JPH09235726A - Construction method of underground continuous wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the placement speed of concrete when constructing an underground continuous wall. SOLUTION: A method, which constructs an underground wall A as an element, is designed to secure a connection space 7 with an adjacent wall outside a partition plate 6 by excavating a groove 2 for an underground wall underground, positioning a cage 4 into the groove 4, placing concrete 10 into an inside space segmented with the partition plate 6 mounted on the cage 4 by way of a tremie pipe. Prior to concrete placement, a porous pipe 20 is inserted into the cage 4 so as to suck up the moisture contained in the concrete. While the concrete 10 is being placed, the moisture contained in the concrete 10 is sucked up with the porous pipe 20 and drained, thereby lowering the fluidity of the placed concrete 10 and reducing a lateral pressure acting on the partition plate 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing an underground continuous wall by placing concrete on site to construct an underground wall.

[0002]

2. Description of the Related Art An example of a conventional underground continuous wall construction method will be described with reference to FIGS. 5, 6, and 7. In this construction method,
As shown in FIG. 7, first, the underground continuous wall H to be constructed is divided into a leading element A and a trailing element B. Then, as shown in FIG. 7 (a), the preceding element A is installed in advance at an interval, and then, as shown in FIG. 7 (b).
As shown in FIG. 5, the trailing element B is applied to the portion sandwiched by the leading elements A and A on both sides, thereby completing the continuous underground wall (underground continuous wall) H.

In constructing the preceding element A, first, referring to FIG.
As shown in (a), a groove 2 having a predetermined depth and a predetermined length for making an underground wall is excavated in the ground 1 (in the soil), and the slime 3 is removed. Next, as shown in FIG. 5 (b), the reinforcing bar cage 4 is hung inside the groove 2 by a crane to be built. At that time, the partition plate 6 and the vera sheet 8 are attached to the reinforcing bar 5 of the reinforcing bar car 4. The vera sheet 8 is provided in a portion facing the soil wall in the width direction of the groove 2 (thickness direction of the underground continuous wall). This part is strong enough to withstand the required concrete pressure. Further, the partition plate 6 is attached to the reinforcing bars 5 located at both ends in the length direction of the groove 2 by using a connecting member (not shown). In this case, it is provided outside the partition plate 6 (both ends in the length direction of the groove 2) so as to secure a space 7 for connection with the succeeding element.

After the reinforcing bar cage 4 is built in, as shown in FIG. 5 (c), the tremie pipe 9 is inserted into the inner space surrounded by the partition plates 6 and 6 and the vera sheets 8 and 8. Concrete 10 is poured. Then, the underground wall as the preceding element A is completed.

As shown in FIG. 7A, the preceding element A
When the above is completed, next, as shown in FIG. 6D, the earth and sand 11 between the preceding elements A and A is removed, and the groove 12 of the remaining portion between the preceding elements A and A is excavated. This groove 12
Is connected to the connecting spaces 7, 7 on both sides left when the preceding element A is constructed. Next, as shown in FIG. 6 (e), a reinforcing bar cage 14 is built in this groove 12, and after the reinforcing bar cage 14 is built in, concrete 10 is put through the tremie pipe 9 as shown in FIG. 6 (f). A trailing element B, which is cast and connected to the reinforcing bars 5 of the preceding element A, is constructed, thereby completing the underground continuous wall H.

[0006]

[Problems to be Solved by the Invention] In the above construction method,
When constructing the preceding element A, the trailing element B to be constructed next by the partition plate 6 attached to the rebar cage 4
A space 7 for connection with is secured. Therefore, when the concrete 10 is cast, the lateral pressure of the concrete 10 must be entirely received by the partition plate 6 and the vera sheet 8. In this case, since the concrete 10 contains water necessary for obtaining the required workability and is placed in a state of high fluidity, as the placement height increases, a large lateral pressure due to the fluid is applied to the partition plate. It will be at the bottom of 6. For this reason, concrete 10 is slowly poured while waiting for the progress of setting to some extent so that the lateral pressure does not become excessive.

However, for example, when constructing an underground continuous wall having a depth of 100 m or more, if concrete is poured at a speed of 5 m / h, it takes 20 hours or more for construction. Therefore, due to the construction time, soaring costs,
In the case of residential areas, nighttime noise problems will arise.

In view of the above circumstances, the present invention provides a method for constructing an underground continuous wall, which is capable of increasing the concrete pouring speed and shortening the construction time by taking simple measures. To aim.

[0009]

According to a first aspect of the present invention, a groove for constructing an underground wall is excavated in the soil, a rebar cage is built in the groove, and a partition plate attached to the rebar cage is defined. In the method of constructing an underground continuous wall where concrete is placed in the inner space via a tremie pipe and the space for connecting with the adjacent wall is secured outside the partition plate, before the concrete is placed in the construction method of the underground continuous wall. By inserting a wicking member to wick moisture in the concrete into the reinforced basket and pouring the concrete, the wicking member wicks the moisture in the concrete and drains it to improve the fluidity of the placed concrete. It is characterized by lowering the lateral pressure acting on the partition plate.

