JPH0517327B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to an underground continuous wall construction method, and particularly to improving the ease of extracting partition plates from joint boxes.

<<Prior Art>> As one of the construction methods for forming a continuous underground wall while excavating underground, there is a conventional underground continuous wall construction method shown in FIGS. 3 and 4.

In the figure, reference numeral 1a indicates a preliminary drilling hole, and a hollow joint box 2 is installed at one end of this drilling hole 1.
By inserting a reinforcing bar cage 3 provided with a steel bar and pouring concrete into the excavated hole 1a, a leading wall body 7 is formed in a portion excluding the joint box 2.

The joint box 2 is composed of a pair of side plates 4, a joint plate 5, a bottom plate (not shown), and a partition plate 6 located at the side end of the joint box 2 and supported by an angle 4a. The partition plate 6 can be pulled out in the vertical direction, and after the formation work of the preceding wall is completed, a new trailing excavation hole 1b is continuously excavated to the side end side of the partition plate 6, and then pulled out, and the completed excavation is completed. A reinforcing bar cage 3' having a joint box integrated at its tip end is inserted into the hole 1b in the same manner as described above. and,
The ends of the reinforcing bar cages 3 and 3' are placed in an overlapping state within the joint box 2, and new concrete is poured in this state to create a continuous trailing wall 8 that is connected to the leading wall 7. It is formed by

<<Problems to be solved by the invention>> The problem with this construction method is that when the depth of the excavation hole 1 is deep, the length of the partition plate 6 becomes extremely long, making it difficult to pull out or insert it. .
For example, the maximum depth of the excavation hole 1 is currently about 45 m, and there is a possibility that it will become 60 to 80 m in the future. Operation becomes difficult.

On the other hand, if the distance between the angle 4a and the partition plate 6 is increased in order to facilitate insertion or withdrawal, the sealing performance of the partition plate 6 will not be sufficient. Soil may enter through the gap between the partition plate 6 and the angle 4a, or concrete filled between the preceding excavation hole 1a and the side plate 2 may enter the partition plate 6 and the angle 4.
There was also a risk that it would get into the gap between a and the partition plate 6 and fix the partition plate 6.

The present invention was made in view of the above-mentioned problems, and an object of the present invention is to provide an underground continuous wall construction method that allows easy insertion and removal of partition plates.

<<Structure of the Invention>> In order to achieve the above-mentioned object, the present invention provides a structure in which the ends of the built-in reinforcing bar cage are overlapped with each other in a hole for excavating a reinforcing bar cage provided with a hollow joint box at one end. In the underground continuous wall construction method in which the trailing wall is sequentially connected, the joint plate of the joint box is buried, and the partition plate and side plate are each removable, and between the partition plate and the excavation hole. After filling with a filler such as crushed stone, the side plate is pulled out while the poured concrete is in a semi-hardened state, and the partition plate is pulled out after the trailing excavation hole is formed on the side of the filler. .

<<Function>> The filler prevents the poured concrete from going around to the partition plate side of the joint box and ensures ease of pulling out the partition plate.

Furthermore, since the side plates are pulled out from the cast concrete in a semi-hardened state, this process is relatively easy.

<<Example>> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a plan view showing one embodiment of the underground continuous wall construction method according to the present invention in the order of steps.

The construction method shown in the figure is similar to the conventional construction method described above, in which a preliminary excavation hole 1a is excavated, a reinforcing bar cage 3 with a joint box 10 attached to the connecting end is inserted, and concrete is poured. Leading wall 7
After forming, a trailing excavation hole 1b is formed on the side of the joint box 10, and another reinforcing bar cage 3' is inserted so that the ends of the reinforcing bar cages 3 and 3' overlap, and then concrete is poured. The trailing wall bodies 8 are sequentially connected and formed by pouring, and these structures are the same.

The construction method shown in the figure is characterized by the following points.

That is, after the reinforcing bar cage 3 is erected in the pre-excavation hole 1a, a relatively coarse filler 11 such as crushed stone is filled between the outer end of the joint box 10 and the side end of the pre-excavation hole 1a.

Here, the joint box 10 of the present invention includes:
Joint plate 1 interposed between wall bodies 7 and 8 to be connected
2, a pair of side plates 14, 14 located on the side surfaces of the drilling holes 1a, 1b, and a partition plate 16 that is pulled out after the trailing drilling hole 1b is formed.

