JPH0696934B2 - Large-section cavity structure and excavation method for large-section cavity - Google Patents

Description

TECHNICAL FIELD The present invention relates to a large-section excavation method, and more particularly to a large-section large-cavity structure at a large depth and its excavation method that is simple and can be realized.

<Prior Art> The maximum diameter of the shield machine currently used is 14 m, but if this is excavated by a shield machine with a diameter of 20 m or more, the following problems are raised.

Since a large cross-section cavity is excavated at one time, the loosening range of the rock mass increases, resulting in ground subsidence and excessive ground pressure acting on the shield machine, which may eventually cause the rock mass to collapse. There is.

A high-rigidity shield machine is required to counter the large earth pressure and water pressure, which not only raises the manufacturing cost, but also causes many problems in transportation and assembly. Especially when the extension of the tunnel is short, the construction cost is high and it is difficult to adopt.

In addition, since there is no actual record, there is concern about the application of the shield construction method with a diameter of 14 m or more.

On the other hand, conventional construction methods for constructing large cross-section cavities in alluvial ground, that is, pre-receiving construction methods such as pipe roof construction methods, and construction methods for concrete structures in which concrete columns are horizontally pressed in from the outside can be considered. However, in the above construction method, the process of carrying out first reception, excavation, and lining is complicated and the construction cost becomes high. In addition, if the water level is high, an auxiliary construction method is also required. Further, above all, it is impossible to obtain a large-section cavity structure by the conventional method because the large-section cavity is formed at a large depth due to excessive ground stress.

<Problems to be Solved by the Invention> The present invention has been made in order to solve the above-mentioned drawbacks, and the purpose thereof is to be able to sufficiently withstand the earth pressure even if the water pressure is large, and the soft ground with a high water level. Above all, it can be easily constructed by simple technology such as expanding and designing conventional technology,
Moreover, it is to provide a large-section cavity structure that can safely construct a large-section cavity without collapsing the tunnel wall surface and an excavation method therefor.

<Means for Solving the Problems> The present invention is intended to solve the above-mentioned problems, and the gist thereof is a tunnel structure having a large cross-section cavity, which structure has the large cross-section cavity. The structural wall body that has a large number of shield tunnels formed by casting concrete inside in the axial direction of the outer periphery of the ring, and by polymerizing a reinforcing material such as a chemical solution or a backing material on the outside of the shield tunnel, A large-section cavity structure including a reinforcing portion integrally formed on the outer periphery of the large-section cavity, the large-section cavity formed by excavating the inside of the structure, and a lining body in which the inner surface of the large-section cavity is lined with concrete. It is in.

Further, as another gist of the present invention, a large number of shield tunnels are provided by a shield machine in the axial direction of the outer periphery of the planned large-section cavity, and a reinforcing material such as a chemical solution or a backfill material between each shield tunnel and the ground. And a step of forming an annular structure while injecting, and a step of forming a toroidal structure by filling or lining concrete in each of the shield tunnels with or after this step, followed by this step, There is a large-section cavity excavation method including a step of excavating the large-section cavity in the annular structure and a step of lining concrete on the inner surface of the large-section cavity.

<Operation> In the present invention, first, a reinforcing material such as a chemical solution or a backfill material is polymerized between shield tunnels by a shield construction method using a shield machine, and excavated around a planned large cross-section cavity, By constructing an annular structural wall body by lining concrete on it, it becomes possible to subsequently excavate a large cross-section cavity in this reinforced structural wall body, and the water pressure causes flooding in the tunnel against earth pressure. We will form a large cross-section cavity that is safe and effective while preventing the collapse of the ground.

<Example> A large cross-sectional cavity structure according to the present invention and a method of excavating the same will be described below with reference to the drawings.

FIG. 1 is a schematic vertical cross-sectional view showing one embodiment of the large cross-section cavity structure of the present invention, and FIG. 2 is a partially cutaway perspective view of FIG. In the figure, there is an annular structural wall body 2 that is connected without gaps to the outer periphery of a planned large cross-sectional cavity 3. This structural wall body 2 is an annular structure in which a large number of shield tunnels 1 are connected in an annular shape. Lined or filled with concrete. In addition, the large cross-section cavity 3 is mechanically or manually excavated inside the structural wall 2, and the excavated surface is made of concrete, steel, or synthetic segment, cast concrete, or lining by concrete spraying. Has been done. Further, a chemical solution or a backfill material is injected between each of the shield tunnels and the ground to form the shield tunnels integrally with each other to strengthen the structural wall body 2 and to improve the water stopping property.

