JP2001090073A - Placing method for underwater concrete using light- weight aggregate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the jumping-out of light-weight aggregate, so that underwater scattering of fresh concrete can be prevented. SOLUTION: In the placing method for underwater concrete using light-weight aggregate, a tabular body 5 composed of a mesh material is arranged previously near the top end of underwater concrete 4 when underwater concrete 4 is placed by using a tremie pipe 3. When concrete is placed by the tremie pipe 3 under such a state, the rise of light-weight aggregate rising in underwater concrete 4, particularly light-weight aggregate as coarse aggregate is inhibited by the tabular body 5, and there is no possibility that underwater concrete 4 jumps out into water from the top end of underwater concrete.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete casting method for constructing an underwater structure such as a footing or caisson of a bridge with underwater concrete using lightweight aggregate.

[0002]

2. Description of the Related Art When building footings or caissons for bridges, so-called underwater concrete is often used. However, if the ground at the construction site is soft, it is necessary to minimize the ground improvement work. It is desirable to make the basic structure such as footing or caisson as light as possible.

On the other hand, in order to reduce the weight of concrete, it is common to use lightweight aggregate.

[0004]

However, when the underwater concrete is cast using the lightweight aggregate, the lightweight aggregate having a small specific gravity rises in the fresh concrete during the casting of the concrete, and when the concrete is lighter than the water, However, there is a risk that the fresh concrete may jump out of the water and float up in the water, and at that time the fresh concrete may fly into the water and pollute the surrounding water area.

[0005] For this reason, the use of underwater concrete using an aggregate is generally inevitable, and as a result, there has been a problem that it is almost impossible to reduce the weight of the foundation structure.

The present invention has been made in view of the above circumstances, and provides a method of casting underwater concrete using a lightweight aggregate capable of preventing the light aggregate from flying out and, hence, preventing the fresh concrete from scattering underwater. The purpose is to do.

[0007]

In order to achieve the above object, a method for casting underwater concrete using a lightweight aggregate according to the present invention is as described in claim 1. When a steel sheet is cast into a predetermined casting area via a concrete supply pipe such as a tremy pipe, a plate made of a mesh material is arranged near the top of the underwater concrete.

[0008] In the method of placing underwater concrete using lightweight aggregate according to the present invention, a buoyancy adjusting material is attached to the plate-like body.

In the method for casting underwater concrete using a lightweight aggregate according to the present invention, an anchor embedded in the underwater concrete is protruded from a lower surface of the plate-like body.

In the method for casting underwater concrete using lightweight aggregate according to the present invention, underwater concrete using lightweight aggregate is cast into a predetermined casting area via a concrete supply pipe such as a tremy tube. At this time, a plate made of mesh material is placed near the top of underwater concrete.

According to the present invention, even in the conventional case, even in a situation where the lightweight aggregate jumps out of the fresh concrete and floats in the water due to its lightness, the present invention does not require the vicinity of the top end of the underwater concrete. Since the plate-like body made of mesh material is arranged in the lightweight aggregate that has risen in fresh concrete, even if it receives buoyancy from the surrounding mortar component, the rise is suppressed at the lower surface of the mesh material,
There is no danger of jumping out of the top of the underwater concrete.

A concrete supply pipe such as a tremee pipe may be passed through a through-hole provided in the plate-like body, or may be passed through a through-hole provided in a form surrounding the casting area. .

The plate-like body made of the mesh material is disposed near the top end so that the lightweight aggregate in the underwater concrete does not jump out of the underwater concrete into the water.
When the top of the underwater concrete rises with the progress of the casting operation, the state is maintained near the top of the underwater concrete without separating from the top and sinking deeply into the underwater concrete. Need to be
As long as it has such a function, the structure and the shape are arbitrary.

It should be noted that the arrangement near the top of the underwater concrete means that the concrete is placed on the top so as to cover the top of the underwater concrete, or that the concrete is buried at a position slightly lower than the top. It shall include the case where it is arranged.

The mesh material constituting the plate-like body may be appropriately considered in consideration of the minimum size of the lightweight aggregate, particularly the coarse aggregate.

Here, if the buoyancy adjusting material is attached to the plate-like body, the size, material, mounting position and the like of the buoyancy adjusting material are appropriately adjusted so that when the top of the underwater concrete rises, the plate-like shape is adjusted. The entire body can be easily held in the vicinity of the top end position without being separated from the top end of the underwater concrete and without being sunk into the underwater concrete.

