JPS6160206B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction method for hollow large-diameter cast-in-place piles having a reinforced concrete structure.

Conventionally, when constructing hollow large-diameter cast-in-place piles, concrete is poured by inserting an inner formwork that has the strength and rigidity to withstand concrete lateral pressure inside a reinforcing bar cage built in a shaft. Therefore, the inner formwork is often buried, which is not economical.

Another method is known in which a flexible bag is inserted as the inner formwork and fluid is injected into the bag, but the construction is complicated as it requires post-casting of the bottom concrete.

The present invention was developed to solve the above-mentioned conventional problems, and details thereof will be explained below with reference to illustrated embodiments.

First, a standpipe 1 is erected, and the entire section of the shaft A is excavated using the excavator 2 using the muddy water construction method.

Next, the cylindrical reinforcing bar cage 3 is suspended and erected into the pit A using a crane or the like. In this case, the reinforcing bar cages 3 can be added one after another. Furthermore, vertical linear guides 4 such as thin reinforcing bars or ropes are provided at intervals in the circumferential direction inside the reinforcing bar cage, and a bowl-shaped bottom mold that is fixed to the reinforcing bar cage 3 is provided at the bottom of the guide 4. A frame 5 is provided.

Next, while inserting the flexible pressure vessel 6 inside the reinforcing bar cage 3, the injection hose 7 is inserted into the pressure vessel 6.
Inject the fluid by, for example,

The pressurized container 6 is made of rubber, synthetic resin, synthetic fiber, thin metal plate, etc., and is equipped with an upper lid 8 and a pressure gauge 9 as necessary.
etc. will be established. Water, muddy water, air, etc. are injected as fluid and pressurized. After inserting the pressure vessel 6, fluid is injected under pressure using a pump or compressor.

Next, the concrete 1 is passed through the tremie pipe 10.
1 is cast so as to bury the reinforcing bar cage 3 on the outer periphery of the pressure vessel 6 in the shaft A. After the concrete 11 hardens, the pressure vessel 6 is removed by removing the fluid, thereby completing the pile.

The present invention has the above-described configuration, and a hollow concrete pile can be cast on-site using a pressure vessel into which a fluid is injected as an inner formwork. Since the pressure vessel is flexible, removing the fluid facilitates demolding and enables reuse.

Further, by providing vertical linear guides at intervals in the circumferential direction inside the cylindrical reinforcing bar cage, insertion of the pressure vessel is facilitated, and eccentricity after pressurization due to concrete placement can be prevented. In addition, buoyancy acts on the bottom surface of the pressure vessel due to concrete pouring, and there is a risk that the pressure vessel will float due to this buoyancy. Since it is inserted so as to be in contact with the frame, its positioning is reliable and the pressure vessel can be prevented from floating up.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, FIG. 3, and FIG. 4 are cross-sectional views showing an outline of the construction process of the present invention. A... Pit, 1... Stand pipe, 2... Excavator, 3... Rebar cage, 4... Guide, 5... Bottom formwork, 6... Pressure vessel, 7... Injection hose, 8... …
Upper lid, 9...pressure vessel, 10...tremie tube, 1
1...Concrete.

Claims (1)

[Claims] 1 A vertical hole is excavated in the ground, vertical linear guides are installed at intervals in the inner circumferential direction, and a bowl-shaped bottom formwork is attached to a reinforcing bar cage at the bottom of the guide. A shaped reinforcing bar cage is built in the shaft, a flexible pressure vessel is inserted inside the cage so as to be in contact with the guide and the bottom form, and with fluid injected into the pressure vessel, the outside of the pressure vessel is 1. A method for constructing hollow large-diameter cast-in-place piles, the method comprising: pouring concrete to bury the reinforcing bar cage in the concrete, and removing the fluid in the pressure vessel after the concrete has hardened.