properties.

Therefore, it is an object of the present invention to prevent the above-mentioned problems from occurring at the connection between the previously constructed underground wall and the subsequently constructed underground wall, without stopping the concrete from being placed. The object of the present invention is to provide a method for connecting underground walls that can significantly improve water-stopping performance through water construction.

The present invention is a method for connecting an underground wall constructed by pouring concrete in a step-by-step manner, and includes a holding portion having a concave shape on the outer peripheral surface at the end of a first hole; erecting a blocking means held by a soft member such that the soft member is positioned between the hole wall surfaces in the width direction of the first hole; pouring concrete into the first hole; pulling out the blocking means from the first hole with the soft member remaining after hardening; a second hole being drilled at the end side of the first hole to extend the first hole; pouring concrete into the concrete, after the concrete has hardened, drilling a hole from the soft member to the surrounding concrete using the boundary surface of the concrete surrounding the soft member with the soft member as a guide surface for a bit; including filling with mortar.

Another feature of the present invention is that a blocking means is built into the end of the first hole, a first joint box is built along the blocking means, and a concave holding portion is provided on the outer peripheral surface. and placing a second joint box holding a soft member in the holding portion along the first joint box such that the soft member is located on the hole wall side in the width direction of the first hole. pouring concrete into the first hole; pulling out the blocking means from the first hole after the concrete has hardened; pulling out the second joint box from the first hole while leaving the soft member in the space created by pulling out the second joint box; erecting a spacer box in contact with the box and the concrete; from a second hole drilled on the end side of the first hole to extend the first hole; After pulling out the joint box, concrete is poured into the second hole, and after the concrete has hardened, the interface between the concrete surrounding the soft member and the soft member is used as a guide surface for the bit to be removed from the soft member. It involves drilling a hole through the surrounding concrete and filling the hole with mortar.

Still other features of the invention include building a blocking means at the end of the first hole, building a concrete block having a through hole along the blocking means, and placing concrete in the first hole. pouring, and pulling the blocking means out of the first hole after the concrete has hardened; and drilling a second hole at the end of the first hole to extend the first hole.
After the concrete has hardened, the concrete is poured into the first and second holes from the concrete block using the inner peripheral surface of the through hole of the concrete block as a guide surface for the bit. and filling the hole with mortar.

Embodiments of the present invention will be described below with reference to the drawings.

In the connection method of the present invention, a blocking means, which will be described later, is installed at the end of the first hole 10 in which concrete is placed in advance. Prior to this, a first hole 10 is excavated (FIG. 1). In terms of work efficiency, it is preferable to excavate the first hole 10 using a digging tool such as a clamshell type bucket. To do this, the preliminary boring hole 12 is bored with a reversing machine with good vertical accuracy, and the semi-cylindrical ground surface 14 is used as a guide for the bucket.
In addition, when the soil is hard or rocky, a plurality of hollow boring holes 16 are made to loosen the soil in advance to facilitate bucket excavation. This hollow boring is used for soft rock (compressive strength less than 500Kg/ ^cm2 ) with a rock auger, hard rock (compressive strength 500Kg/cm2 or less).
Kg/cm ² or more), use a reverse machine. The area excavated with a bucket is filled with a stabilizing solution consisting of muddy water to prevent the ground from collapsing. After drilling the first hole, the bottom of the hole is roughened and slime is treated.

At the end of the first hole 10, in the illustrated example, at the position of the preceding boring hole 12, an interlocking pipe 18, which is a blocking means, is built in the manner described later (second
figure). The blocking means may be of any type as long as it prevents the flow of concrete poured into the first hole 10.
In addition to the interlocking pipe shown in the illustrated example, an interlocking box having a rectangular cross section may be used as appropriate.

