JP2811022B2 - Underground continuous wall method - Google Patents

Description

The present invention relates to an underground continuous wall construction method.

In the present application, the “underground continuous wall method” refers to a method of replacing a stable liquid in a trench drilled while filling with a stable liquid with a solidifying material such as concrete, and a method of muddy water called a mud solidified wall method. In the present application, the term "stabilizing liquid" is used to include both a method of solidifying with a solidifying agent and a method of solidifying with a solidifying agent. ) And the stabilizing liquid are hardly mixed, and include both solidifying materials such as concrete which solidify itself.

[Prior Art] Conventionally, a trench 1 having a predetermined depth while being filled with a stabilizing solution M
Then, a solidification material injection pipe 2 is inserted into the trench 1, and the solidification material S is injected from the lower end opening 2a while the solidification material injection pipe 2 is pulled up. Have been.

[Problems to be Solved and Used by the Invention] However, in the above-mentioned conventional method, as shown in FIG. 3, when a new underground wall W2 is constructed in succession to the existing underground wall W1, the existing underground wall is not used. A mud cake layer M 'is formed at a portion where W1 and the new underground wall W2 are connected, which has a disadvantage that the water stopping property and integrity of the continuous underground wall may be impaired.

That is, in order to construct a new underground wall W2 continuously to the existing underground wall W1, one end of the existing underground wall W1 is partially cut (hereinafter, when drilling a new trench, the existing underground wall W1 is cut).
Is excavated, and the surface formed at the end of the existing underground wall W1 is simply referred to as a new end surface.) A new trench is drilled. Of course, this new trench is also drilled while filling the trench with the stabilizing solution M. The stabilizing solution M is used for the purpose of forming a mud cake layer M 'on the inner wall of the trench to prevent collapse of the inner wall of the trench, and the mud cake layer M' is formed only on the ground surface portion of the inner wall of the trench. However, in practice, the mud cake layer M 'is also formed on the new section. The thickness of the mud cake layer M 'formed on this new cross section increases as the viscosity and specific gravity of the stabilizing liquid M increases, and the thickness of the generally used stabilizing liquid M is about 1 to 2 mm. It was confirmed that when the viscosity and specific gravity of the stabilizer M were increased, the thickness of the mud cake layer M ′ exceeded 1 cm.

[Purpose] Accordingly, the present invention has been made in view of the above-mentioned drawbacks, and has as its object to provide an underground continuous wall construction method in which a mud cake layer M 'is not formed on a new section.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the constitution of the present invention, which has the above-mentioned claims, has been proposed in order to solve the above-mentioned problems.
After filling the trench 1 having a predetermined depth while satisfying the conditions, the solidification material injection pipe 2 is inserted into the trench 1, and the solidification material S is injected from the lower end opening 2a while pulling up the solidification material injection pipe 2. In the underground continuous wall construction method as described above, a stabilizing liquid stirrer 3 is fixed to a lower portion of the solidifying material injection pipe 2, and when the solidifying material S is injected from the lower end opening 2 a of the solidifying material injection pipe 2, the stable liquid stirring is performed. The technical means is characterized in that the stabilizing liquid layer above the lower end opening 2a is stirred by the machine 3.

[Operation] Therefore, according to the method of the present invention, when the stabilizing solution M is stirred by the stabilizing solution stirrer 3, the mud cake layer M 'is formed on the existing basement wall W1.
Peeled off from the surface. Usually, the mud cake layer M 'has a strong adhesion to the ground surface where the permeability of the stabilizing liquid M is good, and a small thickness as well as poor adhesion to the new end face having a low permeability. If the stirring is set to such an extent that the mud cake M 'on the ground surface is not peeled off by the agitating flow, it has an effect of peeling off only the M' cake M 'on the surface of the new end face.

Embodiment Next, an embodiment of the present invention will be described below with reference to the accompanying drawings.

In the figure, W1 is an existing basement wall, and 1 is a trench that has been drilled to a predetermined depth while being filled with a stable liquid M.

In the present embodiment, the drilling of the trench 1 is omitted in the figure, but a plurality of milling bits (three in order to drill the trench 1 of the first embodiment) are juxtaposed on the lower surface. Using a conventionally known multi-axis rotary excavator, the milling bit is pressed and rotated on the ground to drill holes, and the excavated soil is discharged to the ground by circulating the stabilizing liquid M. However, this excavator may use another known type such as a clamshell bucket, and of course, a conventionally known type adapted to the type of the excavator can be used for discharging excavated soil to the ground. Furthermore, the cross-sectional shape of the drilled trench 1 is not limited to the illustrated example, but is determined by the excavator such as a circle or a rectangle. In the case where the trench 1 is to be drilled at a portion connected to the existing underground wall W1, as shown most clearly in FIG. The connection is measured in the same way as before.

After drilling a trench 1 having a predetermined depth, a solidification material injection pipe 2 is inserted into the trench 1, and the solidification material injection pipe 2 is pulled up from the lower end opening 2a while the solidification material injection pipe 2 is pulled up.
Inject.

