JPH1181305A - Removing method of concrete in underground concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely and rapidly crush concrete of an inferior part near the top end without noise and vibration and reduce the construction period. SOLUTION: In the removing method of a defective finish part D formed near a concrete C top end after the concrete C has been placed in a hole or a ditch excavated in the ground E and cured, one or more bar-shaped bodies 14 having a length corresponding to the thickness of the inferior part expected before the concrete C is placed or cured are driven from the top end of the concrete C. After it has been cured, the bar-shaped bodies 14 are drawn to form a hole 16. An expansive agent 18 us poured in the hole to give a static pressure toward the outside to the inner wall of the hole. In this way, the concrete C at the periphery of the hole 16 is crushed and removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an underground concrete structure obtained by substituting a chemical solution such as muddy water, such as an underground continuous wall or a cast-in-place pile. The present invention relates to a method for efficiently removing a site.

[0002]

2. Description of the Related Art For example, in the construction of an underground concrete structure such as an underground continuous wall or a cast-in-place pile, excavation is performed while filling a chemical solution such as muddy water from the surface of the ground to prevent collapse of a hole wall, and then rebar. Construction of baskets and casting of concrete are performed to construct underground concrete structures such as walls and piles in the ground. In this construction work, concrete is poured from the bottom of the hole (groove) to near the ground surface using a tremy pipe while replacing it with muddy water.

[0003] In general, after casting, a part of surplus water floats on the surface after casting, and the finished surface, which is called slime, does not solidify on the casting surface, or has extremely weak concrete strength even if solidified. Defective parts occur.

[0004] In particular, in this type of construction method, there is a case where the concrete placement depth is extremely large, and in addition, fine powder in the muddy water is attracted by replacement with the muddy water. The thickness tends to be large.

For this reason, after the construction of this kind of underground concrete structure, it is usual to remove the defective portion by removing the top end portion before constructing the upper structure.

[0006]

However, the conventional removing method by the hanging operation has the following technical problems. In particular, in the construction work of the underground diaphragm wall, the excavation site is generally partitioned by a pair of guide walls (also referred to as guide trenches) buried in the ground surface, and the inside is excavated vertically using the guide wall as a guide, Concrete is poured into the borehole, but the guide wall is often left as it is after construction.

[0007] Therefore, when performing hanging work in a state in which the guide wall cannot be removed, large machines cannot be used and manual work is mainly performed. Is not efficient and requires a great deal of trouble, and also causes noise, vibration and dust, so it is necessary to carry out the work while paying attention to the surrounding environment and the health of workers. Had become.

The method of the present invention has been made in order to solve the above-mentioned problems, and an object thereof is to crush concrete in a defective portion near the top end quickly and without generating noise or vibration. It is an object of the present invention to provide a method for removing concrete from an underground concrete structure capable of shortening the construction period.

[0009]

Means for Solving the Problems In order to achieve the above object, according to the first aspect of the present invention, concrete is poured into a hole or a groove excavated in the ground, and the concrete is solidified. After that, a method of removing the defective portion formed near the top end of the concrete is a method of removing a rod-shaped body having a length corresponding to the expected thickness of the defective portion before the concrete is poured or before the concrete is solidified. One or more pieces are poured from the top of the concrete, and after solidification of the concrete, the rod is pulled out to form a hole, and then pressure is applied outward on the inner wall of the hole to reduce the concrete around the hole. It is characterized in that it is crushed and then removed. According to the method of the present invention, a large-sized machine is not required, and the surrounding concrete can be efficiently crushed according to the number of holes.

[0010] The invention according to claim 2 is characterized in that the pressure is applied by expansion of the expansive drug filled in the holes, and according to the present invention, the drug is applied to each hole. The crushing action can be performed by a simple operation of merely injecting water, and there is no generation of noise, vibration or dust as compared with the conventional hanging operation.

According to a third aspect of the present invention, the pressure is applied by the explosion of an explosive inserted into the hole, and according to the present invention, the crushing is performed in a relatively short time. Work can be done.

According to a fourth aspect of the present invention, the pressure is applied by a jack which is inserted into the hole and can be extended in a radial direction. There is no generation of vibration or dust, and the crushing operation can be performed in a relatively short time.

[0013]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIGS. 1 (a) to 1 (d) show an operation procedure when the removal method of the present invention is applied to an underground continuous wall. In the figure, a pair of left and right guide walls 10 having an inverted L-shaped cross section are buried in the surface of the ground E, and an excavation groove 12 is provided inside the guide wall 10.
Is formed, and concrete C is poured and filled into the excavation groove 12 to construct an underground continuous wall.

