JPH11269870A - Execution method of joint for underground continuous wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to surely bear concrete side pressure with a simple method in the case concrete for preceeding elements is cast when a steel plate is used for a joint, enable the reuse of a member for that purpose as well as the promotion of economical efficiency and to make it possible to manufacture the joint with high execution efficiency without requiring any casting height adjustment of concrete. SOLUTION: An execution method of a joint for an underground continuous wall is so constituted that ditches are excavated in the ground at specific intervals, concrete is cast to execute preceeding elements 1, ground between the preceeding elements 1 is excavated, concrete is cast therein to execute following elements and that the preceeding elements and following elements are continued at joint surfaces of their ends. Expansible bag bodies 9 are mounted to the outises of joint steel plates 4 arranged to the joint surfaces, the bag bodies 9 are expanded in the case concrete for the preceeding elements 1 is cast, side pressure in the case of concrete casting is borne on bedrocks 8 of the excavated ditches 2 through the bag bodies 9, and after the concrete is solidified, the bag bodies 9 are contracted to remove them from the insides of the excavated ditches 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a joint for an underground continuous wall.

[0002]

2. Description of the Related Art When constructing an underground continuous wall, trenches are excavated at intervals in the ground, concrete is poured into the excavation trench to construct a leading element, and then, a space between the leading elements is formed. A groove is excavated in the ground, and concrete is poured into the excavation groove to construct a succeeding element, and a leading wall and a trailing element are connected to each other at a joint surface at each end to construct a continuous wall.

[0003] There are various types of joints (inter-element joints) for the underground continuous wall. One example is a steel plate used for the joint surface. FIG. 9 shows a joint steel plate joint showing one example of the joint, in which a joint steel plate 4 is attached to both ends of a reinforcing steel cage 3 arranged in a digging groove 2 of a preceding element 1 and concrete 5 is cast, and is shown in FIG. Thus, the joint surface with the following element 6 becomes the joining steel plate 4.

In such a jointed steel plate joint, the leading element 1
The joint steel plate 4 receives the lateral pressure at the time of concrete casting of the steel plate 4 so that the steel plate 4 can withstand this.
Is welded to the end of the horizontal reinforcing bar, but the strength of the joint steel plate 4 having a thickness of about 6.0 mm to 9.0 mm which is usually used is not sufficient, and the joint steel plate 4 may be excessively deformed.

Therefore, as shown in FIG. 9, for example, crushed stone 7 or the like is put into the excavation groove 2 at a position outside the joint steel plate 4 so as to withstand the lateral pressure at the time of placing concrete. The injection of the crushed stone 7 is performed several meters ahead of the concrete injection while balancing the input amounts to the joints on both sides.

[0006]

As described above, the joint of the type using the joint steel plate 4 in which the crushed stone 7 is introduced as a method of supporting the lateral pressure of the concrete to be cast is used when the subsequent element 6 is excavated. Since the excavated soil of the ground is mixed with the crushed stone, it is difficult to recover and reuse the crushed stone 7 and the economic efficiency is not good.

In addition, it is necessary to gradually increase the amount of the crushed stone 7 in accordance with the height of the concrete to be cast, and it is necessary to control the height adjustment of the concrete to be poured and the crushed stone. Workability was not good.

Further, in the case of a type using a steel plate for the joint, such as a rigid joint in which a reinforcing bar or the like projects on the joint surface of the preceding element toward the succeeding element, it is necessary to protect the joint reinforcing bar when the succeeding element is constructed. Yes, it is necessary to build a protection plate and so on.

This inconvenience can be solved by using no steel plate for the joint. For example, a steel pipe (interlocking pipe) having a circular cross section is erected at the end of the preceding element as a type that does not use a steel plate, and is driven by this interlocking pipe. Some of them bear the lateral pressure of concrete, and pull out the interlocking pipe in accordance with the hardening of the poured concrete to form a space having a semicircular horizontal section and connect the elements.

[0010] However, in this interlocking pipe joint, the gap between the interlocking pipe and the ground is increased due to poor excavation accuracy and skin fall, and concrete wraps around the pipe back surface, making it difficult to excavate the following element. If the timing of pulling out the interlocking pipe is inappropriate, pulling out may not be possible.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art, and when using a steel plate for a joint, it is possible to reliably bear the concrete side pressure at the time of placing concrete in the preceding element in a simple manner. An object of the present invention is to provide a method of constructing a joint of an underground continuous wall, which can be reused to improve the economic efficiency, does not require adjustment of the concrete placement height, and has good workability.

[0012]

According to the present invention, in order to achieve the above object, firstly, trenches are dug at intervals in the ground, concrete is cast, and a preceding element is constructed. In the method of excavating the ground in between, casting concrete here and constructing the succeeding element, and connecting the preceding element and the succeeding element at the joint surface at each end of the underground continuous wall joint construction method An inflatable bag is attached to the outside of the joint steel plate provided on the joint surface, the bag is inflated when the preceding element is poured into the concrete, and the side pressure at the time of casting the concrete is applied to the excavation groove through the bag. The gist is to bear the burden on the ground side and, after hardening the concrete, shrink the bag and remove it from the excavation trench.