If an anchor embedded in the underwater concrete is protrudingly provided on the lower surface of the plate-like body, the anchor receives an adhesive force from the underwater concrete, so that the plate-like body is separated from the top end of the underwater concrete. , Can be prevented from tilting.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for placing underwater concrete using lightweight aggregate according to the present invention will be described below with reference to the accompanying drawings. It is to be noted that the same reference numerals are given to components and the like that are substantially the same as those in the conventional technology, and description thereof will be omitted.

FIG. 1 is a construction procedure diagram showing a case where the method of placing underwater concrete using lightweight aggregate according to the present embodiment is applied to placing underwater concrete in a caisson, and FIG. It is the perspective view which showed the shape and the arrangement condition.

First, a caisson 1 is installed as shown in FIG. 1 (a) prior to casting of underwater concrete using a lightweight aggregate. When installing the caisson 1, the caisson 1 is towed to the site, the caisson installation location is excavated flat in advance, and then the caisson 1 is submerged on the seabed 2 by pouring water into the caisson 1. .

Next, as shown in FIG. 2 (b), the lower end of the tremy tube 3 which is a concrete supply pipe is inserted into the pre-cast underwater concrete 4, and in this state, the inside of the caisson 1 is drained while draining. Caisson 1 through tube 3
The underwater concrete 4 is cast in the casting area in the inside. In the method of casting the underwater concrete 4 according to the present embodiment, when such underwater concrete 4 is cast, as shown in FIG. The plate-like body 5 made of the material is placed near the top end of the underwater concrete 4, and the tremy tube 3 is inserted into a through hole 23 formed in the mesh material.

The mesh material constituting the plate-like body 5 is a lightweight aggregate 2
In consideration of the minimum size of the lightweight aggregate, particularly the coarse aggregate, FIG.
As shown in (b), for example, it is preferable to set the aperture to about 5 to 10 mm.

When the top of the underwater concrete 4 rises with the progress of the casting operation, the plate-like body 5 does not separate from the top and does not become deeply buried in the underwater concrete 4 and does not immerse in the underwater concrete 4. The weight and material may be appropriately set so as to be maintained in the state of being held near the top end of the concrete 4 (FIG. 2B), and may be appropriately selected from reinforcing steel and plastic materials.

As can be seen in FIG. 2B, a number of anchors 22 embedded in the underwater concrete 4 are protruded from the lower surface of the plate-like body 5, and the adhesive force received from the underwater concrete 4 causes the top of the underwater concrete 4. The plate-like body 5 is prevented from being separated or inclined from the end.

The plate-like body 5 is disposed so as to be arranged on the entire top of the underwater concrete 4 cast in the caisson 1.
It is preferable that the inner diameter of the caisson 1 is substantially equal to or slightly smaller than that of the caisson 1. In addition, it is not necessary to constitute integrally, and you may make it comprise the whole by connecting many segments planarly.

When the concrete is cast by the tremy tube 3 in a state where the plate-like body 5 is arranged near the top end of the underwater concrete 4 (FIG. 3), conventionally, the lightweight aggregate becomes lighter. Therefore, even in a situation where the plate-like body 5 made of a mesh material is disposed near the top end of the underwater concrete 4 in the present embodiment, even in a situation where the plate-like body 5 is made of fresh concrete, As shown in FIG. 3, the lightweight aggregate that has risen in the underwater concrete 4, particularly the lightweight aggregate 21 that is coarse aggregate, rises on the lower surface of the plate-like body 5 even if it receives buoyancy from the surrounding mortar component. The appearance of the underwater concrete 4 is eliminated, and there is no possibility that the underwater concrete 4 jumps out into the water.

As described above, according to the method for placing underwater concrete using the lightweight aggregate according to the present embodiment,
Since the concrete placement by the tremy tube 3 is performed in a state where the plate-like body 5 made of the mesh material is arranged near the top end of the underwater concrete 4, the lightweight aggregate that has risen in the underwater concrete 4 that is fresh concrete There is no danger that the 21 will jump out of the top of the underwater concrete 4 into the water.

Therefore, it is possible to prevent the light-weight aggregate 21 from jumping out and the resulting underwater scattering of fresh concrete, and consequently the contamination of the surrounding water area, and as a result, it is possible to prevent the light-weight aggregate from being used in the underwater concrete. It is also possible to reduce the weight of the basic structure. In addition, by preventing the light-weight aggregate 21 from jumping out, in other words, preventing the aggregate from being separated, the quality of the underwater concrete can be improved, and it becomes possible to construct a homogeneous and dense concrete.

