JPH02108728A - Method of sinking caisson - Google Patents

Abstract

PURPOSE:To make an applied load or a dead weight of a caisson smaller so as to easily and economically sink the caisson by press-fitting the caisson in a caisson box itself or a die frame already built in the upper part of a body section with a reaction force by use of jacks. CONSTITUTION:Press-fitting jacks 2 are extended, receiving a reaction force to an already built-up caisson box which is therefore press-fitted and sunk into the ground, and the ground below a working chamber 11 is excavated by means of an excavator 13. The muck thereof is scooped up by buckets 4 and discharged above the ground through a conveyer shaft 16. Then, a reinforcement, a die frame 52 and a gable die frame are assembled in a space 5 formed by the press-fitting of the body section 1 in such a condition that the jackets 2 are retracted, and concrete 6 is placed into the space 5 through a press-charge pipe 14 so as to build up an annular caisson box. Then, the jacks 2 are again extended to repeat the similar process so as to sink the caission. Further, the inclination of the caisson box is adjusted by manipulating the jacks 2, thereby it is possible to build a shaft which is not vertical.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a method for sinking a caisson.

<Conventional technology> In general, the method for sinking a caisson is to construct the foundation of the caisson in advance on the ground, excavate the ground below the working chamber provided at the lower end of the foundation, and sink the entire caisson using its own weight and load. is being carried out.

<Problems to be Solved by the Present Invention> The conventional caisson sinking techniques described above have the following closure points.

<B> When sinking a caisson, the surrounding frictional force with the ground,
Resistance such as buoyancy due to the pressure inside the work chamber acts.

Since these resistances increase as the sinking depth increases, conventional methods require a larger load as the sinking depth increases.

<Exposure> Also, for the same reason, it is necessary to make the caisson's own weight larger, which results in a structure that is larger than the design size as an earth retaining structure, which is uneconomical as the amount of excavation and occupancy increases.

<Object of the present invention> The present invention has been made to solve the above-mentioned problems.The load applied to the caisson and the caisson's own weight can be reduced, and the caisson can be sunk easily and economically. The purpose is to provide a method for sinking a caisson that can be carried out.

Configuration of the Present Invention> An embodiment of the present invention will be described below with reference to the drawings.

<A> Caisson body part As shown in FIG. 1, the caisson body part 1 of the present invention is a flat plate-shaped body with a working chamber 11 provided at the lower end and a cutting edge 12 protruding downward around the working chamber 11. It is a box.

Inside the work room 11, there are installed an excavator 13 for excavating the ground below the work room 11, a carry-out packet 14 for carrying the excavated earth and sand to the ground, an operation room 15 for operating these machines, and the like.

<Opening> Press-fitting jacks Press-fitting shirts 2 are a plurality of known jacks, such as hydraulic jacks, which are attached to the peripheral edge of the upper surface of the body part 1.

This press-fitting jack 2 is attached so that its telescopic rod can expand and contract in the vertical direction.

<C> Outer cylinder The outer cylinder 3 is a steel cylinder that surrounds the entire press-fit jack 2 and is attached so that the axis of the outer cylinder 3 is located on the same straight line as the axis of the caisson.

This outer cylinder 3 needs to have a length L that allows at least one lift of concrete to be poured above the upper end of the telescoping rod when the press-fit shirt V-2 is in a contracted state.

<Method for sinking a caisson> Using the device configured as described above, the caisson is sunk as follows.

l B> Press-fitting of the body part Taking the reaction force to the already built caisson box, extending the press-fitting jack 2, press-fitting the body part 1 into the ground and sinking, and excavating the ground below the work chamber 11 with the excavator 13. do.

Excavation can be carried out without water by supplying compressed air into the working chamber 11.

The excavated earth and sand is scooped up by a carry-out packet 14 and discharged to the ground through a carry-out shaft 16 provided in the center of the caisson.

In addition, by injecting the backfill material 4 between the ground and the frame part 1 when the frame part 1 is press-fitted, it is possible to reduce loosening with respect to the surrounding ground and increase the surrounding frictional force. .