A concave holding portion 20 is provided on the outer circumferential surface 19 of the interlocking pipe 18 along the entire length thereof. Prior to installing the interlocking pipe 18, a soft member 22 made of expanded polystyrene is held in this holding part 20. For holding, the soft member 22 is pushed into the holding part 20 to deform it, and in addition to being held by the holding part 20, a small amount of adhesive is applied intermittently in the axial direction of the holding part 20, or it is pasted intermittently with adhesive tape. Or by tying it with thin, weak wire. Regardless of the holding form, as will be described later, the soft member 22
When the part 24 protruding from the outer peripheral surface 19 of the interlocking pipe is surrounded by concrete poured into the first hole 10, the holding force of the concrete after concrete hardening is greater than the holding force of the holding part 20. Instead, the soft member 22 is retained in the concrete so that the interlocking pipe 18 can be pulled out. Soft member 2
2 is made of a material softer than hardened concrete. For example, in addition to the Styrofoam, wood,
Rubber, etc.

In the illustrated example, the cross section of the holding portion 20 is arcuate, and the cross section of the soft member 22 is circular. The cross-sectional area of the portion 24 of the soft member 22 protruding from the outer peripheral surface 19 of the interlocking pipe 18 is larger than the cross-sectional area of the portion 25 held by the holding portion 20. As a result, as will be described later, when concrete is poured into the first hole 10 and after the concrete hardens, the soft member 22 remains in the concrete and the interlocking pipe 18 is pulled out. The portion 25 of the soft member 22 that protrudes toward the hole is reduced, which is preferable because there is less possibility of damaging the soft member 22 when drilling the second hole. The cross section of the soft member 22 may be rectangular, elliptical, etc. other than circular, and in this case, the cross section of the holding part 20 matches the cross-sectional shape of the soft member and can hold a portion of the soft member along the axis. It is the shape.

The interlocking pipe 18 holding the soft member 22 is held in place so that the portion 24 of the soft member 22 protruding from the outer peripheral surface 19 of the interlocking pipe is the first
The soft member 22 is placed between the hole wall surfaces 26 and 27 in the width direction of the hole 10, and is built at the end of the hole 10 so that the soft member 22 is vertical (FIG. 2).

After installing interlocking pipe 18,
A reinforcing bar basket 28 is inserted into the first hole 10, and a tremie pipe 30, which is a concrete pouring pipe, is installed (the third
figure). Using this tremie tube 30, the first hole 1
After the fine particles precipitated in the concrete are slimed by an air lift, concrete is poured into the stabilizing liquid using a tremie pipe 30. After the concrete hardens, the interlocking pipe 18 is pulled out with the soft member 22 remaining in the concrete. After the concrete has hardened is the period when the concrete does not flow even if the interlocking pipe 18 is pulled out and is self-retained in the cast shape, and the interlocking pipe 18 is easy to pull out. This was several hours after the installation. The concrete hardens and becomes an underground wall 32.

Next, in order to extend the first hole on the end side of the first hole 10, the second hole 34 was excavated in the same procedure as the first hole 10 (FIG. 4), and the bottom was roughened and treated with slime. After that, the reinforcing bar cage 28 is inserted into the second hole 34, and the tremie tube 30 is installed (FIG. 5). After sliming fine particles with this tremie tube 30,
Concrete is poured into the second hole 34 (including the first hole after the interlocking pipe 18 has been pulled out). This concrete hardens and becomes an underground wall 36.

After pouring concrete into the second hole 34, an underground wall 32 constructed from the concrete placed first and an underground wall constructed from the concrete placed subsequently. After the connecting portion 38 with the soft member 36 has shrunk, a hole is drilled from the soft member 22 to the surrounding concrete using the interface 40 of the concrete surrounding the soft member with the soft member as a guide surface for the bit.

Preferably, the holes are made using a hole expanding bit 42 shown in FIG. The hole expanding bit 42 has a tip bit 46 having the same diameter as the core tube at the distal end of the core tube 44, which has an outer diameter slightly smaller than or substantially equal to the outer diameter of the soft member 22, and a wing bit 48 at the rear end. The soft member 22 is pierced by a tip bit 46, respectively. The wing bits 48 are formed in a shape that widens toward the rear end, and are attached to the core tube 44 by welding, for example, at intervals of 90° in the circumferential direction.
The hole expanding bit 42 is attached to the boring machine,
be rotated.