In the case of excavating the shield tunnel, if the ground to be excavated is soft ground, it is possible to form the ground improvement zone 4 by injecting a chemical solution to the outside of each shield tunnel.

The procedure for constructing the large-section hollow structure of the present invention having the above structure will be described below.

First, the horizontal hole 1 formed by a large number of shield tunnels is continuously excavated in an annular shape along the outer periphery of the planned excavation cross section of the large cross section cavity.

In this case, the inside of the horizontal hole 1 is lined or filled with a segment, cast-in-place reinforced concrete body,
Further, the inside of the structure is lined with concrete or steel segment 5 or cast in place or sprayed concrete to reinforce the structure wall, and a continuous annular structure wall 2 having no gaps. To build. For these horizontal holes 1 to be continuously excavated in an annular shape, a construction technique in which adjacent horizontal holes 1 are polymerized and connected by a reinforcing body such as soil cement or chemical liquid injection is applied. It is essential that they are structurally continuous by using them together.

Then, the inside surrounded by the continuous annular structural wall body is sequentially excavated to form a large-section cavity. At that time, if the structural wall alone is insufficient for reinforcement against water pressure, earth pressure, etc. acting on the structural wall, the improvement zone 4 improved on the ground by a method such as chemical injection is provided on the outside of the structural wall. It can also be formed.

In this case, the conventional tunnel excavation method can be applied to the excavation method and the method of carrying out the excavated scrap. Further, when the face is soft or easily broken due to water pressure or the like, a method of injecting a chemical solution to the outer periphery of the face, air pressure, freezing, mud or earth pressure shield is applied.

<Effects of the Invention> Before excavating the large cross-section cavity of the present invention in the horizontal direction, a continuous annular annular structural wall that resists water pressure and earth pressure is constructed before the excavation. It becomes possible to construct a large-section cavity by excavating the enclosed inside safely and surely.

The present invention thus configured has the following features.

Since a continuous annular structural liquid is constructed around the outer periphery of the planned large-section cavity, a large-section horizontal cavity can be safely constructed without wall collapse or water intrusion, which is particularly effective in soft ground.

In particular, since the annular structural wall body is preliminarily drilled by the shield tunnel, it is possible to easily perform the construction by the conventional technique even on the soft ground with a high water level.

In addition, by injecting a chemical or a reinforcing material such as a backfill material between each adjacent shield tunnel and the ground and polymerizing them integrally, it functions as an annular cross section, which is advantageous in terms of stress and also waterproofing. Get higher

Furthermore, since concrete lining is applied to the inner surface of the large-section hollow inside the annular structural wall body, it is possible to obtain a strong large-section hollow structure that can sufficiently cope with excessive ground stress.

Even if the excavation length is short and it is uneconomical to put in a large cross-section shield machine, this method can be used for economical construction.

Even if the conditions are harsh and the water pressure is extremely soft and the cutting face is not stable in a large cross section, the ground improvement zone can be formed outside the shield tunnel, so it is possible to deal with it.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a large-section cavity structure of the present invention. FIG. 2 is a partial perspective view of FIG. 1 ... horizontal hole (shield tunnel), 2 ... annular structural wall, 3 ... large cross-section cavity, 4 ... improved zone by injection of chemicals or freezing, 5 ... from concrete or steel segment, etc. Become a lining.

Claims (2)

[Claims] 1. A tunnel structure having a large cross-section cavity, which is a structure in which a large number of shield tunnels, in which concrete is placed inside in the axial direction of the outer periphery of the large cross-section cavity, are annularly constructed. A wall, a reinforcing portion integrally formed on the outer periphery of the large cross section cavity by polymerizing a reinforcing material such as a chemical solution or a backfill material on the outside of the shield tunnel, and the inside of the structure excavated A large-section cavity structure consisting of a large-section cavity and a lining body whose inner surface is lined with concrete. 2. A large number of shield tunnels are axially provided in the outer circumference of a planned large cross-section cavity by a shield machine while injecting a chemical solution or a backing material between the shield tunnels and the ground. A step of constructing in an annular shape, a step of filling or lining concrete in each of the shield tunnels to form an annular structure after or together with this step, and following this step, the annular structure A method of excavating a large-section cavity, the method including the step of excavating the large-section cavity, and the step of lining concrete on the inner surface of the large-section cavity.