JPH0477087B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method of constructing an underground continuous wall.

[Conventional technology]

In the past, underground continuous walls were often used as temporary soil retaining walls and water-stop walls, but as a recent trend, they are often used in main structures, and along with this, super-deep walls and super-walls are being used. It is becoming thicker and rapidly increasing in size.

For underground continuous walls used in such main structures, it is effective to have a structure in which the cross-sectional shape (wall thickness) changes in the depth direction due to design requirements and coordination with other structures during construction. There are many cases.

Conventionally, as shown in Fig. 19, an underground continuous wall 20 with the same cross-section at the top and bottom is constructed, and after the concrete has hardened, the unnecessary part 21 is removed as the internal excavation is carried out to create an underground wall with a reduced cross-sectional diameter at the top. A continuous wall 20' was obtained.

[Problem to be solved by the invention]

When constructing an underground continuous wall with a variable cross-section using the conventional method, concrete must also be poured in unnecessary parts 21, and a lot of work is required to scoop out a large amount of hardened concrete in unnecessary parts 21. It is very troublesome as it takes time and effort to dispose of the scooped-up concrete lumps as industrial waste.

The purpose of the present invention is to eliminate the disadvantages of the conventional example,
An object of the present invention is to provide a construction method for an underground continuous wall that can easily and inexpensively construct an underground continuous wall with a variable cross section.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention has the following objectives: After the completion of excavation and slime treatment, in an excavated trench with the same cross-sectional diameter,
A reinforcing bar cage with a reduced cross-sectional diameter is inserted by dividing the upper part vertically with a partition plate to prevent concrete spillage, and a tremie pipe is built into the reinforcing bar cage, so that the entire cross section of the lower part of the reinforcing bar cage is not reduced as usual. The gist of the project is to pour concrete to the top of the partition, and in the reduced section at the top, filler is placed on the outside of the partition plate for holding down, and the concrete is poured all the way to the top.

[Effect]

According to the present invention, concrete can be poured in accordance with the reinforcing bar cage whose cross-sectional diameter at the top is reduced;
Unlike the conventional method, there is no need to pour concrete into unnecessary areas, so there is no need to scoop up a large amount of concrete from unnecessary areas or to dispose of the concrete that has been scooped out.

〔Example〕

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

Figures 1 to 8 are front views of each process showing one embodiment of the underground wall construction method of the present invention, Figures 9 and 1.
Figure 0 is a side view of the process in Figures 7 and 8.
In the figure, 1 is a leading element, 2 is crushed stone, and 3 is a cover plate that protects the joint muscle at the end of the leading element.

As shown in FIG. 1, an excavation machine 5 (electro mill) suspended from a base machine 4 such as a crawler crane excavates an excavation groove 6 having the same cross-sectional diameter for a trailing element. The inside of the hole is filled with a bentonite solution 7 for preventing collapse of the hole wall.

Then, as shown in FIG.
The cleaning machine 8 is lowered into the cover plate 3 so as to clean the partition steel plate, and the joint portion is cleaned.

As shown in FIG. 3, the cover plate 3 is removed, and as shown in FIG. 4, the slime is treated with an excavator 5 or the like and the bentonite solution 7 is replaced with a good solution.

The above is the same as the conventional example, but as shown in FIG. 5, the present invention suspends a unique reinforcing bar cage 9 into the excavated groove 6 thus obtained.

FIG. 11 and FIG. 12 show an example of this reinforcing bar basket 9, and the lower part 9a is a non-reduced cross-sectional part,
The upper part 9b is vertically partitioned by a concrete outflow prevention partition plate 10 to reduce the cross-sectional diameter.

This concrete spill prevention partition plate 10 is a steel plate,
Although a wooden board may be used, in this example, the wooden board shown in Figs.
As shown in the figure, a frame is formed from angle material 16, a wire mesh 10a made of expanded metal is attached to this frame, and a civil engineering sheet 10b is stretched over one side of the frame in a canvas shape, and the surrounding area is fixed with dry bits 17 to form the frame. In the figure, 18 is a hard rubber plate provided at the end of the frame.

Note that the partition plate 10 may also horizontally partition the upper end of the lower part 9a, which changes from the lower part 9a, which is a non-reduced cross-section part, to the upper part 9b, which is a reduced cross-section part.

