JPH05287768A - Joining construction of underground structure having buoyancy - Google Patents

Abstract

PURPOSE:To join a continuous underground wall with a skeleton side wall so that only a short portion of weight of a skeleton against buoyancy uses weight of the continuous underground wall to make it possible to realize the reduction of costs in the case the continuous underground wall, is contacted with the skeleton side wall to form and to join them so that an amount of excavation is reduced and that it is not necessary to increase the thickness of a side wall or a bottom slab, even if the ground is settled, and to make it possible to minimize any interference of the side wall or the continuous underground wall so that the side wall can be slid freely in the direction of a radius. CONSTITUTION:In an underground structure having a skeleton equipped with a bottom slab formed by contacting with the bottom of a hole bored in the ground and a side wall rising upward from the peripheral surface of the bottom slab, the side wall 6 is formed by approaching to a continuous underground wall 1. Anchor steel bars 3 and 9 are projected from the side wall 6 side and the continuous underground wall 1 side to butt at each other, and thick steel pipes 15 are fitted to the peripheral surface of the butted part to couple the anchor steel bars 3 and 9 with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint structure for an underground structure such as an underground tank which receives buoyancy.

[0002]

2. Description of the Related Art The member size of underground structures such as underground tanks on which buoyancy acts is determined from the viewpoint of safety against buoyancy and safety from the viewpoint of strength, but with the increase in size and depth of structures. Therefore, the dimensions of members have come to be determined from the viewpoint of safety against buoyancy rather than strength.

Taking an LNG underground tank as an example, an underground tank has been developed in which the ground is excavated to form a hole, and a part or all of the hole is buried. As shown in FIG. The continuous underground wall c was constructed so as to surround the side wall a and the bottom slab a little apart from the side wall a. The continuous underground wall c is earth retaining,
It is for stopping water, and its lower end reaches the impermeable layer.

As another conventional example, as shown in FIG. 9, there is also one in which a continuous underground wall c and a side wall a are formed in contact with each other and a connecting reinforcing bar d is interposed between them.

[0005]

In the underground tank shown in FIG. 8, since the buoyancy of ground water is received by the side wall and the bottom slab, it must have a certain weight. Therefore, the member thickness of the side wall a and the bottom slab b is determined not by the degree of stress (strength) but by the stability with respect to the buoyancy, so that the member thickness becomes large. Further, since there is a gap between the side wall a and the continuous underground wall c, the amount of excavated soil increases, and an outer formwork for the side wall is also required. Furthermore, since the side wall a and the continuous underground wall c are separated, the circumferential length of the continuous underground wall c becomes long.

In the underground tank shown in FIG. 9, since the side wall a and the continuous underground wall c are connected by the connecting rebar d for transmitting the shearing force, the weight of this continuous underground wall c resists the buoyancy of the underground tank. It can be seen as force, and it is not necessary to increase the thickness of the side wall a and the bottom slab b. In addition, continuous underground wall c
Since the side wall a and the side wall a are formed in contact with each other, the amount of excavation is small, a formwork outside the side wall is not necessary, and the circumference of the continuous underground wall c is small.

However, since the side wall a and the continuous underground wall c are connected by the reinforcing bar d to form an integral joint, the side wall a is restrained by the continuous underground wall c, and the LNG underground tank is resistant to deformation due to cold heat. I can not cope.

The object of the present invention is to eliminate the disadvantages of the conventional example, to form a continuous underground wall and a side wall of a structure close to each other so that the amount of excavation is small and the thickness of the side wall and bottom slab is not required to be large. In addition, when the side wall and the continuous underground wall are coupled so as to transmit a shearing force, the side wall can be freely slid in the (tank) radial direction and either the side wall or the continuous underground wall can be arranged. It is to provide a joint structure for an underground structure that receives buoyancy that can minimize interference with.

