JP2809105B2 - How to build an underground tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for constructing an underground tank.

[0002]

2. Description of the Related Art An underground tank used for storing LNG, crude oil, and the like is generally constructed by the following procedure.

(1) Select an impermeable layer such as clayey soil at an appropriate depth in the ground.

(2) A water blocking wall (such as an underground continuous wall) reaching a water-impermeable layer is constructed in a cylindrical shape.

(3) Excavate the ground inside in a dry state while draining groundwater inside the water stop wall.

(4) A skeleton (bottom plate and side walls) is constructed on the excavated ground.

[0007]

In the conventional construction method, it is necessary to first shut off the construction site with a water stop wall to block the inflow of groundwater. For this reason, (1) it is difficult to construct in a place where there is no impermeable layer at an appropriate depth. (2) Further, when the construction is performed using a water-impermeable layer at a deep position, a large construction cost is required for constructing the water blocking wall, and the overall construction cost is increased. There is a disadvantage that.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned drawbacks, the present invention provides a construction method for directly constructing an underground tank in a state where the construction of a water stop wall is omitted and the inflow of groundwater is allowed. The purpose is to rationalize tank construction.

That is, the present invention provides (A) a step of constructing a side wall provided with a digging means and an earth discharging means at a lower end on a ground portion;
(B) sinking the side wall while excavating the ground below the side wall,
(C) building a slab inside the side wall and excavating the ground inside the side wall,
(D) A method of constructing an underground tank, comprising the steps of laying a floor slab and constructing a joint with a side wall.

The most important point of the present invention is that the construction of the water blocking wall is omitted.

Therefore, it is necessary to first construct the side wall under the ground. The construction of this side wall is performed as follows.
(1) The first side wall, which is obtained by dividing the entire side wall into about 5 to 10 steps in the height direction according to the height of the underground tank, is constructed on the ground. (2) Excavate the ground immediately below the first stage side wall and sink it by the height of the side wall. (3) Reinforced concrete is constructed just above the first-stage side wall, and the second-stage side wall is constructed on the ground. (4) Excavate the ground immediately below the first stage side wall and sink it by the height of the second stage side wall. (5) Thereafter, the construction and sinking of the upper side wall on the ground portion are repeated, so that the side wall having a predetermined height is built at a predetermined position. When the side wall is constructed, a suitable number of guide rails for guiding a slab to be constructed later are attached to the inner surface thereof in the vertical direction.

In order to excavate the ground immediately below the side wall, it is necessary to provide an excavating means and an earth discharging means at the lower end of the side wall of the first stage. A typical example of this excavating means is in the vertical direction of the side wall. A water jet pipe communicating therewith is mentioned, and a typical example of the earth discharging means is a mud pipe communicating vertically in the side wall. A predetermined number of these pipes are buried along the circumferential direction when the side wall is constructed, and are connected at the time of splicing, and open to the lower end of the side wall and the ground. Therefore, excavation by injection of high-pressure water and earth removal by suction of mud slurry can be easily performed by operation from the ground portion.

In addition, the following are also used as the excavating means and the earth discharging means.

A shovel is hung on a guide rail provided at a lower end of the side wall in a circumferential direction, and excavation is performed by the shovel and the excavated soil is moved to an excavated portion. Unloading from the unloading section is performed by a vertical conveyor provided in the side wall or a large bucket.

The side wall is usually laid down by sinking into the excavation groove by its own weight, but if necessary, it is press-fitted together with an earth anchor or the like.

When the side wall having a predetermined height is formed at a predetermined position, the process proceeds to the construction of a floor slab.

The construction and subsidence of floor slabs are roughly classified into the following three systems.

First method: (1) The inside of the side wall is excavated underwater to the floor slab mounting position by an operation from the ground portion, and the floor slab mounting surface is shaped.

(2) After constructing a slab having a hollow structure on water, water is poured into the hollow portion and settled at a predetermined position along the guide rail on the side wall.

Second method: (1) The upper part inside the side wall is excavated to a depth necessary for building a slab, and a slab having a hollow structure having a working through hole is constructed thereabove by ground work.

(2) Using the floor slab as a work table, excavating under the floor slab to the floor slab mounting position underwater to shape the floor slab mounting surface.

(3) Water is poured into the hollow portion of the floor slab floating on the water, and settled at a predetermined position along the guide rail on the side wall.

Third method: (1) Excavate the upper part of the inside of the side wall to the depth required for building the slab, and construct a slab having a working through hole by ground work using the side wall as a support. (The floor slab may have either a hollow structure or a solid structure.) (2) Using the floor slab as a working table, excavate underwater to the floor slab mounting position under the floor slab to shape the floor slab mounting surface.

(3) The support by the side wall of the floor slab is released, and the floor slab is sunk at a predetermined position along the guide rail of the side wall.
(If the floor slab has a hollow structure, water is injected into the hollow part.) Which of the first to third methods is used depends on the condition of the ground, the height of the groundwater level, the shape, size, and construction of the underground tank. It is determined by taking into account the difficulty and construction period.

In either case, after the floor slab is laid, the joint between the floor slab and the side wall is constructed by the operation from the ground, and the hollow part of the floor slab is filled with underwater concrete and the frame of the underground tank is constructed. Is completed, and the internal groundwater is drained.

In the case where the lower part of the side wall sunk according to the present invention reaches the water-impermeable layer and the side wall becomes a water-blocking wall, the construction of the floor slab is not performed by the above-mentioned respective methods, but by the conventional inside of the side wall. It is preferable to adopt a construction method of digging the inner ground in a dry state while pumping groundwater to construct a slab and a joint between the slab and the side wall.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing one example of the first stage of the side wall of the underground tank constructed according to the present invention.

