JP2003313890A - Construction method of underground structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction method favorable for the construction of a long underground structure such as an underground road, a channel or a tunnel, or a non-long underground tank while eliminating the waste of material and labor required for the construction of the underground structure by using the improved ground improved by a deep mixing method, as it is as a structural main body. <P>SOLUTION: This construction method comprises a step of improving the ground for constructing the underground structure, into a range of bearing internal and external force working on the underground structure, by a deep mixing method, a step of excavating the improved ground down to the depth position of a slab bottom plate to construct slab concrete, and a step of using the slab concrete as a strut after the slab concrete manifests required strength, to excavate the improved ground below by a space portion equivalent to the underground structure and finishing the internal wall, floor, and the like of this space to complete the underground structure. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of a construction method for constructing a so-called long underground structure such as a road, a waterway, a tunnel or a non-long underground tank underground, and more specifically, a deep mixing method. The present invention relates to a construction method for an underground structure that uses mainly the improved ground improved by the treatment method.

[0002]

2. Description of the Related Art Conventionally, in the case of constructing an underground structure such as a box culvert used for a tunnel, as shown in FIG. 5, a mountain retaining b is first constructed, and a girder c is temporarily installed together with excavation of the ground. The excavation work is generally carried out by constructing the underground structure a on the excavation bottom part d after completion of the excavation.

As a special example, there is also practiced a reverse construction method in which a basement floor is constructed in advance and used as a girder to excavate the ground.

When it is necessary to take countermeasures against liquefaction and subsidence of the ground, countermeasures against groundwater, etc., the ground is broadly improved in advance, and then the improved ground is subjected to necessary excavation in the underground part of the structure. The open-cut construction method (Japanese Patent Laid-Open No. 6-73722) for promoting the construction of structures has also been implemented.

[0005]

However, the above-mentioned mountain retaining beam construction method requires a large number of temporary members such as mountain retaining b and beam c, and the underground structure a is constructed independently, so that the cost is low. It is bulky and takes a long time to construct.

Although the above-mentioned reverse construction method has an advantage that the use of temporary members can be reduced, it is carried out mainly for the purpose of constructing a building having a living space.
It is not suitable for the construction of so-called long underground structures such as tunnels.

Further, although the above open cut method also has an advantage that the use of temporary members can be reduced, the improved ground is only used as a mountain retaining or a water blocking wall, and the structure is independently constructed on the improved ground. Therefore, there is a lot of waste.

[0008] The object of the present invention is to use the improved ground improved by the deep-mixing processing method as a structural main body so that the waste of materials and labor required for constructing an underground structure can be saved and the cost can be reduced. An object of the present invention is to provide a construction method suitable for constructing so-called long underground structures such as roads, waterways, and tunnels, or non-long underground tanks.

[0009]

[Means for Solving the Problems] As a means for solving the above-mentioned problems, the construction method for an underground structure according to the invention described in claim 1 is a method for constructing a ground for constructing an underground structure into the same underground structure. The step of improving the ground by the deep-mixing method to the extent that the working internal and external forces can be borne, the step of excavating the improved ground to the depth of the slab bottom to construct the slab concrete, and the slab concrete exhibiting the required strength. After that, using this as a truss, the improved ground below is excavated by the space equivalent to the underground structure, and the inner wall of the space,
The stage of finishing the underground structure by finishing the floor etc.,
It is characterized by consisting of.

The invention described in claim 2 is the method for constructing an underground structure according to claim 1, which is prior to the step of excavating the improved ground improved by the deep mixing method to the depth position of the slab floor. Then, a column core material such as H steel is erected at an appropriate portion for supporting the slab concrete, and then the slab concrete is constructed and supported by the column core material, and then the excavation of the improved ground below the slab concrete is performed. It is characterized by advancing and finishing the inner wall and floor of the excavated space.

[0011]

Embodiments and Examples of the Invention FIG. 1 shows an embodiment of a method for constructing an underground structure according to the invention described in claim 1. This construction method is suitably carried out when constructing a so-called long underground structure such as a tunnel, an underground road, a waterway, or a non-long underground tank that is long in the direction perpendicular to the plane of FIG.

As shown in FIG. 1A, the construction method is as follows. First, as shown in FIG. 1A, the ground 1 for constructing the underground structure A is subjected to internal and external forces (earth pressure, groundwater pressure, vertical load, etc.) acting on the underground structure A. ) To the extent that it can bear (range in the horizontal direction and the depth direction) by the deep layer mixing method.