[0009]

In order to achieve the above-mentioned object, the present invention provides a skeleton having a bottom slab formed by abutting on the bottom surface of a hole excavated in the ground, and a side wall rising upward from the outer periphery of the bottom slab. In an underground structure having, the side wall is formed in the vicinity of the continuous underground wall, and steel rods for anchoring are projected and abutted from the side wall side and the continuous underground wall side, and the steel pipe is provided on the outer periphery of the abutted portion. And connecting the steel rods for anchors with each other, and for the steel rods for anchors, a plurality of the steel rods for anchors are juxtaposed in parallel, and further, the side wall side and the continuous underground wall side are fitted together to form one grout. The gist of the present invention is to embed a box divided body that constitutes a box and to project an anchor steel rod into the box divided body.

[0010]

According to the first aspect of the present invention, since the side wall and the continuous underground wall are connected by connecting the steel rods for anchors to each other, buoyancy received by the bottom plate and the side wall is transmitted to the continuous underground wall. The underground wall also bears the resistance to buoyancy. Therefore, the thickness of the side wall and the bottom slab can be made relatively small, and the construction cost can be reduced.

Further, since the anchor steel rods of the side wall and the continuous underground wall are not restricted by each other in the length direction, the side wall can freely slide in the (tank) radial direction.
It can cope with deformation caused by cold heat. Moreover, if the subsidence of the side wall during construction is slight, it can be absorbed by the clearance between the steel pipe and the anchor steel rod.

According to the second aspect of the present invention, in addition to the above-mentioned action, a plurality of anchor steel rods are provided so as to be juxtaposed in parallel, and by this number, the side wall and the continuous underground wall are surely provided. The shearing force acting between and can be transmitted.

According to the present invention of claim 3, further,
By injecting grout material into the grout box, it is possible to prevent rust at the joints between the anchor steel rods.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. 4 to 7 are partial side views of respective steps showing an example of a construction method of a joint structure of an underground structure subjected to buoyancy according to the present invention.

As shown in FIG. 4, the continuous underground wall 1 is circularly constructed so as to surround the underground tank to be constructed first. This continuous underground wall 1 serves to stop water and retain soil, and the lower end reaches the impermeable layer. Then, as shown in FIGS. 1 and 2, in the continuous underground wall 1, a box division is formed in which the grout box 2, which is a flat vertical steel box, is fitted to each other in the vertical middle portion. One of the bodies 2a and 2b is embedded in the divided body 2a, and a plurality of anchor steel rods 3 are embedded in parallel, and the ends thereof are projected into the box divided body 2a. In this case, anchor steel rod 3
The tip of the box does not protrude from the split open surface of the box split body 2a.

Then, the split open surface of the box split body 2a is covered with a protective steel plate 7 as shown in FIG.
In the figure, 8 is a bolt for fixing the protective steel plate 7 to the box divided body 2a.

As shown in FIG. 5, a hole 4 is formed by excavating the inside of the continuous underground wall 1. After excavation, the protective steel plate 7 is removed. Next, as shown in FIG. 6, concrete is cast on the bottom surface of the hole 4 to form the bottom plate 5 so as to contact the ground. Further, the side wall 6 is raised from the outer periphery of the bottom plate 5. The side wall 6 is formed near the continuous underground wall 1 described above.

A box division body 2b constituting the grout box 2 is embedded also on the outer peripheral surface of the side wall 6, and further, a plurality of anchor steel rods 9 are embedded in parallel, and an end portion thereof is embedded in the box division body. It is made to project in 2b. Also in this case, the tip of the anchor steel rod 9 does not protrude from the split open surface of the box split body 2b.

The box division body 2b is provided with a grout injection hose 13 and an exhaust hose 14, and the box division body 2a is provided.
And the box divided body 2b are combined to form one grout box 2. The ends of the anchor steel rod 9 on the side wall 6 side and the anchor steel rod 3 on the continuous underground wall 1 side abut each other, but a thick steel pipe 15 is fitted to the outer periphery of the abutting portion to anchor steel. The rods 3 and 9 are connected to each other.

The side walls 6 are sequentially raised to construct a skeleton with the bottom slab 5, but the ground subsides due to the weight of this skeleton, and the side walls 6
However, even if it is slightly lowered with respect to the continuous underground wall 1, the deviation between the anchor steel rods 3, 9 and the thick-walled steel pipe 15 can be absorbed.