When the tip bit 46 perforates the soft member 22 and enters the soft member, the outer peripheral surface of the core tube 44 is guided by the concrete boundary surface 40 of the underground wall surrounding the soft member 22, and the hole expansion bit 42 gradually enters in the direction in which the soft member 22 extends. When the wing bit 48 reaches the concrete boundary surface 40, the concrete around the concrete boundary surface 40 is scraped away and expanded, and a hole 41 extending from the soft member to the surrounding concrete is bored (FIG. 6). With this hole expansion,
The mud film adhering to the expanded portion of the connecting portion 38 scrapes off weak spots.

After drilling, the hole 41 is subjected to a water permeability test (Lugeon test), and the state of the cracks and the presence or absence of weak points are confirmed based on the water permeability of the hole 41. Visual confirmation using borehole television is also possible instead of a water permeability test. After the water permeability test, grouting is performed as necessary to strengthen cracks and weak areas to improve water-stopping properties. However, since the hole 41 formed as described above is located at the connecting part 38 between the concrete placed previously and the concrete placed subsequently, there is always a gap in the connecting part 38 itself. . Therefore, first, a double pipe with a perforated strainer pipe as the outer pipe is inserted into the hole 41, and then gain, which is a mixture of mortar and bentonite, is injected between the outer pipe and the inner pipe to widen the crack at the connection part 38. After solidifying to prevent water from leaking through the cracks, patch grouting is performed at designated locations.

After the grouting, the holes 41 are filled with expanding mortar or non-shrinking mortar 42 (FIG. 6).
The same operation is then performed to connect adjacent underground walls, and a continuous underground wall is constructed.

8 to 12 show another connection method.
The same elements as in the previous method will be described using the same reference numerals.

An interlocking pipe 18 is installed at the end of the first hole 10 drilled in the same manner as described above. The interlocking pipe 18 in this case is not subjected to any special processing. A first joint box 44 is installed along this interlocking pipe 18, and a second joint box 46 is installed along the first joint box 44 in a manner described later (FIG. 8). . In the illustrated example,
The side surface of the first joint box 44 facing the interlocking pipe 18 is formed into a concave surface 45 that is concave inward to fit the outer peripheral surface of the interlocking pipe 18. This is preferred because the concave surface 45 can be used as a guide surface for the bucket when the second hole is excavated by the clamshell bucket after the interlocking pipe 18 is pulled out.

A concave holding portion 48 is provided on the outer peripheral surface 47 of the second joint box 46, and the soft member 22 is held in this holding portion 48. The holding portion 48 holds the soft member 22 at a position that substantially bisects the cross section of the soft member.
It holds a portion 25 along the axis of the outer peripheral surface 4.
The portion 24 of the soft member protruding from the first hole 1
The second joint box 46 is inserted into the first hole 1 so that it is located between the hole wall surfaces 26 and 27 in the width direction of the hole 1.
Set it to 0. In the illustrated example, the widthwise side surface 49 of the second joint box 46 and the hole wall surfaces 26, 2
An air bag 50 is interposed between each of them and 7. This air bag is filled with compressed air and brought into close contact with the hole wall surface to prevent the concrete poured in the first hole 10 from going around toward the first joint box 44. An air hose can be used instead of an air bag.

After inserting the reinforcing bar cage 28 into the first hole 10 and installing the tremie pipe 30, slime treatment is performed and concrete is poured (FIG. 9). After concrete hardens,
The interlocking pipe 18 is pulled out, and then the second joint box 46 is pulled out with the soft member 22 remaining in the concrete (10th joint box 46).
figure). It is also possible to withdraw the second joint box 46 prior to withdrawing the interlocking pipe 18. However, in terms of ease of pulling out, it is better to pull out the interlocking pipe 18 first. Second joint box 46
The extraction is performed by removing the compressed air from the air bag 50.