The deep layer mixing processing method here is already known,
Since this is a well-known technique, a detailed illustration and description thereof will be omitted, but in short, a hardening material (stabilizer) is made into a slurry in a plant, and this is pumped to a processing machine by a slurry pump, and the above-mentioned improvement range Using a processing machine, stir and mix excavated soil and hardener slurry uniformly over the entire soft ground of
This is a method for improving the soil to a large depth so that the soft soil can have a predetermined strength. However, the content is not limited to the above.

In other words, the range of ground improvement that can bear the above-mentioned internal and external forces is the range that is mechanically established as an underground structure. For example, the plane area has a wall thickness H required to bear internal and external forces at least on the outer circumference of the underground structure A to be constructed.
It is the area where is added. The depth region is at least the depth of the underground structure A to be built, plus the bottom thickness D required to support the underground structure A.

When the ground improvement is carried out to a predetermined range by the deep layer mixing treatment method, next, as shown in FIG. 1B, the improved ground 1 is moved to the depth position D ₁ of the slab bottom, that is, the underground to be constructed. Excavate to the ceiling level of structure A. Subsequently, as shown in FIG. 1C, the slab concrete 2 is placed on the bottom of the excavation to build the concrete. However, in preparation for further excavation and other work of the improved ground 1 that follows,
It is preferable to form an opening in the slab concrete 2.

Since the slab concrete 2 is used as a girder when the excavation of the improved ground 1 below the slab concrete 2 is carried out, the slab concrete 2 should be large enough to cover the underground structure A to be constructed in plan view. In addition, it is constructed so as to exert sufficient strength against earth pressure, groundwater pressure, etc. acting on the side wall 4 of the excavated portion.

After the slab concrete 2 develops the strength, the slab concrete 2 is utilized as a cutting beam, and as shown in FIGS. 1D and 1E, the improved ground 1 at the lower portion corresponds to the space corresponding to the underground structure A. Excavate. Then, as shown in FIG. 1F,
Finishing 6 such as shotcrete (spraying) on the side wall (inner wall) 3 and bottom wall (floor) 5 of the completed space, and further backfilling the excavated portion 8 above the slab concrete 2 to build an underground structure A. To complete.

As described above, in the method for constructing an underground structure according to the present invention, since the improved ground 1 improved by the deep mixing method is used mainly for the structure, the material for constructing the underground structure A is It is possible to save labor and reduce costs.

2 and 3 show different embodiments of the method for constructing an underground structure according to the invention described in claim 1. This embodiment is preferably implemented when constructing a long underground structure such as a so-called open-air underground road (highway or the like) or a waterway.

In this construction method for an underground structure as well, first, by the deep mixing method, the ground 11 for constructing the underground structure B is subjected to internal and external forces (earth pressure, groundwater pressure and vertical load) acting on the underground structure B. Etc.) to the extent that it can bear (horizontal direction and depth direction range) ground improvement (Fig. 3A).

Next, the improved ground 11 is excavated to the depth position D _X of the slab bottom, that is, the ceiling level of the underground structure B to be constructed, and the slab concrete 12 is constructed at the bottom of the excavation (FIG. 3B).

A feature of this embodiment is that the slab concrete 12 is constructed at the ground level (GL). Therefore, when the underground structure B is an underground road, the slab concrete 12 can be expected to function as a bridge that crosses the road. Therefore, slab concrete 1
No. 2 can be constructed not only when it is built on the entire upper surface of the underground structure B, but also at intervals such that it does not lose its role as a post beam (Fig. 2). Therefore, the above-mentioned interval portion can be used as an opening when excavating the improved ground.

After the slab concrete 12 develops its strength, it is used as a cross beam to excavate the improved ground 11 below by a space corresponding to the underground structure B, as shown in FIGS. 3C and 3D. Then, the improved ground 11 is used as it is for the side wall 13 and the bottom wall 15 to construct an underground structure B. And
As shown in FIG. 3E, finishing 16 such as shotcrete (spraying) is performed on the side wall 13 and the bottom wall 15 of the completed space to complete the construction of the underground structure A.

Therefore, according to the method for constructing an underground structure according to the present invention, the same operational effect as that of the method for constructing an underground structure A described with reference to FIG. 1 can be obtained. That is, since the improved ground 11 improved by the deep layer mixing method is used mainly for the structure, waste of materials and labor for constructing the underground structure B again can be omitted, and the cost can be reduced.

