JPH0410933B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a construction method for sinking a caisson consisting of a main caisson and a pile caisson underground.

[Prior art]

It is difficult to sink a large caisson into soft ground with a supporting layer at great depth until it reaches the supporting layer.
It is technically difficult and also uneconomical.

A caisson sinking method that can solve this problem is a method published in Japanese Patent Application Laid-open No. 75121/1983. In this construction method, a pile caisson consisting of a large number of small caissons is arranged along the periphery of a large main body caisson, a cover plate is fixed to the upper side of the first group of pile caissons, and the cover plate inside the pile caisson is fixed to the top of the first group of pile caissons. Compressed air is supplied between the soft ground and the main body caisson is supported via the pile caisson of the first group by the air pressure, and in this state, the pile caisson of the second group is supported by using the main body caisson as a reaction force support. is press-fitted into the ground, then a cover plate is fixed on the upper side of the second group of pile caissons, compressed air is supplied between the cover plate in the pile caissons and the soft ground, and the second group is The main caisson is supported through the pile caissons of the group, and in this state, the first group of pile caissons are press-fitted into the ground using the main caisson as a reaction force support, and then the main caisson is allowed to settle due to natural settlement or applied load. This is a construction method in which the above-mentioned process is repeated as many times as necessary to allow each group of pile caissons to reach the support layer, and then each pile caisson is connected to the main caisson.

[Problem that the invention seeks to solve]

However, in the case of the conventional submerged construction method, the cover plate is fixed to the pile caisson in an airtight manner and withstands air pressure using a large number of bolts and clips.
In addition, when removing the lid plate, it is necessary to remove a large number of bolts, so it takes a long time to attach and remove the lid plate, and furthermore, compressed air supply equipment is required, which increases the equipment cost. Further, if the main caisson does not sink naturally, it is necessary to load a large load on the main caisson, which is complicated.

[Purpose and structure of the invention]

The object of the present invention is to provide a caisson sinking method that can advantageously solve the above-mentioned problems. The process of press-fitting the pile caisson 2 into the ground using the main body caisson 1 as a reaction force support, and the process of press-fitting the main body caisson 1 into the ground using the pile caisson 2 as a reaction force support are repeatedly performed. It is based on the caisson sinking method.

〔Example〕

Next, the present invention will be explained in detail using illustrated examples.

When carrying out this invention and sinking a caisson consisting of a large main body caisson and a plurality of small pile caissons underground, first, as shown in FIG. After constructing a large concrete main body caisson 1 on soft ground 4, as shown in Figs. 2 and 3,
A plurality of anchor members 5 having steel rods are inserted and fixed to the ground 4 on both front and rear sides of the main body caisson 1, and pressure girders 6 extending in the front and back direction are placed on both left and right sides of the upper part of the main body caisson 1. The upper part of the anchor member 5 is inserted and locked into the hollow piston 8 of a center hole jack 7 placed and fixed on both ends of the pressurizing girder 6, and the center hole jack 7 moves the main body through the pressurizing girder 6. While applying a pressing force to the caisson 1, the lower ground inside the main caisson 1 is excavated and removed, and the main caisson 1 is lowered by an appropriate amount as shown in FIG.

Next, as shown in FIG. 4, a small concrete pile caisson 2 is inserted into the pile caisson insertion opening 3 in the middle part of the main body caisson 1 in the left and right direction, or the pile caisson 2 is inserted into the opening 3 in the main body caisson 1. A small concrete pile caisson 2 located within the main body caisson 1 is constructed, and then the lower ends of the vertical steel bars 9 placed on both sides of the pile caisson 2 are attached to the main body caisson 1.
A pressurizing girder 10 is mounted on the upper end of the pile caisson 2, and the pressurizing girder 1
Center hole jack 11 placed on the end of 0
The upper part of the steel rod 9 is inserted into the hollow piston 12 and locked, and the weight of the main body caisson 1 is used as a reaction force support, and the pile caisson 2 is pushed through the pressurizing girder 10 by the center hole jack 11. While applying a pressing force to the pile caisson 2, the lower ground inside the pile caisson 2 is excavated and removed, and the pile caisson 2 is press-fitted into the ground 4 as shown by the chain line in FIG.

As described above, after pressing an appropriate amount of pile caisson 2 into the ground 4 sequentially from each opening 3 arranged in the front and rear direction at the middle part of the main body caisson 1 in the left and right direction, as shown in FIG. The lower end of a steel rod 13 is removably connected to the upper end of the caisson 2, and the main caisson 1 is attached to each hollow piston 16 of a large number of center hole jacks 15 mounted on a pressurizing girder 14 at the upper end. The upper part of the steel rod 13 is inserted and locked, and using the weight of each pile caisson 2 as a reaction force support, a pressing force is applied to the main body caisson 1 via the pressurizing girder 14 by each center hole jack 15. , and while excavating the ground below the main body caisson 1, the main body caisson 1 is lowered by an appropriate amount as shown in FIG.

Repeat the press-in settling of the pile caisson 2 using the weight of the main body caisson 1 as a reaction force support as described above and the press-fit settlement of the main body caisson 1 using the weight of each pile caisson 2 as a reaction force support as many times as necessary. Then, as shown in FIG. 7, the lower end of each pile caisson 2 at the intermediate portion in the left-right direction is made to reach the support layer ground 17.