FIG. 2 shows a state in which the solidification material S is being injected. When the solidification material S is injected, the trench 1 is usually used.
The stable liquid M was pumped from the upper part of the container, and when the concrete was used as the solidified material S, the stabilized liquid M was temporarily stored in a tank or the like, and when the cement was used as the solidified material S, it was pumped. The step of mixing and stirring the cement into the stabilizing solution M and returning it to the bottom of the trench 1 is the same as the conventional one, and if necessary, a reinforcing bar is inserted into the trench 1 and then the solidified material S is injected. It may be. Although three solidification material injection pipes 2 are used in the illustrated example, the solidification material injection pipe 2 has a relationship between the cross-sectional area of the trench 1, the diameter of the solidification material injection pipe 2, and the capacity of the pressure source of the stabilizer S. However, since the solidified material S usually has a high specific gravity and a high viscosity, it is desirable that the number and the insertion position are determined so that the solidified material S is almost flatly supplied to the bottom of the trench 1.

In the present invention, a stabilizing liquid stirrer 3 is fixed to a lower portion of the solidified material injection pipe 2 and a lower end opening 2a
When the more solidified material S is injected, the stable liquid stirrer 3 stirs the stable liquid layer above the lower end opening 2a.

As the above-mentioned stabilizing liquid stirrer 3, an underwater mixer as shown in FIG. 4 can be used. The stable liquid stirrer 3 including the underwater mixer is provided with a propeller 12 on a drive shaft 15 of a motor 11, and a draft ring is provided outside the propeller 12.
13 and this draft ring 13 has fixed arms 14, 14, 14
Are connected and fixed to the motor 11 portion, and when the motor 11 is rotated in the stabilizing liquid M, the stabilizing liquid M is sucked from the rear side of the propeller 12 (upper in FIG. 4) and passes through the inside of the draft ring 13. It is designed to flow in front of the propeller 12 (downward in FIG. 4). In this embodiment, the underwater mixer 10 is connected to the connecting arm 1 such that the tip of the drive shaft 15 faces downward.
It was fixed to the solidification material injection pipe 2 at 6,16. That is, the stirring flow of the stabilizing liquid M is made to flow downward of the trench 1. In comparison with this method, when the stirring flow is a rotational flow about the longitudinal axis of the trench 1, the The cake cake M 'is peeled to a considerable height from the bottom where the solidified material S is injected, and the mud cake M' at the ground portion is also easily peeled off. If the direction of the stirring flow is directed to the bottom, This is because the stirring flow collides with the solidified material S layer having a large specific gravity at the bottom and changes its direction, and the mud cake M ′ formed on the inner wall surface of the trench 1 is sequentially peeled from the lower end thereof. Even if the mud cake M 'in the ground part is peeled off, the mud cake M' is filled with the solidified material S in a short time, so that the possibility of collapse is prevented accordingly.

Another reason that the direction of the stirring flow is directed to the bottom is that it is easy to control a large flow rate at the portion facing the existing basement wall W1, and as shown in FIG. At the time of fixing to the material injection pipe 2, if the stabilizing liquid stirrer 3 is attached to the side near the new end face, the flow rate can be increased at the portion facing the existing underground wall W1. Further, in the drawing, the stabilizing liquid stirrer 3 is configured so that the drive shaft 15 thereof is oriented in the vertical direction. However, the lower end may be inclined so as to face the new end surface.

In addition, since the solidification material injection pipe 2 is usually a pipe made of vinyl chloride and cannot be expected to have sufficient strength, in this embodiment, the load of the stabilizing liquid stirrer 3 is
Is provided with a hanging string connecting portion 17 and received by the hanging string 18 shown in FIG.
The connecting arms 16 and 16 were fixed to such an extent that the positions could be mainly maintained.

[Effects of the Invention] Since the present invention is as described above, even if a mud cake M 'is formed on a new section, the mud cake M' is sequentially peeled off by the stabilizing liquid stirrer 3 and newly formed with the existing basement wall W1. It is possible to provide an underground continuous wall construction method capable of constructing a continuous underground wall having excellent waterproofness and integrity without interposing a layer of mud cake M ′ between the underground wall W2 and the underground continuous wall W2.

[Brief description of the drawings]

1 is a plan view of a continuous underground wall being drilled by the method of the present invention, FIG. 2 is a longitudinal sectional view, FIG. 3 is a sectional view of a connecting portion of the continuous underground wall, and FIG. 4 is used in the present invention. It is a partial section front view showing an example of a stable liquid stirrer. DESCRIPTION OF SYMBOLS 1 ... Trench 2 ... Solidified material injection pipe 2a ... Lower end opening 3 ... Stabilized liquid stirrer M ... Stabilized liquid, S ... Solidified material

Claims (1)

(57) [Claims] 1. After a trench 1 having a predetermined depth is drilled while being filled with a stabilizing liquid M, a solidification material injection pipe 2 is inserted into the trench 1, and the solidification material injection pipe 2 is pulled up while opening the lower end thereof. In the underground continuous wall method in which the solidified material S is injected from the solidified material injection pipe 2, a stable liquid stirrer 3 is fixed to a lower portion of the solidified material injection pipe 2, and the solidified material S is injected from the lower end opening 2 a of the solidified material injection pipe 2.
At the lower end opening by the stabilizing liquid stirrer 3
Underground continuous wall method characterized by stirring the stable liquid layer above 2a.