In this case, as the suction member, a perforated pipe having a large number of holes in the pipe wall as in the invention of claim 2 or a long non-woven fabric as in the invention of claim 4 is used. can do. When a perforated pipe is used, it is preferable that a filter material for preventing concrete from flowing into the pipe is provided on the outer periphery of the perforated pipe as in the invention of claim 3.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. The construction method of this embodiment is the construction method of the continuous underground wall shown in FIG. 5 to FIG. 7, with some improvements made in constructing the preceding element A. That is, before placing the concrete 10, as shown in FIGS. 1 and 2, the concrete 1
A perforated pipe 20 (sucking member) for sucking up the water in 0 is inserted, and while pouring the concrete 10, the water 22 in the concrete 10 is sucked up by the perforated pipe 20 and drained. Other configurations are the same as those of the above-mentioned conventional example.

As shown in FIG. 3, the perforated pipe 20 has a large number of holes 20a in the pipe wall and is arranged so as to be positioned inside the concrete 10 at appropriate intervals, and its outer periphery is a filter. It is covered with a non-woven fabric 21 as a material so that the concrete 10 does not flow into the pipe.

By inserting such a perforated pipe 20 into the rebar cage 4 and then placing concrete 10,
By actively removing the water 22 in the concrete 10,
The fluidity of the cast concrete 10 can be reduced. That is, the weight of the cast concrete 10 is dewatered under pressure to positively lose the fluidity of the concrete 10 and promote apparent coagulation, thereby reducing the lateral pressure on the partition plate 6. Can be achieved. Therefore, due to the effect of reducing the lateral pressure, the pouring speed of the concrete 10 can be increased. For example, by changing the pouring speed from 5 m / h to 7 m / h, 1
It takes 2 hours to construct a continuous underground wall of 00m.
It can be shortened from 0 hours to about 15 hours. As a result, I was able to finish the work in the middle of the night,
Rationalization of construction and cost reduction can be achieved.

In addition to the perforated pipe 20, as shown in FIG. 4, a long non-woven fabric 30 may be arranged along the vera sheet 8 as a suction member, or the vera sheet 8 itself may be drained. It may have a function.

[0015]

As described above, according to the first aspect of the present invention, the moisture is removed from the concrete that has been cast by the suction member, and the concrete is cast while the pressure dehydration is promoted by the weight of the concrete. The fluidity of concrete can be reduced, and the lateral pressure acting on the partition plate can be reduced. Therefore, due to the side pressure reduction effect, the concrete pouring speed can be increased,
It is possible to rationalize construction and reduce costs. As the suction member, a perforated pipe as in the invention of claim 2 or a long non-woven fabric as in the invention of claim 4 can be used. It is technically easy to realize by simply adding a new member. When a perforated pipe is used, by covering the outer periphery with a filter material as in the third aspect of the invention, it is possible to prevent the concrete from flowing into the pipe, and it is possible to remove only water.

[Brief description of drawings]

FIG. 1 is a plan view showing a state in which concrete for a subterranean wall as a preceding element is placed by a construction method according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II of FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is a plan view showing a state in which concrete of a subterranean wall as a preceding element is placed by a construction method according to another embodiment of the present invention.

FIG. 5 is an explanatory diagram of a conventional underground continuous wall construction method,
(A), (b), (c) is a figure which shows the process at the time of constructing a preceding element in order, (a), (b), (c)
The upper figure is a vertical sectional view along the wall surface of the underground wall, and the lower figure is a horizontal sectional view of the underground wall.

FIG. 6 is an explanatory view of a conventional underground continuous wall construction method,
Drawings (d), (e), and (f) are views showing the steps in the case of constructing the trailing element in order, and (d), (e), and (f)
The upper figure is a vertical sectional view along the wall surface of the underground wall, and the lower figure is a horizontal sectional view of the underground wall.

[Fig. 7] Fig. 7 is a schematic diagram used for explaining the order of construction of a conventional underground continuous wall, in which (a) shows a state in which a preceding element is constructed and (b) shows a state in which a trailing element is constructed next. is there.

[Explanation of symbols]

 2 groove 4 rebar cage 6 partition plate 7 connecting space 9 tremie pipe 10 concrete 20 perforated pipe (sucking member) 20a hole 21 non-woven fabric (filter material) 30 non-woven fabric (sucking member)

Claims (4)

[Claims] 1. A trench for constructing an underground wall is excavated in the soil, a rebar cage is built in the trench, and concrete is inserted through a tremie pipe into an inner space defined by a partition plate attached to the rebar cage. In the method of constructing an underground continuous wall that is placed and constructs an underground wall in a state where a space for connection with an adjacent wall is secured on the outside of the partition plate, before the concrete placing, the water content in the concrete in the rebar cage Insert a suction member to suck up
While pouring concrete, the suction member absorbs the water in the concrete and drains it.
A method for constructing an underground continuous wall characterized by reducing the fluidity of cast concrete. 2. The method for constructing an underground continuous wall according to claim 1, wherein a perforated pipe having a large number of holes in the pipe wall is used as the suction member. 3. The method for constructing a continuous underground wall according to claim 2, wherein the perimeter of the perforated pipe is covered with a filter material for preventing concrete from flowing into the pipe. 4. The method for constructing an underground continuous wall according to claim 1, wherein a long non-woven fabric is used as the suction member.