The joint plate 12 is attached vertically to a reinforcing bar cage 3 consisting of horizontal reinforcements 3a and vertical reinforcements 3b braided in a lattice shape, with the horizontal reinforcements 3a penetrating through it. The clamping plates 18, 18 are attached to pass through the horizontal reinforcement 3a, and the joint plate 1
2 and the respective clamping plates 18, 18 are maintained at intervals by connecting members 20 disposed at appropriate intervals in the vertical direction.

On the other hand, the partition plate 16 has a U-shaped cross section, with a pair of side parts 16b perpendicular to the flat base part 16a integrally formed with a high-rigidity material at both ends of the flat base part 16a.
b, 16b extend along the inner surfaces of the side plates 14, 14, and are arranged such that their respective ends abut against the clamping plates 18, 18.

The side plate 14 has a pair of protrusions 14 at both ends.
a, 14a are formed, one protrusion 14a is fitted between the joint plate 12 and the clamping plate 18, and the other protrusion 14a is engaged with the outer surface of the partition plate 16 to form a partition. It is attached so that it can be pulled out so as to embrace the side portion 16b of the plate 16.

Once the reinforcing bar cage 3 has been erected, concrete is poured except for inside the joint box 10.

The poured concrete tries to go around to the partition plate 16 side from the gap between the side plate 14 and the excavated hole 1a, but since the above-mentioned filler material 11 is present here, this prevents it from going around. .

After the concrete is placed, the cement hardens and becomes semi-hardened, that is, hard enough to maintain its own self-supporting state, and then the side plates 14, 14 are pulled out.

Since the drawing is carried out while the cast concrete is in a semi-hardened state, it can be carried out relatively easily, and after drawing, a void 22 is formed at the position where the side plates 14, 14 were located, as shown in FIG. 1B.

Next, a trailing excavation hole 1b is drilled on the side of the partition plate 16.

In this case, the filler material 11 is destroyed during excavation,
The partition plate 16 is gradually exposed, and the filler 11 is also removed by forming the trailing excavation hole 1b.

When the formation of the trailing excavation hole 1b is completed, the partition plate 16 is pulled out.
The surrounding area is not restricted by the void 22 and the removal of the filler 11, and it is not buried in the preceding wall 7, so it can be easily pulled out.

After that, another reinforcing bar cage 3' with a joint box 10 attached to the other end is inserted into the trailing excavation hole 1b, and the ends of the reinforcing bar cages 3 and 3' are overlapped (see Fig. 1C). ), concrete is placed and the trailing wall 8 is connected and formed.

Thereafter, by repeating the above steps in order, a predetermined underground continuous wall is formed.

In the above embodiment, each component plate of the joint box 10 is attached to the reinforcing bar baskets 3 and 3' in advance and is constructed in the excavated holes 1a and 1b. However, for example, the excavated holes 1a and 1b are compared. When the target is shallow, the joint plate 12, side plate 14, etc.
It may be installed after construction.

Furthermore, prior to concrete pouring of the trailing wall 8, the hot position of the joint box 10 may be cleaned and treated with slime.

≪Effects of the Invention≫ As explained above in detail in the examples, according to the underground continuous wall construction method of the present invention, the side plates of the joint box can be easily pulled out while the poured concrete is in a semi-hardened state. At the same time, the poured concrete is prevented from going around by the filling material,
In addition, since the side plates are also pulled out from the front, the partition plates can also be easily pulled out, making it possible to shorten the construction period.

[Brief explanation of drawings]

Figures 1A, B, and C are plan views of essential parts showing an example of the method of the present invention in the order of steps, Figure 2 is a side view of a reinforcing bar basket, and Figures 3 and 4 show the steps of the conventional method in order. FIG. 3 is a plan view of each. 10... Joint box, 11... Filler, 12... Joining plate, 14... Side plate, 16... Partition plate, 18... Holding plate.

Claims (1)

[Claims] 1. In the underground continuous wall construction method, a reinforcing bar cage with a hollow joint box provided at one end is built into the excavation hole, and the ends of the reinforcing bar cages are overlapped to sequentially connect the leading and trailing walls. While the joint board of the joint box is buried, the partition board and side board are made removable, and after filling the space between the partition board and the excavation hole with filler such as crushed stone, the poured concrete is semi-hardened. An underground continuous wall construction method characterized in that the side plate is pulled out in a state where the partition plate is pulled out, and the partition plate is pulled out after forming the trailing excavation hole on the side of the filler.