JP2000129699A - Earthquake resisting underground structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underground structure wherein the frictional force between the underground structure and soil mounted thereon at the time of an earthquake can be reduced and direct soil pressure can be prevented from increasing, and hence increase in cost can be limited, without increasing the strength of the structure as compared with a conventional one. SOLUTION: The earthquake resistant underground structure consists of an underground structure body 1, buried in the ground, a slide part 5 which is composed of low friction materials and laid on an upper slab 1a of the body 1, and a soft material 6 which is softer than the surrounding ground 3 and disposed on the sides of the body 1. In this case, the frictional force between the part 5 and the body 1 is made smaller than the frictional force between soil 2 mounted directly on the body 1 and the body 1, which prevents direct soil pressure from increasing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an earthquake-resistant underground structure.

[0002]

2. Description of the Related Art Conventionally, open-cut tunnels have been constructed in holes dug in the ground. FIG. 2 shows a conventional example in which a rectangular underground structure main body 1 is constructed in a hole H dug in the ground. In FIG. 2, the upper slab 1a of the underground structure main body 1
Is covered with no soil or sand 2 for keeping the underground structure main body 1 in a buried state. These soil and sand 2
Since it is mounted on the upper slab 1a of the underground structure main body 1, it is hereinafter referred to as "overlaying soil 2".
The soil or sand in the hole H corresponding to the outer wall surface other than a is referred to as “peripheral buried soil 3” for convenience. 2 and FIG.
Is a space in the underground structure main body 1,
Cars and trains can pass through them.

[0003] Since the underground structure main body 1 has a rectangular shape, the slab 1a has a planar shape. When the underground structure main body 1 having the upper slab 1a having such a planar shape is constructed in the hole H and then buried with the overlying earth 2, the overlying earth 2 becomes
It is received by the upper slab 1a. And since the underground structure main body 1 is usually buried deep underground, the upper slab 1a
The weight of the overlying soil 2 hanging on is very heavy. For this reason, the underground structure main body 1 is pressed downward by the upper soil 2 via the upper slab 1a. That is, the weight of the upper soil 2 directly acts on the upper slab 1a of the underground structure main body 1 as the earth pressure.

On the other hand, since the underground structure main body 1 is made of concrete, it generally has higher rigidity than the overlying soil 2 and the surrounding buried soil 3 around the underground structure main body 1. Therefore, when the ground including the underground structure main body 1 rolls as shown by an arrow 4 in FIG. 2 due to, for example, an earthquake, the overburden 2 is moved by the inertial force at that time as shown in FIG. A relative displacement occurs with respect to the object body 1.

[0005] When such a displacement occurs, the upper ground 2
The weight of the upper slab 1a does not act on the upper slab 1a as mere earth pressure, but rather acts on the upper slab 1a in the direction opposite to the arrow 4
a) as a force for horizontally pulling a. For this reason, a large frictional force is generated between the upper soil 2 and the upper slab 1a. This frictional force may cause large shear deformation in the underground structure main body 1.

Therefore, conventionally, the strength of the underground structure main body 1 is increased by increasing the number of reinforcing bars used for the underground structure main body 1 or by increasing the amount of concrete to be used. The object body 1 has been prevented from being damaged during an earthquake.

[0007]

However, in the conventional underground structure body 1, it is necessary to increase the strength by increasing the number of reinforcing bars and the amount of concrete used as described above, so that the cost is increased. There was a problem of becoming.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a conventional problem, and it is possible to prevent a large frictional force from being transmitted to an underground structure body during an earthquake and to act on the underground structure. The direct earth pressure can be prevented from excessively increasing,
Accordingly, it is an object of the present invention to provide an underground structure which does not need to increase the strength as compared with the related art and suppresses an increase in cost as compared with the related art.

[0009]

SUMMARY OF THE INVENTION The present invention relates to an earthquake-resistant underground structure, and has the following structure to solve the above-mentioned technical problem. That is, the seismic resistant underground structure of the present invention comprises an underground structure body in a buried state, a sliding portion made of a low friction material laid on an upper slab of the underground structure body, and a surrounding ground. A soft material that is soft and disposed on the side surface of the underground structure main body, and the frictional force between the sliding portion and the underground structure main body directly applies the overburden to the underground structure main body. It is characterized in that it is smaller than a frictional force generated between the overlying soil and the underground structure main body when it is placed.

[0010] This earthquake-resistant underground structure can reduce the frictional force generated between the upper slab and the upper soil during an earthquake. Further, the direct earth pressure acting on the underground structure main body from the surrounding ground is absorbed by the soft material and reduced.

[0011] The soft material may be disposed on an upper side of the side surface of the underground structure main body. In this case, since the dispersive force of the ground stress concentrated on the end of the sliding portion is absorbed by the soft material, it is possible to prevent an increase in the direct earth pressure acting on the side surface of the underground structure.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an earthquake-resistant underground structure according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an earthquake-resistant underground structure A according to the present invention.
1 is shown. The earthquake-resistant underground structure A1 is disposed on the underground structure main body 1, a sliding portion 5 made of a low-friction material disposed on the upper surface of the upper slab 1a, and a side surface of the underground structure main body 1. The underground structure body 1 is made up of a soft material 6
Is embedded together with the sliding portion 5 and the soft material 6. Sliding part 5
Are laid with substantially the same width as the upper slab 1a.

