JPS6320968B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a suitable method for constructing a continuous underground wall, in which the continuous wall is installed underground to construct a water stop, a mountain stop, an underground structure, etc. using cast-in-place concrete.

Generally, when constructing subway side walls or underground walls of buildings on soft alluvium, sheet pied, H
In order to prevent construction pollution such as noise and vibration caused by the driving of shaped steel and piles, continuous underground walls are constructed using mechanical excavation and cast-in-place concrete.

Figures 1A to 1E are explanatory diagrams showing a conventional method of constructing a continuous underground wall.A continuous underground wall consists of repeating elements as a single wall determined by geological conditions and wall specifications. It is formed by constructing and connecting those elements. That is, first, as shown in FIG. 1A, a plate-shaped trench 3 is excavated by a bucket excavator 2 in a portion adjacent to the existing element 1 on the continuous wall construction line. Here, the inside of the trench 3 is filled with bentonite muddy water 4 to protect the inner wall of the trench 3 from collapse. Next, as shown in FIG. 1B, an interlocking pipe 5 as a joint between the elements is inserted into the side wall of the trench 3 facing the existing element 1, and further, as shown in FIG. Then, a reinforcing bar cage 6 is inserted into the trench 3 filled with bentonite slurry 4. Next, as shown in FIG. 1D, concrete 8 is poured from the bottom of the trench 3 using a tremie pipe 7, replacing the bentonite slurry 4. Finally, as shown in FIG. 1E, the solidification state of the concrete 8 is checked, the interlocking pipe 5 is pulled out, and a new element 9 that is continuous with the existing element 1 is obtained. By repeating these steps, a wall with continuous elements can be obtained.

However, in the method of constructing a continuous underground wall according to the above-mentioned conventional example, the inner wall of the trench 3 collapses and falls due to a decrease in the water level of the bentonite mud 4 inside the trench 3, a decrease in the quality of the bentonite mud 4, etc. Due to the danger of
The trench 3 is deep and it is difficult to obtain a continuous wall with a large height. In addition, since the concrete 8 forming the continuous wall is cast in the bentonite muddy water 4, the concrete 8 becomes uneven and has insufficient adhesion to the reinforcing bars, making it difficult to maintain the concrete strength of the continuous wall. There are problems such as difficulty in maintaining the condition.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a method for constructing a continuous underground wall that can safely obtain a continuous wall of high quality.

In order to achieve the above object, the continuous underground wall construction method according to the present invention involves excavating a plate-shaped trench,
Concrete mortar is sprayed on the inner surface of the trench while a net is stretched, a reinforcing cage is inserted inside the trench, and concrete is poured inside the trench.

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

FIGS. 2 and 3 are explanatory diagrams showing one embodiment of the continuous underground wall construction method according to the present invention. On the high line of the continuous wall and adjacent to the existing element 11, an upper trench 1 with a height L1 of a plate-shaped trench 12 is formed using a bucket excavator or the like.
2A is excavated. Support rails 13 are disposed on two sides of the opening of the upper trench 12A along the continuous wall extension direction, and a support rail 14 is disposed on one side of the opening facing the existing element 11. A net 15 made of a wire mesh having a thickness depending on the geology and depth of the trench is suspended from the support rail 13 via a hook 16, and a net 17 is similarly suspended from the support rail 14 via a hook 18. suspended through. These nets 15, 17 are attached to the inner surface of the upper trench 12A by anchors 19 driven into the trench. In addition, Net15,
Concrete mortar is sprayed on the top side of 17, and the concrete mortar is
7 to the inner surface of the upper trench 12A.

After the inner surface of the upper trench 12 is protected from collapse by the concrete mortar in this way, an intermediate trench 12B having a height L2 of the trench 12 is excavated, and the upper trench 12 is
A net 20 is suspended from the lower end of the net 15 attached to A via a hook 21.
A net 22 has a hook 23 at the bottom end of the net 17.
suspended through. Net 20 and 22 are
The anchor 19 is attached to the inner surface of the intermediate trench 12B. In addition, Net2
Concrete mortar is sprayed on the top surface of 0,22, and the concrete mortar is NET20,
22 to the inner surface of the intermediate trench 12B.

After the inner surface of the intermediate trench 12B is protected from collapse in this way, a lower trench 12C having a height L3 of the trench 12 is excavated, and the net 2 disposed in the intermediate trench 12B is excavated.
A net 24 is suspended from the lower end of 0 via a hook 25. A net 26 is suspended from the lower end of the net 22 via a hook 27. Further, the nets 24 and 26 are attached by anchors 19 to the inner surface of the lower trench 12C. Further, concrete mortar is sprayed onto the upper surfaces of the nets 24 and 26, and the concrete mortar is applied to the lower trench 1 through the nets 24 and 26.
It is fixed on the inner ground of 2C.

As described above, concrete mortar is applied to the front surface of the inner ground, and a reinforcing cage is inserted into the trench 12 while the concrete mortar is protected from collapse. Concrete is placed and an extension element that is continuous to the existing element 11 is constructed.

In addition, when the above-mentioned continuous wall is constructed on the alluvial ground plate, as shown in FIG.
for each block, i.e., the upper trench 12
A, middle trench 12B and lower trench 1
A safer construction environment is created by penetrating the riser pipe 31 at each level corresponding to 2C and lowering the groundwater level around the continuous wall construction part by a height H from level 31A to level 31B.

According to the above embodiment, each time the excavation of the trench 12 progresses to a predetermined depth, a net is pasted and concrete mortar is sprayed onto the inner surface of the ground, thereby preventing the inner surface of the ground from collapsing. Falling is protected, and it becomes possible to construct deep walls without filling the trench with muddy water. Moreover, since the concrete forming the continuous wall is cast inside the trench 12 without muddy water, it is homogeneous and has a large adhesion force to the reinforcing bars, making it possible to obtain a concrete wall with high strength. Furthermore, since a net is also provided on the inner surface of the trench 12 in the direction in which the continuous wall is extended, facing the existing element 11, the net in this area not only prevents the collapse of the ground but also serves as a joint between the elements. It can function well as well.

As described above, the method for constructing a continuous underground wall according to the present invention involves excavating a plate-shaped trench, spraying concrete mortar on the inner surface of the trench with nets stretched, and reinforcing steel inside the trench. Since the cage is inserted and concrete is poured inside the trench, it is possible to safely obtain a high-quality continuous underground wall.

[Brief explanation of the drawing]

Figures 1A, B, C, D, and E are cross-sectional views showing the construction order of a conventional continuous underground wall construction method;
The figure is a sectional view showing an embodiment of the method for constructing a continuous underground wall according to the present invention, and FIG. 3 is a sectional view taken along the - line in FIG. 2. 12, 12A, 12B, 12C...trench,
15, 17, 20, 22, 24, 26...Net, 19...Anchor.

Claims (1)

[Claims] 1. A plate-shaped trench is excavated, concrete mortar is sprayed on the inner surface of the trench with a net stretched over it, a reinforcing cage is inserted inside the trench, and concrete is poured inside the trench. A method of constructing a continuous underground wall.