In this way, the upper part 9b of the reinforcing bar cage 9 is partitioned in the vertical direction by the partition plate 10 so that the cross-sectional diameter is reduced, but there are also reinforcing bars 1 in a lattice shape on the outside of the partition plate 10.
1 is assembled, and the width of the outer shape is made the same on the top and bottom to ensure ease of setting into the excavated groove 6. In the figure, reference numeral 12 denotes a spacer for ensuring clearance with the hole wall of the excavated groove 6.

As shown in FIG. 6, a tremie pipe 13 is built into the reinforcing bar cage 9, and as shown in FIG. 7 and FIG. 14.

FIG. 13 to FIG. 16 are longitudinal sectional side views of each step showing the state of placing concrete 14 as described above.

Above the cross-sectional change point L, as shown in FIGS. 8 and 10, concrete 14 is placed in advance, and crushed stone 15 is placed as a holding filler on the outside of the partition plate 10 with a delay of within 500 mm. Insert it. In this way, in parallel with the pouring of concrete 14, crushed stone 1 is used to maintain a balance with the concrete pressure.
5 and pour concrete 14 up to the top of the underground continuous wall.

Furthermore, crushed stone 15 is added to the entire section of the underground continuous wall from the top A to GL to complete the construction.

Moreover, the crushed stone 15 is removed at the time of internal excavation after completion of the underground continuous wall to complete the underground continuous wall with a variable cross section.

Although the above embodiments have been described with respect to one cross-sectional change point L, the present invention is also applicable to cases with multiple cross-sectional changes, and
As the filling material for holding down the outside of the partition plate 10,
Regardless of crushed stone, earth and sand, rubber packer (filled with water),
The use of boxes, steel supports, etc. may also be considered.

〔Effect of the invention〕

As described above, the method for constructing an underground continuous wall of the present invention is to construct an underground continuous wall with a variable cross section in which the cross-sectional diameter of the upper part is reduced, without pouring concrete into unnecessary parts as in the conventional method. This is not the case, and it can be constructed easily and inexpensively, and the construction period can be shortened.

[Brief explanation of drawings]

Figures 1 to 8 are front views of each process showing one embodiment of the underground wall construction method of the present invention, Figures 9 and 1.
Figure 0 is a side view of the steps in Figures 7 and 8, Figure 11 is a side view of the reinforcing bar basket used in the present invention, and Figure 1
Figure 2 is a side view of the main part of the same as above, Figures 13 to 16 are side views showing the state of concrete placement, Figure 17 is a cross-sectional plan view of the partition plate part, Figure 18 is a front view of the same as above, Figure 19 The figure is an explanatory diagram showing a conventional example. 1... Leading element, 2... Crushed stone, 3... Cover plate, 4... Base machine, 5... Excavator, 6... Excavation groove, 7... Bentonite solution, 8
... Cleaning machine, 9 ... Reinforced cage, 9a ... Lower part, 9b
... Upper part, 10 ... Partition plate, 10a ... Wire mesh, 1
0b... Civil engineering sheet, 11... Reinforcement bar, 12...
spacer, 13... tremie pipe, 14... concrete, 15... crushed stone, 16... angle material,
17...Drybit, 18...Rubber plate, 20,
20'...Underground continuous wall, 21...Unnecessary part.

Claims (1)

[Scope of Claims] 1. After the excavation and slime treatment are completed, a reinforcing bar cage whose cross-sectional diameter is reduced by vertically partitioning the upper part with a concrete outflow prevention partition plate is inserted into the excavated trench with the same cross-sectional diameter. Then, a tremie pipe is built inside the reinforcing bar cage, and concrete is poured over the entire cross section of the non-reduced cross section at the bottom of the reinforcing bar cage as usual, and filler is placed on the outside of the partition plate in the upper reduced cross section. An underground continuous wall construction method characterized by pouring concrete all the way to the top with objects in between. 2. Construction of an underground continuous wall according to claim 1, wherein the filling material for holding down is crushed stone, and this crushed stone is poured in while concrete is being poured in advance in the reduced cross-sectional area of the upper part of the reinforcing bar cage. Law. 3. The construction method for an underground continuous wall according to claim 1, wherein the concrete outflow prevention partition plate is composed of a wire mesh and a civil engineering sheet.