A pair of water jet pipes 2 and 2 are vertically buried near the inner and outer surfaces of the side wall 1 constructed on the ground, and the ends thereof are provided on the legs of the side wall 1 toward the center of the side wall 1. Connected to the injection ports 4, 4 provided. A mud pipe 3 is buried in the center of the side wall 1 in the vertical direction, and its end is opened at the center of the lower end of the side wall 1. A plurality of pairs of water jet pipes 2 and 2 and a plurality of mud pipes 3 are buried at appropriate intervals along the circumference of the side wall 1.

When submerging the side wall 1, high-pressure water sent from the water jet pipes 2 and 2 is injected into the injection ports 4 and 4.
Excavation is performed to excavate the ground immediately below the side wall 1, and the resulting mud slurry is pumped up through the mud pipe 3 to advance excavation. The side wall 1 sinks into the excavated trench by its own weight or its own weight plus press-fitting. Naturally, the excavation is carried out in a balanced manner over the entire circumference of the side wall 1 and care is taken that the side wall 1 sinks without tilting.

When the first-stage side wall 1 is laid down, the second-stage side wall 1 is constructed on the laid-down first-stage side wall 1. 3 is extended upward by connection, and the extended portion is the second side wall 1
Buried in In this manner, the water jet pipes 2 and 2 and the mud pipe 3 are extended upward as the side wall 1 is laid down and constructed.

FIGS. 2A and 2B are process vertical sectional views showing the subsidence of the side wall of the underground tank constructed in the present invention. FIG. 2A shows the initial stage of subsidence, FIG. 2B shows the middle stage of subsidence, and FIG. Show.

Excavation is performed immediately below the side wall 1 constructed on the ground, and the subsidence of the side wall 1 is started (see (a)). The deposition of the side wall 1 and the construction of the side wall 1 thereon are repeated several times (see (b)). The side wall 1 is constructed to a predetermined height, and the subsidence of the side wall 1 is completed (see (c)).

FIG. 3 to FIG.
FIG. 3 is a process vertical sectional view showing an example of a procedure for constructing and laying a floor slab. FIG. 3 corresponds to the first method, FIG. 4 corresponds to the second method, and FIG. This corresponds to three systems.

The procedure of FIG. 3 will be described.

(1) The inside of the side wall 1 is excavated underwater to the floor slab mounting position by an operation from the ground portion to shape the floor slab mounting surface. (See (a)) (2) The floor slab 5 having a hollow structure is constructed on water. (See (b)) (3) Water is poured into the hollow portion of the floor slab 5 and settled at a predetermined position along a guide rail (not shown) of the side wall 1. ((C)
(Refer to FIG. 4).

(1) The upper part inside the side wall 1 is excavated to a depth required for building a floor slab, and a floor slab 5 having a hollow structure having a working through hole is constructed thereabove by ground work. (See (a).) (2) Using the floor slab 5 floating on the water as a working table, the ground below the floor slab 5 is excavated underwater to the floor slab mounting position, and the floor slab mounting surface is shaped. (See (b)) (3) Water is poured into the hollow portion of the floor slab 5 and settled at a predetermined position along a guide rail (not shown) of the side wall 1. ((C)
(Refer to FIG. 5).

(1) Excavating the upper part of the inside of the side wall 1 to a depth necessary for building the floor slab, and constructing a solid structure floor slab 6 having a working through hole by ground work using the side wall 1 as a supporting material. .
(See (a)) (2) Under the floor slab 6, using the floor slab 6 as a work table, the ground below the floor slab 6 is excavated underwater to the floor slab mounting position to shape the floor slab mounting surface.
(3) The support of the floor slab 6 by the side wall 1 is released and the floor slab 6 is sunk at a predetermined position along a guide rail (not shown) of the side wall. (See (c))

[0039]

【The invention's effect】

(1) Since the construction of the water stop wall which accounts for about half of the construction cost can be omitted, the construction cost of the underground tank can be significantly reduced.

(2) Since an underground tank can be constructed even in a place where an impermeable layer does not exist at an appropriate position, the degree of freedom in selecting an underground tank construction place is greatly expanded.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a side wall of an underground tank constructed according to the present invention.

[Fig. 2] Fig. 2 shows the subsidence of the underground tank constructed by the present invention
It is a process longitudinal cross-sectional view which shows an example, (a) is an initial stage of siding,
(B) shows the middle stage of subsidence, and (c) shows the end of subsidence.

FIG. 3 is a process vertical sectional view showing an example of construction / deposition of a floor slab of an underground tank constructed according to the present invention.

FIG. 4 is a process vertical sectional view showing another example of construction and subsidence of a floor slab of an underground tank constructed according to the present invention.

FIG. 5 is a process vertical sectional view showing another example of construction and subsidence of a floor slab of an underground tank constructed according to the present invention.

[Explanation of symbols]

1 .... side wall, 2 .... water jet pipe, 3 .... mud pipe, 4 .... injection port, 5 .... hollow structure floor slab, 6 .... solid structure floor slab.

Claims (2)

(57) [Claims] (A) a step of constructing a side wall provided with a digging means and an earth discharging means at a lower end on the ground part; and (B) digging the ground below the side wall while sunk the side wall to place the side wall at a predetermined position. (C) a step of constructing a slab inside the side wall and excavating the ground inside the side wall, and (D) a step of laying down the slab and constructing a joint with the side wall. How to build 2. The method for constructing an underground tank according to claim 1, wherein the excavating means at the lower end of the side wall is a water jet pipe, and the discharging means is a mud pipe.