JPH0565657B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a caisson sinking method in which a cylindrical caisson is installed by sinking it into the ground.

[Problem that the invention seeks to solve]

Conventionally, in the method of lowering a cylindrical caisson into the ground and installing it at a target depth, the ground is excavated to the interior of the caisson, including the walls.

When using a caisson as a foundation structure, after the caisson is sunk, the hollow part of the excavated caisson is filled with concrete or backfilled with earth and sand to anchor it to the ground. In terms of strength, the walls of the caisson are often sufficient, so it is extremely wasteful work to excavate the inner part of the caisson and construct a concrete bottom slab there after the caisson is sunk, or to backfill with earth and sand. In particular, the labor and time required to excavate and backfill the hollow part of the caisson, which has a huge volume, is large, resulting in a loss of construction time and construction costs.

In addition, in order to sink the caisson while maintaining its verticality, careful consideration is required to prevent soil pressure and friction during excavation, and the caisson usually slopes to a certain extent when it sinks. Therefore, we need a device to correct this. Consideration for earth pressure and inclination at the time of submersion extends to the interior of the caisson.
In other words, since this is a countermeasure that involves excavating the entire cross section of the caisson, the problem of inclination can be avoided to some extent by omitting excavation of the inner cavity of the caisson.

This invention was made based on the actual situation of conventional undergrounding methods, and aims to propose a method that can reduce the amount of effort and time required for excavation work, and at the same time allows for vertical undergrounding.

[Means for solving problems]

In the present invention, a plurality of long grooves are formed in the wall of a cylindrical caisson in the axial direction and bored along the wall surface in the wall so as to be symmetrical with respect to the central axis of the caisson. An excavator is placed over the opening of the long groove symmetrically with respect to the central axis, and while moving along each opening while maintaining a symmetrical state, the blade of the excavating shaft of the excavator inserted into the long groove is inserted into the inside and outside walls of the caisson. Excavation is performed by rotating between the cutting edges attached to the lower edge, and the excavated soil is discharged upward from the earth removal pipe installed in the excavation shaft, greatly reducing the amount of excavated soil and at the same time excavating the inner space. This eliminates the need for backfilling the construction of concrete slabs, thereby shortening the construction period and reducing construction costs.

In addition, by installing a jet nozzle on the excavator and injecting water at the same time as excavation, the frictional force acting on the inner and outer surfaces of the wall is reduced, making it easier to maintain the verticality of the caisson and preventing the caisson from sinking. Do it smoothly.

〔Example〕

The present invention will be explained below based on the drawings showing one embodiment.

In this invention, a plurality of long grooves 2 are formed axially through a wall 1 of a cylindrical caisson A and bored along the wall surface in the wall 1 so as to be point symmetrical with respect to the central axis of the caisson A. The blade body (bit 4) of the excavation shaft inserted into the long groove 2 while moving along each opening of the excavator B, which is placed symmetrically with respect to the central axis above the opening of the long groove 2 above the caisson, is inserted into the caisson. Inside A
Excavation is carried out by rotating between the cutting holes 3 and 3 attached to the lower edge of the outer wall, and the excavated soil a is discharged upward from the earth removal pipe 5 provided in the excavation shaft, and this excavator B is used to excavate the wall of the caisson A. This is a method in which the caisson A is lowered and installed on the target ground each time the ground at the lower end is excavated.

As shown in Figures 2 and 3, the caisson A has a circular or rectangular cross section, and the long groove 2 is connected to the wall 1.
A plurality of slits are axially penetrated into the inside of the slit, and are continuously opened in a certain section along the circumferential direction. The long grooves 2 are formed in an even number because at least two excavators B and B are arranged symmetrically with respect to the center of the caisson A, as will be described later.

The excavator B rotates its excavation shaft using a rotary table installed at the upper end of the wall 1. The excavation shaft is inserted into the long groove 2, and the blade attached to its lower end, that is, the bit 4, rotates between the cutting edges 3 and 3 attached to the lower edges of the inner and outer walls of the wall 1 of the caisson A. Excavate the ground at the bottom of the The excavated soil a is transferred from bit 4 to rotary table 7.
The earth is discharged to the ground by the earth discharge pipe 5 which is laid down to the earth. From the rotary table 7 to the bit 4, an air supply pipe 6 for sending compressed air b to catch the excavation of the bit 4 is also laid in parallel to the earth removal pipe 5.