A spacer box 54 is built into the space 52 created by pulling out the second joint box 46 (FIG. 11). The spacer box 54 is provided with a recess 55 which covers and protects the portion 25 of the soft member 22 which projects from the concrete into the space 52. The spacer box 54 is in contact with the side surface of the concrete 32 and the side surface of the first joint box 44, respectively,
The reaction force applied to the first joint box 44 during excavation of the second hole 34 is received.

After the second hole 34 is excavated in the same manner as described above, the first joint box 44 and spacer box 54 are pulled out, and concrete is poured in the same manner as described above (FIG. 12). after that,
At the connecting portion 38 of the underground walls 32, 36, a hole is drilled from the soft member 22 to the surrounding concrete in the same manner as described above, and after a water permeability test and grouting treatment, the hole is filled with expanding mortar or non-shrinking mortar 42.

FIGS. 13 to 16 show still another connection method.

First hole 10 drilled by the same procedure as above
An interlocking pipe 18 is erected at the end of the interlocking pipe 18, and a precast concrete block 58 is erected along this interlocking pipe 18 (FIG. 13).

The concrete block 58 has a through hole 60 in the center.
The hole wall surfaces 26, 27 of the first hole 10
It has a width between concrete block 5
The side surface facing the interlocking pipe 18 of No. 8 is formed into a concave surface 59 that is concave toward the inside and fits the interlocking pipe 18. This concave surface 59 serves as a guide surface for the clamshell bucket during the second hole drilling. In the illustrated example, the concave surface 59 is provided symmetrically with respect to the through hole 60. In this way, when erecting the concrete block 58, the installation direction can be set arbitrarily, so that work efficiency is improved. It is preferable that the thickness W of the minimum thickness portion of the concrete block 58 is set to be 50 mm or more smaller than the diameter of the hole to be drilled thereafter. In this way, later drilling becomes easier.

The concrete block 58 is built so that the axis of the through hole 58 is vertical. When the depth of the underground wall is large, a plurality of concrete blocks 58 are stacked vertically. In this case, the connecting portions between the concrete blocks 58 are formed so that they can be connected, for example, by chain pins similar to segment type male and female chuck pins in the shield construction method.

After constructing concrete block 58, the first
A reinforcing bar cage 28 is inserted into the hole 10, concrete is poured, and after the concrete hardens, the interlocking pipe 18 is pulled out (FIG. 14). After that, a second hole 34 is excavated, a reinforcing bar cage 28 is inserted, and concrete is poured. After concrete shrinks,
Using the inner peripheral surface 61 of the through hole 60 of the concrete block 58 as a guide surface for the bit, a hole 62 is drilled from the concrete block 58 to the concrete of the underground walls 32 and 36, and after a water permeability test and grouting treatment, the hole 62 is filled with expanded mortar. Or fill with non-shrinkage mortar 42. This example is particularly suitable when the depth is large.

The effects achieved by the connection method of the present invention are summarized as follows.

(b) The boundary surface of the concrete surrounding the soft member embedded in the poured concrete with the soft member, or the inner circumferential surface of the through hole of a concrete block previously provided with the through hole, is used as the guide surface for the bit. Since the bit is advanced and the hole is drilled across the concrete between the underground wall constructed beforehand and the underground wall constructed afterward, the guidance of the bit is reliable, and the drilling itself is extremely easy. In addition, by drilling, it is possible to scrape off weak areas such as the mud film of the stabilizing liquid, slime accumulation areas, and so-called junks where aggregate is exposed due to lack of mortar.

(b) The condition of cracks and weak points can be investigated and confirmed based on the water permeability obtained as a result of the water permeability test of the hole or visual confirmation using borehole television.

(c) Based on the results of water permeability tests or borehole TV visual inspection, the joints can be completely sealed by grouting cracks and weak points or by filling with expanding mortar or non-shrinking mortar without grouting. It has water-tightness close to that of the original, and can also strengthen weak areas.

(d) Since it is not necessary to install special partition steel materials or embedded objects such as H-beam steel at the joints between adjacent underground walls, it can be constructed at low cost and is excellent in terms of economy.