Further, according to the method of casting underwater concrete using lightweight aggregate according to the present embodiment, the anchor 22 embedded in the underwater concrete 4 protrudes from the back surface of the plate-like body 5, so that the anchor can be used. Due to the adhesive force received from the underwater concrete 4, the plate-like body 5 can be prevented from being separated or inclined from the top end of the underwater concrete 4.

Further, according to the underwater concrete casting method using the lightweight aggregate according to the present embodiment, the plate-like body 5 also serves to press and compact the underwater concrete 4 by its own weight.

In this embodiment, the tremy tube 3 is used as the concrete supply pipe. Instead, as shown in FIG. 4, concrete is inserted into the through hole 32 formed in the side wall as the mold of the caisson 1. The pipe 31 may be connected, and underwater concrete pumped from a concrete pump (not shown) may be poured into the caisson 1 via the concrete pipe.

Although not particularly mentioned in the present embodiment, a buoyancy adjusting member 41 may be attached to the plate 5 as shown in FIG.

In this configuration, when the top of the underwater concrete 4 is raised, the entire plate 5 is moved from the top of the underwater concrete 4 by appropriately adjusting the size, material, mounting position, and the like of the buoyancy adjusting material 41. It is possible to hold the sheet in the vicinity of the top end position without being separated and without being deeply sunk into the underwater concrete 4.

[0034]

As described above, according to the method of casting underwater concrete using the lightweight aggregate of the present invention, the lightweight aggregate that has risen in the underwater concrete, which is fresh concrete, can be used as the top of the underwater concrete. There is no danger of jumping out of the water. Therefore, it is possible to prevent the light aggregate from jumping out and the accompanying splash of fresh concrete in the water, and consequently the pollution of the surrounding water area. As a result, the underwater concrete using the lightweight aggregate can reduce the weight of the foundation structure. It is also possible to achieve the conversion.

According to the second aspect of the present invention, when the top of the underwater concrete is raised, the entire plate is separated from the top of the underwater concrete. There is also an effect that it can be held near the top end position without being deeply immersed in the underwater concrete.

Further, according to the method of placing underwater concrete using the lightweight aggregate according to the third aspect of the present invention, the plate-like body is prevented from being separated or inclined from the top end of the underwater concrete. It also has the effect that it can be done.

[0037]

[Brief description of the drawings]

FIG. 1 is a construction procedure diagram showing a state in which underwater concrete is poured into a caisson according to a method of placing underwater concrete using lightweight aggregate according to the present embodiment.

FIGS. 2A and 2B are diagrams of a plate-like body used in the casting method according to the embodiment, wherein FIG. 2A is a perspective view showing an arrangement state, and FIG.

FIG. 3 is a cross-sectional view showing the operation of the underwater concrete placing method using the lightweight aggregate according to the embodiment.

FIG. 4 is a cross-sectional view of a method for casting underwater concrete using a lightweight aggregate according to a modification.

FIG. 5 is a cross-sectional view of a method for placing underwater concrete using a lightweight aggregate according to another modification.

[Explanation of symbols]

Reference Signs List 3 Toremy pipe (concrete supply pipe) 4 Underwater concrete 5 Plate body 21 Light aggregate 22 Anchor 31 Concrete pipe (concrete supply pipe) 41 Buoyancy adjusting material

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ryo Shinmura 2- 15-2 Konan, Minato-ku, Tokyo Obayashi Gumi Tokyo Head Office (72) Inventor Akihiro Hattori 2- 15-2 Konan, Minato-ku, Tokyo Obayashi Corporation Tokyo head office F-term (reference) 2D045 AA04 BA05 CA11

Claims (3)

[Claims] When an underwater concrete using a lightweight aggregate is cast into a predetermined casting area via a concrete supply pipe such as a tremie pipe, a plate-like body made of a mesh material is placed near a top end of the underwater concrete. A method for placing underwater concrete using lightweight aggregate, characterized by being placed in a concrete area. 2. The method according to claim 1, wherein a buoyancy adjusting material is attached to the plate-like body. 3. The method according to claim 1, wherein an anchor embedded in the underwater concrete is protruded from a lower surface of the plate-like body.