The low-friction material referred to here means that the frictional force generated between the low-friction material and the underground structure main body 1 is such that the upper soil 2 is directly placed on the underground structure main body 1. It is formed of a material that is smaller than a frictional force generated between the upper soil 2 and the underground structure main body 1. Further, the soft material 6 is softer than the surrounding buried soil 3 and is softer than the surrounding buried soil 3.
For example, a material that absorbs the direct earth pressure Q acting on the underground structure main body 1 such as rubber can be used. In the present embodiment, it is effective to arrange the soft material 6 on the upper side of the side surface of the underground structure main body 1, but it is not particularly limited to the upper side, and the soft material 6 may be continuous from the upper side to the lower side. Good.

The difference between the earthquake-resistant underground structure A1 of this embodiment and the above-mentioned prior art (FIGS. 2 and 3) is that the sliding portion 5 is placed on the upper surface of the upper slab 1a of the underground structure main body 1. The point is that the underground structure main body 1 is buried in this state, and the soft material 6 is arranged on the side surface of the underground structure main body 1. Other configurations are the same as those of the conventional underground structure 1 shown in FIG. 2, and therefore, the same portions are denoted by the same reference characters and will not be described in detail.

When the underground structure main body 1 in the buried state is displaced from the upper soil 2 by vibration such as an earthquake, the sliding portion 5 is covered with the sliding portion 5. The frictional force generated between the upper slab 1a and the slab 1a
a, the upper slab 1a
The coefficient of friction between the upper slab 1a, that is, the material and the state of the sliding portion 5 are set so that the frictional force generated between the upper slab 1 and the upper slab 1a is smaller than the frictional force generated between the two when the upper soil 2 is directly covered. I just need. The sliding portion 5 and the soft material 6
Must be present in the ground for long periods of time, so that it can withstand heat, cold, moisture and other external factors.

When such an earthquake-resistant underground structure A1 is buried in the ground, the frictional force generated between the sliding portion 5 and the underground structure main body 1 is higher than that of the underground structure main body 1 and the overlying soil. 2 becomes smaller than the frictional force generated between them.

As a result, for example, the seismic resistant underground structure A1 is shaken enough to cause a lateral displacement due to the occurrence of an earthquake, and the underground structure main body 1 is moved by the influence of inertia at that time. Even if a displacement occurs with respect to the upper soil 2 or the surrounding buried soil 3, the frictional force generated between the upper slab 1a and the sliding portion 5 is reduced, so that the strength of the underground structure main body 1 is increased as compared with the conventional case. That is, the underground structure body 1
The underground structure body 1 can be prevented from being damaged at the time of an earthquake without increasing the amount of reinforcing steel or concrete used in the conventional method.

By setting the thickness of the soft material 6 as appropriate, the direct earth pressure Q acting on the underground structure main body 1 from the surrounding buried soil 3 can be absorbed by the soft material 6. In particular, the ground stress concentrates on the end 5a of the sliding portion 5, and the concentrated ground stress is absorbed by the soft material 6, so that the increase in the direct earth pressure Q can be prevented.

As described above, in the earthquake-resistant underground structure according to the present invention, the underground structure main body 1 is moved from the overlying soil 2 during an earthquake.
And the direct earth pressure Q acting on the underground structure body 1 from the surrounding buried soil 3 can be prevented from increasing, so that the number of reinforcing bars of the underground structure body 1 and the concrete Since the strength of the underground structure main body 1 can be substantially increased without increasing the used amount as compared with the conventional case, the cost can be reduced.

[0021]

As described above, according to the earthquake-resistant underground structure of the present invention, the frictional force between the underground structure generated during an earthquake and the overlying soil can be reduced, and at the end of the sliding portion. By absorbing the concentration of generated ground stress with soft material,
Since it is possible to prevent the direct earth pressure acting on the underground structure from increasing from the surrounding ground, it is not necessary to increase the number of reinforcing bars used by the underground structure and the amount of concrete used as before, and to increase the strength, Cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an earthquake-resistant underground structure according to the present invention.

FIG. 2 is a sectional view showing an underground structure according to a conventional example.

FIG. 3 is a cross-sectional view showing an operation of an underground structure according to a conventional example during an earthquake.

[Explanation of symbols]

 A1 Earthquake-resistant underground structure 1 Underground structure body 1a Upper slab 2 Overlay 5 Sliding part 6 Soft material

Claims (2)

[Claims] 1. An underground structure main body in a buried state, a sliding portion made of a low friction material laid on an upper slab of the underground structure main body, and the underground structure main body softer than a surrounding ground And a soft material disposed on the side surface of the underground structure body, the frictional force between the sliding portion and the underground structure body, when the overlying soil is directly placed on the underground structure body, An earthquake-resistant underground structure having a frictional force smaller than a friction force generated between the underground structure body and the underground structure body. 2. The earthquake-resistant underground structure according to claim 1, wherein the soft material is arranged on an upper side of a side surface of the underground structure main body.