Based on the above-mentioned effects, the present invention connects underground walls that are constructed in stages when constructing underground continuous walls such as impermeable walls of dams, underground permanent structures, deep underground structures, etc. Particularly suitable when

[Brief explanation of drawings]

Figures 1 to 6 are sectional views showing the procedure of the first invention, Figure 7 is a front view of the hole expanding bit, and Figure 8 is a front view of the hole expanding bit.
12 to 12 are sectional views showing the procedure of the second invention, and FIGS. 13 to 16 are sectional views showing the procedure of the third invention. 10: First hole, 18: Interlocking pipe (blocking member), 20: Holding part, 22: Soft member, 26, 27: Hole wall surface, 28: Rebar cage, 30:
Tremy pipe, 32, 36: underground wall, 38: connection, 40: concrete wall, 42: mortar,
44: First joint box, 46: Second joint box, 57: Air bag, 5
2: Space, 54: Spacer block, 58: Precast concrete block, 60: Through hole.

Claims (1)

[Claims] 1. A method for connecting underground walls constructed by pouring concrete in stages in a step-by-step manner, the first hole having a concave holding portion on its outer peripheral surface at the end thereof; erecting a blocking means holding a soft member in the holding portion such that the soft member is located between the hole wall surfaces in the width direction of the first hole; and pouring concrete into the first hole. , pulling out the blocking means from the first hole with the soft member remaining after the concrete hardens, and a first hole excavated to extend the first hole at the end side of the first hole pouring concrete into the hole No. 2, and after the concrete hardens, drilling a hole extending from the soft member to the surrounding concrete using the boundary surface of the concrete surrounding the soft member with the soft member as a guide surface for the bit; , a method for connecting an underground wall, comprising filling the hole with mortar. 2. The connection method according to claim 1, wherein the holding portion is provided over the entire length of the blocking means, and the soft member has a length approximately equal to that of the blocking means. 3. The soft member held by the blocking means has a portion protruding from the outer peripheral surface of the blocking means, and the cross-sectional area of the portion is larger than the cross-sectional area of the portion held by the holding portion. Range 1 or 2
Connection method described in section. 4. A method for connecting underground walls constructed by pouring concrete in stages in stages, in which a blocking means is built at the end of the first hole, and a first joint is installed along the blocking means. A second joint box having a concave holding portion on its outer circumferential surface and holding a soft member in the holding portion is installed so that the soft member is attached to the hole wall surface in the width direction of the first hole. placing concrete along the first joint box so as to be located in between; placing concrete in the first hole; and pulling out the blocking means from the first hole after the concrete hardens. The second joint box may be pulled out from the first hole with the soft member remaining after or prior to the withdrawal of the blocking means, or the second joint box may be pulled out. erecting a spacer box that covers the soft member and contacts the first joint box and the concrete in the space formed by the flexible member; and extending the first hole at the end side of the first hole. pouring concrete into the second hole after pulling out the spacer box and the first joint box from the excavated second hole; and after the concrete hardens, the soft member of concrete surrounding the soft member; Drilling a hole from the soft member to the surrounding concrete using the interface with the bit as a guide surface for the bit,
A method for connecting an underground wall, the method comprising filling the hole with mortar. 5. The connection method according to claim 4, wherein a sealing air bag is disposed between the second joint box and the hole wall surface. 6. A method for connecting underground walls constructed by pouring concrete in stages in places, which includes constructing a blocking means at the end of the first hole, and placing a concrete block with a through hole in the blocking means. placing concrete in the first hole; pulling out the blocking means from the first hole after the concrete has hardened; and placing concrete on the end side of the first hole. pouring concrete into a second hole drilled to extend the first hole; after the concrete hardens, the concrete block is moved from the concrete block to the second hole using the inner peripheral surface of the through hole of the concrete block as a guide surface for a bit; drilling a hole across the concrete cast in the first and second holes;
A method for connecting an underground wall, the method comprising filling the hole with mortar.