Second, the bag is inflated by transferring a stabilizing liquid or mud injected into the digging trench into the bag. Third, the bag is contracted and removed by removing the liquid inside. The gist of the present invention is to discharge the paper, lift it up with a hanging member such as a wire through metal fittings attached to the bag, and carry out the processing.

According to the first aspect of the present invention, in a method of jointing an underground continuous wall in which a joining steel plate is disposed on a joint surface between a preceding element and a following element, the joining is performed when the preceding element is poured into concrete. By inflating the bag provided outside the steel plate, the lateral pressure during concrete casting can be borne on the ground side of the excavation trench through the bag, so that the bonded steel plate can be reinforced and deformation can be prevented. In addition, by inflating the bag body before the concrete is poured, the concrete can be poured at a stretch afterward, and it is not necessary to control the concrete placement height to match the amount of crushed stone as in the related art.

After the concrete is hardened, if the bag is shrunk, it can be easily removed from the inside of the excavation groove, and the bag can be reused, thereby improving the economic efficiency.

According to the second aspect of the present invention, in addition to the above-described operation, the expansion of the bag body is performed by transferring the stable liquid or muddy water to be injected into the excavation groove into the bag body. For example, a liquid can be easily injected into the bag body and inflated simply by installing a pump. In this case, by maintaining the water level in the bag body equal to the water level in the excavation groove, it is possible to prevent the groove wall from being stably maintained.

According to the third aspect of the present invention, in addition to the above functions, the shrinking and removing of the bag body discharges the liquid inside,
Since it can be lifted by a suspending member such as a wire through a hardware attached to the bag body, it is easy. Then, if the liquid in the bag is returned to the excavation groove after collection, the water level in the groove can be kept constant, and the groove wall can be stabilized.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view showing an embodiment of a method of installing a joint of an underground continuous wall according to the present invention, FIG. 2 is a front view of the same, FIG. 3 is a plan view of a main part, and FIG. The same components as those described above are denoted by the same reference numerals.

In the method of the present invention, if the groove of the preceding element 1 for one element is excavated as shown in the work flow of FIG. 6, after the disposal of the mud and the removal of the slime, the rebar cage 3 assembled separately is excavated. 2, and then, to both sides of the reinforcing steel cage 3, a joint steel plate 4 serving as a joint is attached. Further, a bag body 9 that can be expanded and contracted into the excavation groove 2 is provided in a gap 10 between the outside and the ground 8. It is built (see FIG. 8A).

The bag body 9 is made of, for example, a rubber tube, and has a width in the vertical and horizontal directions substantially equal to the size of the side of the reinforcing cage 3, a thickness smaller than the gap 10 in a contracted state, and a width filling the gap 10 in an expanded state. And water supply holes 11 and drain holes 12 are provided at appropriate locations on the upper surface.
A metal member 13 to be lifted by a suspending member such as is embedded.

In the figure, reference numeral 15 denotes a rubber sheet made of a hard rubber plate for preventing the concrete from flowing out to the joint portion when the preceding element 1 is poured into the concrete. It is attached with fasteners such as screws 17.

Further, as shown in FIG. 5, a stabilizing solution 19 to be poured into the excavation groove 2 and a pump 18 for transferring muddy water into the bag body 9 for stabilizing the groove wall are provided at appropriate locations such as the upper portion of the excavation groove 2. Installed in As the stabilizing solution 19, for example, a bentonite type or a polymer type is used.

When the reinforcing cage 3 and the bag 9 are erected in the excavation groove 2 as described above and the concrete outflow prevention work is completed, a stabilizing solution 19 or muddy water is injected into the excavation groove 2 and the water is poured. It is transferred from the water supply hole 11 into the bag body 9 by the pump 18,
The water level in the bag 9 is kept the same as the water level in the digging groove 2 so that the stability of the groove wall is not impaired.

Thus, as shown by a chain line in FIGS.
Further, as shown in FIGS. 5B and 8B, the bag body 9 is inflated into the gap 10, and the ground 8 which is the side wall of the excavation groove 2 and the bonded steel plate 4 are formed.
Then, concrete 5 is poured into the reinforced car 3 in this state.

The lateral pressure applied to the bonded steel plate 4 by the concrete casting is transmitted to the ground 8 via the bag 9 and is supported there. Therefore, the joint steel plate 4
Is not deformed.

After the concrete 5 has hardened, the liquid in the bag 9 is discharged from the drain hole 12 into the excavation groove 2 by the pump 18 to shrink the bag 9 (see FIG. 8 (c)). 14
And lift it off the excavation groove 2. In this case, the liquid in the bag body 9 is returned to the digging groove 2 as described above, so that the water level in the digging groove 2 can be kept constant.