In the above description, the thickness D of the defective portion near the top of the concrete is roughly specified from empirical values according to the concrete casting depth, concrete material, used muddy water, and the like. Based on this, before casting or immediately after casting, and before solidification of the concrete C, as shown in (a), the length corresponding to the thickness of the defective portion D and having a predetermined diameter A round bar 14 is arranged and buried in a state of covering almost the entire thickness of the defective portion D.

If the round bar 14 is placed before the casting, the round bar 14 is congested with the means for fixing to the guide wall 10 and other equipment and machinery. It is preferable to be buried between them. The surface of the round bar 14 is preferably a smooth and smooth surface in consideration of the subsequent workability.

Although two round bars 14 are buried in the width direction in this embodiment, they are also arranged at equal intervals in a direction perpendicular to the plane of the drawing. In addition, the diameter and the arrangement interval of the round bar 14 are selected in consideration of crushing performance such as the body expansion rate of the expansive agent for concrete crushing described below.

Next, after the concrete is solidified, the round bar 14 is removed, and as shown in (b), an expanding agent 18 as a static pressure additive is sequentially injected and filled into the hole 16 thereof. As the intumescent agent 18, for example, a lime-based agent having a high body expansion rate at the time of solidification such as "Super Blister (trade name)" manufactured by Onoda Co., Ltd. or "Blyster (trade name)" manufactured by Onoda is preferable. .

Then, as the solidification reaction of the chemical 18 progresses, the chemical 18 expands in the radial direction, and as a result, presses the concrete C already solidified around the hole 16, and the concrete strength is reduced at this portion. As shown in the figure, cracking progresses as shown in the figure because it is a lowered portion.

After completion of the final reaction of the drug 18,
As shown in (c), the individual pieces 20 are crushed. The drug 18 is similarly crushed and mixed in the strip 20. In addition,
After about 3 hours to 10 hours, the expansion reaction is completed, and after filling the hole 16, the concrete C is automatically crushed only by the static pressure resulting from the expansion without any trouble.

Therefore, after that, when the reinforcing bar or the like is not congested at the defective portion D, the strips 20 are sequentially removed using a heavy machine such as a power shovel having a shovel having a width corresponding to the groove width. By doing so, as shown in (d), only the portion with high concrete strength becomes the top end of the underground continuous wall.

After that, if necessary, fresh concrete is poured into a new top position to complete the finishing work.

In the above embodiment, the expansive drug is used as the static pressure applying body.
A jack with a smaller diameter than this and which can be expanded in the radial direction may be inserted, and the defective portion may be crushed by the expansion operation. Therefore, no dust or noise is generated during the operation, no consideration is required for the surrounding environment and workers, and especially in the case of a jack, the crushing operation can be completed in a relatively short time. Further, an explosive having a relatively small explosive power may be loaded into the hole 16 to perform the crushing operation. In this case, the crushing operation can be completed in a shorter time.

[0024]

As is apparent from the above description, the concrete removing method according to the present invention does not require a large machine for the crushing operation, and can efficiently crush the surrounding concrete according to the number of holes. It is effective for shortening the construction period.

When crushing work is performed by the static pressure of an inflatable chemical or a jack, there is no generation of noise, vibration and dust as compared with the conventional hanging work, so there is no adverse effect on the surrounding environment and the worker's health is reduced. It is also preferable from the viewpoint of management. Also, when explosives are used, the crushing operation can be completed in a short time, and the defective portion can be removed in a short time.

[Brief description of the drawings]

1 (a) to 1 (d) are explanatory sectional views showing a concrete removing procedure of the present invention.

[Explanation of symbols]

 Reference Signs List 12 excavation groove 14 rod-like body 16 drilling hole 18 expansive medicine E ground D defective part C concrete

Claims (4)

[Claims] 1. A method for casting concrete in a hole or a groove excavated in the ground, and after solidifying the concrete, removing a poor finish portion formed near a top end of the concrete, comprising: Before or before solidification of the concrete, one or more rods having a length corresponding to the thickness of the predicted failure site are driven in from the top of the concrete, and after the concrete is solidified, the rods are pulled out to form holes. A method for removing concrete in an underground concrete structure, comprising forming and then applying pressure outwardly on the inner wall of the hole to crush and remove the concrete around the hole. 2. The method for removing concrete in an underground concrete structure according to claim 1, wherein the pressure is applied by expansion of an expandable agent filled in the hole. 3. The method for removing concrete from an underground concrete structure according to claim 1, wherein the pressure is applied by an explosion of an explosive inserted into the hole. 4. The method according to claim 1, wherein the pressure is applied by a radially extending jack inserted into the hole.