After the skeleton is completed, the grout material is injected into the grout box 2 through the grout injection hose 13, and the grout box 2 is filled with the grout material. Further, as shown in FIG. 7, a roof 11 is placed on the side wall 6 and an embankment 12 is provided around the roof 11.

As described above, the anchor steel rod 3 protruding from the continuous underground wall 1 and the anchor steel rod 9 protruding from the side wall 6
And are connected by a thick-walled steel pipe 15 to form a support for transmitting a vertical force, and the weight of the continuous underground wall 1 can be used as a resistance against the buoyancy of the body.

Moreover, since the anchor steel rods 3 and 9 are not constrained to each other in the lengthwise direction and the side wall 6 can freely slide in the (tank) radial direction, it is possible to cope with deformation due to cold heat. it can.

Furthermore, since the connecting portions of the anchor steel rods 3 and 9 are grouted around the inside of the grout box 2, rust can be prevented.

[0025]

As described above, the joint structure of the underground structure which receives the buoyancy of the present invention has a small amount of excavation and a continuous underground wall and a side wall of the body so that it is not necessary to increase the thickness of the side wall and the bottom slab. Are formed close to each other and are coupled so as to transmit the shearing force acting between the side wall and the continuous underground wall, so that the buoyancy force received by the bottom slab or side wall is transmitted to the continuous underground wall as well. The walls also bear the resistance to buoyancy, and the thickness of the side walls and the bottom slab can be made relatively small, and the construction cost can be reduced.

Further, the side wall can be freely slid in the radial direction (tank) so that interference with the bar arrangement of the side wall or continuous underground wall can be minimized, and a highly reliable joint can be obtained. It is a thing.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view of an essential part showing an embodiment of a joint structure for an underground structure subjected to buoyancy according to the present invention.

FIG. 2 is a vertical cross-sectional front view showing an embodiment of a joint structure of an underground structure subjected to buoyancy according to the present invention, with a part of a main part omitted.

FIG. 3 is a vertical cross-sectional side view showing a state at the time of construction with a part of a main part omitted.

FIG. 4 is a side view of a first step showing an example of a joint structure for an underground structure subjected to buoyancy according to the present invention.

FIG. 5 is a side view of a second step showing an example of the joint structure of an underground structure subjected to buoyancy according to the present invention.

FIG. 6 is a side view of a third step showing an example of the joint structure for an underground structure subjected to buoyancy according to the present invention.

FIG. 7 is a side view of the fourth step showing an example of the joint structure for an underground structure subjected to buoyancy according to the present invention.

FIG. 8 is a partial vertical sectional side view showing a conventional example.

FIG. 9 is a partial vertical sectional side view showing another conventional example.

[Explanation of symbols]

1 ... Continuous underground wall 2 ... Grout box 2a, 2b ... Divided body 3 ... Steel rod for anchor 4 ... Hole 5 ... Bottom plate 6 ... Side wall 7 ... Protective steel plate 8 ... Bolt 9 ... Steel rod for anchor 11 ... Roof 12 ... Embankment 13… Grout injection hose 14… Exhaust hose 15… Thick wall steel pipe

Claims (3)

[Claims] 1. An underground structure having a bottom slab formed by contacting a bottom surface of a hole excavated in the ground, and a skeleton having a side wall rising upward from an outer periphery of the bottom slab, close to a continuous underground wall. The side wall is formed, and steel rods for anchoring are projected from the side wall side and the continuous underground wall side and are abutted against each other,
A joint structure for underground structures subjected to buoyancy, characterized in that a steel pipe is fitted around the outer periphery of the abutted portion and steel rods for anchors are connected to each other. 2. The joint structure for an underground structure subjected to buoyancy according to claim 1, wherein a plurality of anchor steel rods are provided so as to be juxtaposed in parallel. 3. A box divided body which is combined with each other on the side wall side and the continuous underground wall side to form one grout box is embedded, and the steel rod for anchor is projected in the box divided body. The joint structure for an underground structure subject to buoyancy according to claim 2.