JPH0586618A - Treatment of cast-in-place concrete pile head - Google Patents

Abstract

PURPOSE:To easily crush the extra-banking portion even for large pile diameters by a method in which a container filled with a static breaking agent is set inside of main reinforcing bars corresponding to the lower end of an extra-banking portion, and the container is doubly attached to the inside adjacently to the main reinforcing bar. CONSTITUTION:A water-permeable container 10a filled with a static breaking agent is attached to the main reinforcing bar 2 of a reinforcing bar cage and a water- permeable container 10b is set inside of the radial direction of a pile pit 4 and fixed to the main bar 2 or the container 10a by a binding wire 3. In this case, the containers 10a and 10b are set on the places corresponding to the lower end of the extra-banking concrete, and the container 10b is doubly attached adjacently to the inside of the main bar 2. The edge of the main bar is attached to the main bar 2 of the reinforcing bar cage to prevent the adhesion of concrete, and in the presence of a stabilizer liquid, the pile pit 4 is excavated to a diameter of 1600mm or more. The cage is inserted into the pit 4 filled with stabilizer liquid, and concrete is placed while replacing the stabilizer liquid with concrete. During the curing of concrete, the extra-banking portion of concrete is broken at a preset position by the expansion of the static breaking agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pile head treatment method for cast-in-place concrete piles, more specifically a pile diameter of 1600 mm.
The present invention relates to a pile head treatment method for cast-in-place concrete piles that is preferably used in the above cases.

[0002]

2. Description of the Related Art So-called cast-in-place concrete piles have been conventionally used as foundation piles for building buildings and bridges by excavating pile holes on site and placing fresh concrete in the pile holes to form piles. More adopted. By the way, when forming such a pile, it is necessary to crush and remove the defective concrete in the pile head extra portion of the cast-in-place concrete pile. However, the conventional method of crushing and removing by using a breaker or the like has a problem of environmental degradation due to noise and vibration given to the neighborhood.

As a crushing and removing method without problems such as noise and vibration, a pile head treating method using a static crushing agent which is exothermicly expanded by hydration is known. In this construction method, as shown in FIG. 3, a container 1a filled with a static crushing agent is attached to a main bar 2 of a rebar cage with a binding wire 3 and the rebar cage is inserted into a pile hole 4 in that state. , The container 1a is immersed in a stabilizing liquid at the time of excavation, which is filled in the pile hole 4 in advance, and the moisture in the stabilizing liquid is brought into contact with the static crushing agent in the container 1a to expand the crushing agent and the concrete Is cast and cured, and then the pile head surplus portion of the cast-in-place concrete pile crushed by the expansion of the crushing agent is removed.

[0004]

However, in the pile head treatment method shown in FIG. 3, the pile head extra portion can be crushed and removed with sufficient accuracy up to a pile diameter of about 1500 mm, but the pile head excess of about 1600 mm or more can be removed. When the diameter is large, the crushing action of the crushing agent does not sufficiently function, the accuracy of cracks deteriorates, and it becomes difficult to crush and remove the extra portion with high accuracy.

Conventionally, in order to solve such a problem,
When the pile diameter is about 1600 mm or more, as shown in FIG. 4, a container 1a ... Filled with a static crushing agent is attached to the main bar 2 of the reinforcing bar cage in the same manner as in the example shown in FIG. Between the two or the main bar 2 ... Attached to the container 1a,
The rebars 5 are assembled between the la 1a, and the rebars 5 are attached to the container 1b inside the container 1a in the vicinity of the center of the pile hole 4, and the pile head extra portion is formed in the same manner as described above. Is being crushed and removed. However, in this case, the tremie pipe may collide with the container 1b in the vicinity of the center portion when pouring concrete, and when colliding, the container 2b ... However, there is a problem that the crushing effect cannot be obtained.

The present invention has been made in view of the above circumstances. An object of the present invention is to accurately crush and remove an extra heap portion even when treating a pile head of a cast-in-place concrete pile having a pile diameter of 1600 mm or more. It is to provide a pile head treatment method using a static crushing agent that can be used.