4A to 4D show an embodiment of a method for constructing an underground structure according to the invention described in claim 2. This is a suitable construction method when the underground structure C has a large scale and a pillar for supporting the slab concrete is required.

In the case of the present invention, prior to the step of excavating the improved ground 21 improved by the deep layer mixing processing method to the depth position of the slab bottom, an area suitable for supporting the slab concrete 22 (illustrated example) Then, the column core material 7 of H steel or the like is built in at a substantially central position of the cross section when viewed in plan. After that, the slab concrete 22 is constructed and supported by the pillar core material 7. Next, the excavation of the improved ground 21 below the slab concrete 22 is advanced to finish the inner wall 23, the floor 25 and the like of the excavated space and the pillar core material 7 (the invention according to claim 2). .

This construction method of the underground structure C is preferably carried out when the slab concrete 22 to be constructed has a long fulcrum and the column core material 7 must be provided. Since the supporting force of the slab concrete 22 can be secured by providing the pillar core material 7, the improved ground 21 below can be stably excavated, and the stability of the underground structure itself can also be obtained.

Although the embodiments have been described above with reference to the drawings, the present invention is not limited to the embodiments shown in the drawings, and the design changes and applications that a person skilled in the art normally makes within the scope not departing from the technical idea thereof. Note that it includes a range of variations of.

[0029]

[Effects of the Present Invention] According to the construction method for an underground structure according to the present invention, the following effects can be obtained. 1) The improved ground, which has been improved by the deep-mixing method, is used for the structure as a whole. Therefore, it is possible to save the waste of materials and labor for constructing the underground structure again, contribute to cost reduction, and of course, it has excellent seismic performance. It enables the construction of so-called long underground structures. 2) Since the ground for constructing an underground structure is improved first, it is not necessary to take measures against liquefaction and soft ground. 3) Since slab concrete plays the role of a cutting beam,
It does not require support work or earth retaining work and the wall thickness of the improved ground can be made thinner than when using it as a self-supporting earth retaining structure, which is economical. 4) When performing superstructure work, superstructure work can be performed after slab concrete construction, thus shortening the overall construction period. 5) When carrying out backfilling work, the excavated soil can be backfilled to the place where the concrete slab installation has been completed.
It is possible to simplify the treatment of residual soil. 6) Slab concrete can also be used for bridges. 7) Even if the excavation width is wide and the slab concrete fulcrums are long, it is possible to stably construct the underground structure by providing the pillar core material.

[Brief description of drawings]

1A to 1F are explanatory views showing, step by step, an embodiment of a method for constructing an underground structure according to the invention described in claim 1.

FIG. 2 is a perspective view showing a different embodiment of a method for constructing an underground structure according to the invention described in claim 1.

3A to 3E are explanatory views showing an embodiment of a method for constructing an underground structure according to the invention described in claim 1 step by step.

4A to 4D are explanatory views showing stepwise a construction method of an underground structure according to the invention described in claim 2.

FIG. 5 is an elevational view showing the prior art.

[Explanation of symbols]

A, B, C underground structure 1, 11, 21 ground 2,12,22 Slab concrete 3, 13 Side wall of underground structure 4,14 Side wall of excavation part 5,15 Bottom wall of underground structure 6, 16 finish 7 excavation section 8 pillar heartwood

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Norito Mori             8-21-21 Ginza, Chuo-ku, Tokyo Stock market             Takenaka engineering works F-term (reference) 2D047 AB04

Claims (2)

[Claims] 1. A step of improving the ground for constructing an underground structure by a deep-mixing method to the extent that the internal and external forces acting on the underground structure can be borne, and excavating the improved ground to the depth of the slab floor. A step of constructing a slab concrete, and after the slab concrete develops a required strength,
Utilizing this as a truss, the improved ground below is excavated for the space equivalent to the underground structure, and the inner wall and floor of the space are finished to complete the underground structure. Construction method for underground structures. 2. Prior to the step of excavating the improved ground, which has been improved by the deep mixing method, to the depth of the slab bottom, H at an appropriate site for supporting the slab concrete.
After constructing pillar core material such as steel, and then constructing slab concrete to be supported by the pillar core material, then proceed with excavation of the improved ground below the slab concrete, and finish the inner wall of the excavated space, floor, etc. The method for constructing an underground structure according to claim 1, wherein: