JPH07100937B2 - Construction method of joint part in continuous underground wall method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of constructing a joint portion in a continuous underground wall method.

<Conventional technology> As is well known, the continuous underground wall method excavates a slot hole in the ground, inserts a rebar cage into the slot hole, and then places concrete to form the panel wall. It is a construction method in which other panel walls are sequentially formed on the side of this panel wall, and it is constructed as a retaining wall for an underground structure or a main body wall of an underground tank.

The weak point of the wall constructed by this type of construction method is the joint between the panel walls, and ensuring the integrity of this part is an important technical issue. It becomes more important when used as a wall.

By the way, as a construction method of the joint portion of the continuous underground wall, for example, the following construction method is proposed in JP-B-45-35621.

The method of constructing the joint part shown in this publication is that the joint box frame is attached to the end of the rebar cage and the joint part of the panel wall is made watertight to prevent non-casting of concrete. Form a part, root the inside after building a predetermined panel wall,
The exposed side surface of the joint box frame is cut and removed, the reinforcing bar cages are connected between the panel walls, and concrete is placed in the non-placed portion.

However, such a joint portion construction method has technical problems described below.

<< Problems to be Solved by the Invention >> That is, in the method of constructing a joint portion disclosed in the above publication, the panel walls are connected until the inside is cut and concrete is placed in the joint portion. Not so, especially when building to high depths, there is a problem with its stability.

In order to solve this stability problem, for example, applying the reverse winding method adopted in the construction of the underground tank, it is possible to partially construct the joint portion from the ground side,
In this case, not only is the supporting structure of the reverse winding formwork complicated, but there is also the problem of the integrity of the joint portion in the horizontal direction of the joint portion.

The present invention has been made in view of such conventional problems, and an object of the present invention is to easily perform construction while avoiding complication of a supporting structure of a formwork and a horizontal joint portion. It is to provide a method of constructing a joint portion in a continuous underground wall construction method capable of ensuring a strong unity.

<Means for Solving the Problem> In order to achieve the above object, the present invention excavates a slot hole in the ground, inserts a rebar basket in the slot hole, and then places concrete to form a panel wall. In the continuous underground wall construction method to form and connect other panel walls sequentially to the side of this panel wall,
A box joint is attached to the end of the rebar cage, and gravel is filled into the box joint to form a non-casting portion of the concrete in the joint between the panel walls, and the predetermined panel When root-cutting the inside after building the wall, the exposed part of the box joint and the gravel inside are removed from above as the root-cutting proceeds, and a flexible sheet is laid on the remaining gravel. The concrete for the joint portion is cast, and the joint portion is sequentially connected from the upper side to the lower side.

<< Advantageous Effects of the Invention >> According to the method of constructing the joint portion in the continuous underground wall construction method of the above configuration, when concrete is poured to form the joint portion from the upper side to the lower side, it is exposed by root cutting It is enough to remove a part of the box and gravel, lay a flexible sheet on the remaining gravel, and install a formwork on a flat plate between adjacent panel walls. The support structure does not become complicated.

In addition, when the joint part for one step is constructed, the lower gravel is removed and the flexible sheet is peeled off, the unevenness of the gravel is transferred to the lower surface of the constructed joint part and roughened. As a result of this, the horizontal joining unit becomes more integral.

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

1 and 2 show an embodiment of a method of constructing a joint portion in the continuous underground wall construction method according to the present invention.

In the construction method shown in the figure, first, a rectangular slot 10 is excavated to a predetermined depth in the ground, and a rebar cage 12 is built in the excavation hole 10.

A box joint 17 composed of a pair of side plates 13 and 14 and a partition plate 15 and a pull-out plate 16 is preliminarily integrally attached to the end of the rebar cage 12, and the horizontal bar 18 of the rebar cage 12 is a partition. It penetrates the plate 15 and projects into the box joint 17.

Further, on the inner surface side of the partition plate 15, a split water blocking plate 19 having a length of about half the total length is provided in a protruding manner.

When the insertion of the rebar cage 12 into the predetermined position is completed, the box joint 17 is filled with the gravel 20.

At this time, the gravel 20 prevents the box joint 17 from being deformed by surrounding earth pressure, and also prevents the rebar cage 12 from moving due to the placing pressure of concrete.

When the filling of the gravel 20 is completed, concrete is placed on the inside of the box joint 17, and the concrete is hardened to cure the concrete, as shown in FIGS. 1 (A) and 2 (A).
22 is formed.