[0007]

In the pile head treatment method for cast-in-place concrete piles of the present invention, first, the static crushing agent is formed into granules, and the granules are filled into a water-permeable container. Inside the main bar at a position corresponding to the lower end of the pile head extra portion of the concrete of the reinforcing bar basket, it is mounted along the circumferential direction and at least double mounted in the radial direction of the pile hole, and among these containers The container on the center side is also mounted close to the main bar, and then the rebar cage is inserted into the pile hole to bring the container into contact with the stabilizing solution previously filled in the pile hole, and then the concrete is placed in the pile hole. Placing was used as a means for solving the above problems.

The present invention will be described in detail below. The pile head treatment method of the present invention is preferably adopted particularly when the pile diameter is a large diameter of 1600 mm or more. The static crushing agent used in the present invention is composed mainly of an expansive crushing agent which is exothermicly expanded by hydration of calcium oxide or the like, to which a known retarder or the like is added. The reason why the retarder is added is that the time required for the static crushing agent to develop the hydration expansion pressure can be adjusted to a desired time by appropriately adjusting the type and amount of the retarder added.

Further, as such a static crushing agent, one which has been previously formed into a granular shape is used. Here, the static crushing agent is made into granules by providing voids of an appropriate size between each particle so that the stabilizing liquid in the pile holes can sufficiently contact each particle as described later. This is because. As a method of molding the static crushing agent into granules, a method of continuously granulating the dry powder of the static crushing agent into a strong almond-shaped briquette by a briquetting machine or a compacting machine According to the method, dry powder of the crushing agent is preferably compression-molded into a plate shape with a smooth roll, and then crushed and granulated. However, other dry compression-molding methods can of course be used. Further, the size of the granules of the static crushing agent may be at least as large as forming voids that allow water to easily penetrate between the particles, for example, those having a particle size distribution shown in Table 1 below. Is preferred.

[0010]

[Table 1]

As a container for filling such a static crushing agent, a water-permeable container such as a tubular container is used. Here, as the water-permeable container, a container made entirely of a permeable material such as paper, or a part of the peripheral wall of the container or an opening made of a net made of a mesh that does not allow the crushing agent to slip out, etc. Is mentioned. That is, in such a container, the container itself has water permeability (water permeability).
By having water, or by allowing water to easily pass through the net portion, a water-permeable container is obtained. The container filled with the static crushing agent having such a structure easily absorbs moisture inside when contacted with the stabilizing solution as described later, and contacts the granular static crushing agent with the moisture. It is supposed to.

As the stabilizing liquid for preventing the peripheral wall of the pile hole from collapsing at the time of excavating the pile hole, bentonite solution or bentonite solution to which CMC or a dispersant is added is used. And, in order to make the static crushing agent in the container absorb such a stable liquid, it is sufficient to fill the stable holes in the pile holes, and the stable liquid is not sufficiently filled in the pile holes. In this case, the container may be submerged in the stabilizing liquid at the time of pouring the concrete so that the static crushing agent absorbs water.

Regarding the arrangement of the above-mentioned containers, as shown in FIG. 1, a water-permeable container 10a in which the main bars 2 of the reinforcing bar cage are filled with the static crushing agent in the same manner as in the example shown in FIG. The water-permeable container 10b is arranged on the inner side (center side) of the pile holes 4 from the container 10a, and the container 10b is connected to the main bar 2 or the container 10a by the binding line 3. Attach and fix. In this case, the containers 10a, 10b, ... Are located at positions corresponding to the lower ends of the pile head extra portions of the concrete to be formed,
It is double-mounted inside the main bars 2 of the rebar cage, and the container 10b on the center side is also mounted close to the main bars 2.

Container 10 filled with such a static crushing agent
In order to carry out the method for treating a pile head of a cast-in-place concrete pile of the present invention using a, 10b, ..., First, the pile hole 4 is excavated in the presence of a stabilizing liquid in the same manner as in the conventional method. The inner diameter of the pile hole 4 in this case is 1600 mm or more. Next, FIG.
As shown in FIG. 5, a rebar cage having the containers 10a, 10b ... Attached thereto in advance is prepared, and a main bar edge cutting material (not shown) is attached to the main bar 2 of the rebar cage so that concrete does not adhere to the main bar.