As shown in Fig. 1, the blade openings 3 are provided so as to protrude from the outer and inner circumferential sides of the wall 1, facing each other, and prevent the earth and sand on both sides of the wall 1 from flowing into the bit 4 side during excavation. are doing.

Next, the construction procedure will be explained.

For the purpose of preventing the inclination and eccentricity of caisson A, excavator B is
At least two units will be installed symmetrically with respect to the center of the area. The rotary table 7 is placed on a moving frame 8 placed on the upper end of the caisson A, and moves at least two excavators B while maintaining the symmetrical shape. At the same time as this movement, excavation by bit 4 is performed. Install excavator B in full-length trench 2,
When the ground at the tip of the wall 1 is excavated evenly and at the same time, the efficiency of excavation and vertical maintenance are further improved.

The cutting shafts of the excavators B and B, which move along the long groove 2 on the movable frame 8, are rotated by the rotary table 7 to rotate the bit 4, while compressed air b is sent from the air pipe 6 to remove the excavated soil a. This is done while discharging the soil through the soil discharging pipe 5. At this time, as shown in FIG.
By installing water c and spraying water c from the bit 4, it is possible to suppress the friction acting on the outer circumferential surface and the inner circumferential surface of the wall body 1 of the caisson A, and to suppress the inclination of the caisson A. The injection of water c assists excavation, and also plays a role in assisting excavation of difficult-to-excavate areas between adjacent long grooves 2, 2.

As mentioned above, the excavators B and B, which are arranged symmetrically about the center axis of the caisson A, are connected to the slit-shaped long grooves 2 and 2.
By moving the caisson along the caisson A, the caisson A is moved downward while keeping the excavated ground level horizontally, that is, while maintaining the verticality of the caisson, and causes the caisson A to sink vertically.

After completing the sinking work of caisson A, the long groove 2 is filled with concrete or grout to complete the entire sinking work.

〔Effect of the invention〕

The present invention is as described above, and a plurality of openings into which an excavator is inserted are bored through the wall body in the axial direction, and excavation is performed only in the wall body portion of the caisson. Since excavation is omitted,
The amount of excavated soil is significantly reduced, and at the same time, backfilling work is no longer necessary, shortening the construction period and reducing construction costs. In addition, since excavation is done only on the wall, the risk of heaving and poiling is reduced, the ground is not disturbed, and dangerous work and incomplete excavation are eliminated.

In particular, since each opening is continuously opened in a certain area in the circumferential direction of the wall, even when changing the excavation position, the relocation work of pulling out and inserting the excavator is omitted, greatly increasing the efficiency of excavation. This can improve the efficiency of caisson laying work.

In addition, since the excavator is placed symmetrically with respect to the center of the cross section of the wall and moves along the opening while maintaining a symmetrical state in the circumferential direction, uneven earth pressure on the wall during construction is reduced, and the wall The wall can be made into an economical cross-section, and at the same time, the inclination and eccentricity of the caisson can be prevented, the verticality of the caisson can be maintained, and the entire circumference of the wall can be sunken evenly.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an excavation situation according to the present invention. FIGS. 2 and 3 are plan views illustrating the cylindrical caisson of the present invention. FIG. 4 is an enlarged sectional view of the bit portion when a jet nozzle is attached to the bit. A...caisson, B...excavator, 1...wall,
2...long groove, 3...blade mouth, 4...bit, 5...
Earth removal pipe, 6...Transfer pipe, 7...Rotary table, 8...Movement stand, 9...Water pipe, 10...
Jet nozzle, a... excavated soil, b... compressed air, c... water.

Claims (1)

[Claims] 1 A plurality of long grooves are formed in the wall of a cylindrical caisson in the axial direction and bored along the wall surface in the wall so as to be symmetrical with respect to the central axis of the caisson, and the long grooves above the caisson are An excavator is placed above the opening symmetrically with respect to the central axis, and is moved along each opening while maintaining a symmetrical state, and the blade of the excavator shaft inserted into the long groove is inserted into the lower edge of the inner and outer walls of the caisson. Rotate between the blades attached to the blade to complete the excavation.
A caisson sinking method characterized by discharging excavated soil upwards through a discharge pipe installed within the excavation shaft.