Next, the same groove hole 10a as the above is excavated on the side of the preceding panel 22, the rebar cage 12a is built in the groove hole 10a, and the gravel 20 is filled in the box joint 17a again, and concrete is poured. As a result, the trailing panel wall 22a is formed.

As a result, as shown in FIG. 1 (B) and FIG. 2 (B), a concrete non-casting portion is formed in the joint portion 24 between the leading and trailing panel walls 22, 22a, and thereafter, as described above. The same work is repeated.

When a predetermined number of panel walls are constructed in a ring shape or a rectangular shape, the earth and sand inside the wall are excavated and root cutting is performed.

At this time, in the present embodiment, as the root cutting progresses, the joint portions 24 are sequentially connected from top to bottom.

In forming the joint portion 24, first, when root cutting is performed to a predetermined depth, the box joints 17, 1 exposed to that depth are obtained.
The side plates 14, 14a and the gravel 20 inside the 7a are removed.

At this time, the pull-out plates 16 and 16a are removed if they can be pulled out, and if they are difficult to pull out, they are partially melted and removed.

Then, the remaining split water-stop plates 26, 26a are made to correspond to the positions of the split water-stop plates 19, 19a fixed to the partition plates 15, 15a, respectively.
Is welded, and the horizontal bar of the reinforcing bar 28 for connection is connected between the horizontal bars 18, 18a protruding from the partition plates 15, 15a by a mechanical joint or welding.

Then, a flexible sheet 30 is laid on the remaining gravel 20, a form 32 on a flat plate is installed between the side surfaces of the leading and trailing panel walls 22, 22a, and concrete is poured. Joint part 24
Form one step.

In this case, the vertical bar of the reinforcing bar 28 may penetrate the flexible sheet 30 and be projected into the gravel 20 below in order to secure the connection with the next step.

When the cast concrete hardens, root cutting work is performed again, and the sheet 30 is removed with the exposed side plate 15 removed.
The gravel 20 below is removed, and the sheet 30 is removed and diverted.

After this, by repeating the above work according to the progress of root cutting, a joint portion is formed over the entire length between the leading and trailing panel walls 22, 22a, and a joint portion is formed between each panel wall. A continuous continuous underground wall is constructed by.

Now, when the joint portion is constructed by the method as described above, when concrete is poured to form the joint portion 24 from the upper side to the lower side, the side plate 14 of the box joint 17 exposed by root cutting is exposed.
And a part of the gravel 20 is removed, a flexible sheet 30 is laid on the remaining gravel 20, and a flat form 32 is installed between the adjacent panel walls 22 and 22a. Since it is good, the supporting structure does not become complicated unlike the reverse winding formwork.

Further, when the joint portion 24 for one step is constructed, the lower gravel 20 is removed and the flexible sheet 30 is peeled off, the joint portion constructed.
Since the unevenness of the gravel 20 is transferred to the lower surface of 24 to be in a roughened state, the integrity of the horizontal joining portion is strengthened.

The concrete to be poured into the joint portion 24 may be a normal mixture, but it is desirable to add an admixture such as a shrinkage-reducing agent in order to ensure the integrity of the concrete in the joint portion.

The material of the flexible sheet 30 is not limited as long as the concrete does not leak, but the contact surface with the concrete may be impregnated with a solidification retarder.

[Brief description of drawings]

1 and 2 show an embodiment of a method of constructing a joint portion according to the present invention. FIG. 1 is a longitudinal sectional view showing the construction procedure in order, and FIG. 2 is a plan view of FIG. It is a figure. 10,10a …… Slot 12,12a …… Reinforcing bar cage 17,17a …… Partition plate 20 …… Gravel 22 …… Preceding panel wall 22a …… Back panel wall 30 …… Flexible sheet

Claims (1)

[Claims] 1. A trench hole is excavated in the ground, a reinforcing bar cage is inserted into the trench hole, and then concrete is placed to form a panel wall, and another panel wall is sequentially formed on the side of this panel wall. In the continuous underground wall method of forming a connection, a box joint is attached to the end of the rebar cage, gravel is filled in the box joint, and the concrete between the panel walls is not cast. When the root of the interior is formed after forming the installed portion and the predetermined panel wall is constructed, the exposed portion of the box joint and the internal gravel are removed from above in accordance with the progress of root cutting, and remain. Laying a flexible sheet on the gravel and placing concrete for the joint portion, the joint portion is successively connected from the upper side to the lower side of the joint portion in the continuous underground wall method Construction method.