The collected bag 9 can be reused at the next construction site.

In the above-described first embodiment, the bag 9 is built in a separate step after the reinforcing cage 3 is built. However, the present invention is not limited to this. The bag body 9 may be temporarily fixed to the outside of the joint steel plate 4 on both sides of the steel sheet 3 with an adhesive or the like in advance, and the bag body 9 may be simultaneously built by embedding the reinforcing basket 3. In this case, similarly to the first embodiment, after the concrete 5 has hardened, the bag 9 is removed and used for the construction of the next element.

[0029]

As described above, the method for constructing an underground continuous wall according to the present invention is a joint method for an underground continuous wall in which a joining steel plate is disposed on a joint surface between a preceding element and a following element.
By inflating the bag provided on the outside of the joint steel plate at the time of placing the concrete of the preceding element, the lateral pressure at the time of placing the concrete can be borne on the ground side of the excavation groove through the bag, so that the joint steel plate can be reinforced. Deformation can be prevented. In addition, by inflating the bag before casting concrete, the concrete can be poured at once, and there is no need to control the concrete placement height to match the amount of crushed stone as in the past. Improve sexuality.

After the concrete is hardened, if the bag is shrunk, the bag can be easily removed from the inside of the excavation groove, and the bag can be reused, thereby improving the economic efficiency.

The inflation of the bag is performed by transferring a stable liquid or muddy water to be injected into the excavation groove into the bag, so that the liquid can be easily stored in the bag simply by installing a pump for transferring the liquid. Can be injected to inflate. In this case, by maintaining the water level in the bag body equal to the water level in the excavation groove, it is possible to prevent the groove wall from being stably maintained.

Further, shrinkage and removal of the bag can be easily performed by discharging the internal liquid and lifting the bag with a hanging member such as a wire through metal fittings attached to the bag. Then, if the liquid in the bag is returned to the excavation groove after collection, the water level in the groove can be kept constant, and the groove wall can be stabilized.

[Brief description of the drawings]

FIG. 1 is a plan view of a method of constructing a joint of an underground continuous wall according to the present invention.

FIG. 2 is a front view of a method for constructing a joint of an underground continuous wall according to the present invention.

FIG. 3 is a plan view of a main part of a method of constructing a joint of an underground continuous wall according to the present invention.

FIG. 4 is a plan view of a main part of the plan view of FIG. 3 of the method of installing a joint of an underground continuous wall according to the present invention.

FIG. 5 is an explanatory view showing a state in which liquid is injected into a bag body by the method of installing a joint of an underground continuous wall according to the present invention.

FIG. 6 is a flow chart of a work showing a first embodiment of erection of a bag body by a method of constructing a joint of an underground continuous wall according to the present invention.

FIG. 7 is a flow chart of an operation showing a second embodiment of laying a bag in the method of constructing a joint of an underground continuous wall according to the present invention.

FIG. 8 is an explanatory view showing a process of inflation and shrinkage of a bag body in the method of constructing a joint of an underground continuous wall according to the present invention.

FIG. 9 is a plan view of a preceding element showing an example of a conventional method of constructing an underground continuous wall joint.

FIG. 10 is a plan view of a joint steel plate joint which is an example of a conventional method of constructing a joint for an underground continuous wall.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Leading element 2 ... Excavation groove 3 ... Rebar cage 4 ... Joint steel plate 5 ... Concrete 6 ... Trailing element 7 ... Crushed stone 8 ... Ground mountain 9 ... Bag 10 ... Gap 11 ... Water supply hole 12 ... Drain hole 13 ... Hardware 14 ... wire rope 15 ... rubber sheet 16 ... flat steel 17 ... screw 18 ... pump 19 ... stabilizer

Claims (3)

[Claims] 1. Drilling a groove at an interval in the ground, casting concrete to construct a leading element, excavating the ground between the preceding elements, placing concrete in the ground, and setting a subsequent element. In the method of constructing a joint of an underground continuous wall in which the preceding element and the succeeding element are connected to each other at the joint surface at each end, a bag body which can be expanded and contracted outside the joint steel plate disposed on the joint surface At the time of placing concrete in the preceding element, the bag body is inflated at the time of concrete placement, and the side pressure at the time of concrete placement is borne by the ground side of the excavation groove through the bag body. Construction method of joint of underground diaphragm wall characterized by removing from inside. 2. The method according to claim 1, wherein the expansion of the bag body is performed by transferring a stabilizing liquid or muddy water injected into the excavation trench into the bag body. 3. The ground according to claim 1 or 2, wherein the bag is contracted or removed by discharging the liquid therein and lifting the bag with a suspending member such as a wire rope through metal fittings attached to the bag. Construction method of the joint of the middle continuous wall.