<Opening> As shown in FIG. 2, in the annular pouring space 5 above the periphery of the frame formed by press-fitting concrete into the frame 1, reinforcing bars 51 are inserted into the mold with the press-fitting jack 2 contracted. Frame 52, wife formwork 53
Assemble.

Next, concrete 6 is poured into the pouring space 5.

Build a circular caisson box.

When pouring the concrete 6, it is preferable to press the concrete 6 into the pouring space 5 using a press-fit W54 attached to the formwork 52.

<C> Jack reaction force After placing the concrete 6, the press-fitting jack 2 is extended again and the frame part 1 is press-fitted into the ground.

At this time, the reaction force of the press-fitting jack 2 can be absorbed by the hardened concrete 6 above the peripheral edge of the frame.

At this time, it is preferable to connect and bury a reaction force receiving rod 55 in the concrete 6, as shown in FIG.

In addition, as shown in FIG.
It is also conceivable that the concrete 6 is compressed by a press jack 7 by taking the reaction force.

Repeat the above steps to complete the caisson sinking work.

<Effect> The present invention has the following effects.

(1) The caisson is press-fitted by the press-fitting jack 2, and the reaction force of the press-fitting jack 2 can be taken up by the already built caisson box itself above the frame 1 or by the formwork 52.

Therefore, the caisson can be press-fitted with a smaller load compared to press-fitting using a ship's load.

(2) The caisson frame portion 1 is a flat box.

Therefore, the weight can be reduced, and the design thickness can be reduced.

(3) When sinking the caisson, only the cutting edge 12 moves by press-fitting, so the amount of disturbance to the surrounding ground can be reduced.

(4) Since the press-fitting direction of the caisson can be controlled by operating the press-fitting jack 2, the inclination of the box can be corrected.

Furthermore, as shown in FIG. 3, if there is an obstacle 8 or the like on the ground, it is possible to construct a vertical shaft by operating the press-fitting jack 2.

<Effects of the Present Invention> Since the present invention has been described above, the following effects can be expected.

<B> When sinking a caisson, the surrounding frictional force with the ground,
Resistance such as buoyancy due to the pressure inside the work room works (.

These resistances increase as the sinking depth increases, so conventionally, a larger load was required as the sinking depth increased.

In contrast, in the present invention, the caisson is press-fitted by jacks, and the reaction force of the jacks can be taken up by the already built caisson box itself or the formwork, which is the upper force on the frame.

Therefore, compared to the conventional method of press-fitting the entire frame using the ship's load, the present invention has a partial press-fit structure in which only the tip is press-fitted, so the caisson can be easily press-fitted with a small load.

Furthermore, in the past, for the same reason, it was necessary to increase the weight of the caisson, which resulted in a structure that was larger than the design size for earth retaining, which was uneconomical due to the large amount of excavation and area occupied.

However, in the present invention, only the frame portion is press-fitted, and the annular caisson box is not press-fitted.

Therefore, the weight can be reduced, and the design thickness can be reduced.

Therefore, the amount of excavation is reduced and it is economical.

? C) In the present invention, only the cutting edge of the caisson is press-fitted and moved, so the amount of disturbance to the surrounding ground can be reduced.

l2> Since the present invention allows the direction of press-in of the caisson to be controlled by operating the jack, it is easy to correct the inclination of the box;
It is also possible to construct non-vertical shafts.

[Brief explanation of the drawing]

Figure 1: An explanatory diagram of an embodiment of the present invention. Figure 2: An enlarged explanatory diagram of the vicinity of the concrete placement space. Figure 3: An explanatory diagram of the construction of a vertical shaft.

Claims (1)

[Claims] (1) A plurality of jacks that are vertically expandable and retractable are attached to the upper peripheral edge of the caisson frame with a working chamber at the lower end, and around these jacks is a steel structure whose axis is colinear with the axis of the caisson. The caisson frame is press-fitted into the ground by the extension of the jack, and the reinforcing bars and formwork are assembled in the space above the periphery of the frame formed by the press-fitting of the caisson frame, with the jack retracted. Concrete is poured, then the reaction force is applied to the hardened concrete or formwork above the periphery of the caisson frame, the jack is extended and the caisson frame is pressed into the ground again, and the above steps are repeated to complete the caisson. How to sink a caisson.