Next, as shown in FIG.
Insert a small concrete pile caisson 2 into the opening 3 in the main caisson 1, or
Small concrete pile caisson 2 located inside
Then, the lower ends of vertical steel bars 9 placed on both sides of the pile caisson 2 are connected to the lower part of the main body caisson 1, and the pressurizing girder 10 is mounted on the upper end of the pile caisson 2. The upper part of the steel rod 9 is inserted and locked into the hollow piston 12 of the center hole jack 11 placed on the end of the pressurizing girder 10, and the weight of the main body caisson 1 is used as a reaction force support. hand,
Pressurized girder 10 by the center hole jack 11
While applying a pressing force to the pile caisson 2 through Let it reach 17.

As described above, the pile caissons 2 are press-fitted into the ground 4 sequentially from the left and right openings 3 of the main body caisson 2, and the lower end of each pile caisson 2 is inserted into the support layer ground 17 as shown in FIG. After reaching , as shown in Figures 10 and 11,
A lid 18 is installed in the upper part of the pile caisson 2, and the male threaded portion at the lower end of the vertical reinforcing bar 20 is screwed into a large number of female threaded inserts 19 that are embedded and fixed in advance in the peripheral protrusion of the opening 3. After connecting the horizontal reinforcing bars 21 to the upper part of the vertical reinforcing bars 20, foundation concrete 22 is poured over an area slightly above the horizontal reinforcing bars 21 from the lid 18, and the upper part of each pile caisson 2 and the main body caisson 1 are connected. combine.

When the lower ends of the steel rods 9 and 13 are removably connected to the main body caisson 1 and the pile caisson 2, female threaded inserts are embedded and fixed in the main body caisson 1 and the pile caisson 2, and the steel rods 9 are inserted into the inserts. Then, a male thread may be screwed onto the lower end of the steel rod 13.

When carrying out this invention, the weight of the main body caisson 1 installed on the ground 4 is used as a reaction force support to press-fit each pile caisson 2 in the center in the left and right direction, and then each pile in the center The main body caisson 1 may be press-fitted using the weight of the caisson 2 as a reaction force support, and the same press-fitting process may be repeated thereafter. That is, the anchor member 5, the pressurizing girder 6, and the center hole jack 7 may be omitted, and the steps of first press-fitting the pile caisson 2 and then press-fitting the main body caisson 1 may be repeated as many times as necessary. Further, as a means for connecting the upper part of the pile caisson 2 to the main body caisson 1, any means other than those shown in the drawings may be adopted.

〔Effect of the invention〕

According to this invention, the pile caisson 2 is provided in the main body caisson 1 so as to be movable up and down, and the pile caisson 2 is press-fitted into the ground using the main body caisson 1 as a reaction force support, and the pile caisson 2 is used as a reaction force support. Since the process of press-fitting the main body caisson 1 into the ground is performed alternately, unlike the conventional method, there is no need to operate a large number of bolts to install and remove the cover plate, and there is no need to use compressed air supply equipment. Without carrying a large load, the body caisson 1 and the pile caisson 2 are alternately used to support the reaction force.
Moreover, the effect that the pile caisson 2 can be easily press-fitted can be obtained.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Figure 1 is a longitudinal sectional front view showing the main body caisson installed on the ground, and Figure 2 is a vertical sectional view showing the main body caisson in a state where it has been sunk to the ground by an appropriate amount. Figure 3 is a plan view of Figure 2, Figure 4 is a vertical front view of the pile caisson installed in the center of the main body caisson, with preparations for press-fitting completed, and Figure 5 shows the pile caisson. Figure 6 is a longitudinal front view showing the main body caisson settled by an appropriate amount, and Figure 7 is a front view showing the central pile caisson reaching the supporting layer ground. Figure 8 is a vertical front view showing the state in which the preparation for press-in of the pile caissons in the left and right direction has been completed, and Figure 9 is a vertical front view showing the state in which each pile caisson has reached the supporting layer ground. Figure 10 is a vertical sectional front view showing the state in which the main caisson and the pile caisson have been press-fitted and joined together, and Figure 11 is a vertical sectional front view showing an enlarged part of the joint between the upper part of the pile caisson and the main caisson. It is a diagram. In the figure, 1 is the main caisson, 2 is the pile caisson, 3 is the opening for inserting the pile caisson, 4 is the ground, and 5
is an anchor member, 6 is a pressure girder, 7 is a center hole jack, 9 is a steel rod, 10 is a pressure girder, 11 is a center hole jack, 13 is a steel bar, 14 is a pressure girder, 1
5 is the center hole jack, 17 is the supporting layer ground,
19 is a female threaded insert, 20 is a vertical reinforcing bar, 2
1 is the horizontal reinforcement, and 22 is the foundation concrete.

Claims (1)

[Claims] 1 A step in which a pile caisson 2 is installed in the main body caisson 1 so as to be able to be raised and lowered, and the pile caisson 2 is press-fitted into the ground using the main body caisson 1 as a reaction force support. A caisson sinking method that is characterized by alternating the process of press-fitting into the ground.