Next, this rebar cage is inserted into the pile hole 4 filled with the stabilizing solution and submerged. Then, the stabilizing solution becomes the container 10.
a, 10b ... Infiltrate into contact with the granular static crushing agent, and the static crushing agent starts to expand. Furthermore, the concrete is poured while replacing the stabilizing liquid with the concrete, and after the completion of the casting, the concrete is cured until the strength of the concrete is exhibited. Then, since the expansion of the static crushing agent has been completed during this time, when excavating the soil and performing root cutting,
The overfilled concrete is crushed at a preset position by the expansion force of the static crushing agent.

[0016]

EXAMPLES The present invention will be specifically described below with reference to examples. As shown in FIG. 2, the pile diameter L of the cast-in-place concrete pile is 3000 mm, and the depth d of the extra concrete is 80.
Construction was carried out as follows with 0 mm and cover concrete W of 140 mm.

First, a B-tube and an M-tube of NEW-CAB (trade name; manufactured by Sumitomo Cement Co., Ltd.) are attached to the rebar cage 13, and CAB (trade name; Sumitomo Cement Co., Ltd.) which is a kind of static crushing agent. Made) round spiral sheath tube 1
0a, 10b ... (maximum diameter 38 mm, length 400 mm) were filled, and as shown in FIG. It is needless to say that the CAB is used in the form of granules in advance. The openings of both ends of the spiral sheath tubes 10a and 10b were covered with a net to prevent the static crushing agent from falling out of the tubes and to allow water to easily penetrate into the tubes.

Next, this rebar cage was inserted into the pile hole 4, the spiral sheath tube was submerged in the stabilizing solution, and then concrete was poured. Then, after 10 days, when the soil was dug up, a crack of 0.8 cm to 2.5 cm was generated along the planned cutting line (the lower end of the pile head extra part of the concrete), which facilitated the pile head. It was possible to slice into several pieces and also to remove cover concrete.

[0019]

INDUSTRIAL APPLICABILITY As described above, according to the pile head treatment method for cast-in-place concrete of the present invention, the inside of the main bar at the position corresponding to the lower end of the pile head extra portion of concrete is filled with the static crushing agent. At least doubly install the water-permeable container in the radial direction of the pile hole, and also install the container on the center side of these containers close to the main bar, then insert it into the pile hole and statically crush the granules inside the container. Since the agent is brought into contact with the stabilizing solution filled in the pile holes in advance, the pile hole diameter is 160
Even with a large diameter of 0 mm or more, the crushing treatment of excess concrete can be easily performed by the hydration expansion of the static crushing agent, and also the tremie tube is prevented from colliding with the container on the center side. You can

[Brief description of drawings]

FIG. 1 is a plan view showing an arrangement of containers filled with a static crushing agent in a reinforcing bar cage used in a method for treating a pile head of a cast-in-place concrete pile of the present invention.

FIG. 2 is a side sectional view showing an embodiment of a construction method of the present invention.

FIG. 3 is a plan view showing an example of an arrangement of containers filled with a static crushing agent in a rebar cage used in a conventional pile head treatment method for cast-in-place concrete piles.

FIG. 4 is a plan view showing another example of the arrangement of the containers filled with the static crushing agent in the rebar cage used in the conventional pile head treatment method for cast-in-place concrete piles. 2 main bar 4 pile hole 10a, 10b container 13 rebar cage

Claims (1)

[Claims] 1. A reinforced concrete cage having a static crushing agent preliminarily inserted into a pile hole filled with a stabilizing solution at the time of excavation, and then concrete is placed to squeeze the pile head surplus portion of the concrete to the static crushing. In the pile head treatment method for cast-in-place concrete piles that are crushed by the hydration expansion action of the agent, first, the static crushing agent is formed into granules and filled in a water-permeable container, and this container is Inside the main bar of the reinforcing bar basket, the position corresponding to the lower end of the pile head extra part of the concrete,
It is attached along the circumferential direction and is attached at least doubly in the radial direction of the pile hole, and the container on the center side among these containers is also attached close to the main bar, and then the reinforcing bar cage is inserted into the pile hole and A pile head treatment method for cast-in-place concrete piles, characterized in that a container is brought into contact with a stabilizing solution previously filled in the pile holes, and then concrete is placed in the pile holes.