JPH10306680A - Pipe roofing method for excavation of ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve workability through reduction of the number of drives by increasing the strength of a ground region itself equivalent to the upper outer periphery of the top cover of an excavation space. SOLUTION: Boring holes 11 arranged in a roof-form manner at intervals of a proper distance in the upper outer periphery of an object to be excavated region 1a are excavated. After, by forcibly expanding each boring hole 11, density of a periphery ground region 1c is increased, a steel pipe 5 for reinforcement having diameter larger than that of the boring hole before expansion is inserted in an expanded boring hole 11 and anchored by a mortar 6. Excavation of an object to be excavated region 1a of a ground 1 is effected after a series of processes described above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to
When constructing an underground excavation space such as a large section tunnel,
The present invention relates to a pipe roof construction method for reinforcing the ground in an area serving as a roof portion and suppressing loose displacement of the ground due to excavation.

[0002]

2. Description of the Related Art When a tunnel or the like is excavated in a ground, a loose displacement occurs due to a release of stress accompanying the excavation in the ground in an area serving as a roof. As a construction method for minimizing such loosening of the ground as much as possible, a reinforcement construction method called a so-called pipe roof construction method has been conventionally known.

[0003] According to the conventional pipe roof method, for example, when a tunnel is excavated in the ground, a reinforcing steel pipe is placed in advance in the ground along the upper outer periphery of the excavation target area of the tunnel. A roof-like reinforcing steel pipe row (pipe roof) is formed by arranging in an arc shape and being substantially parallel to the excavation direction of the tunnel. Then, after the inner peripheral side of this reinforcing steel pipe row is excavated to construct a tunnel, a shoring is built in, and the reinforcing steel pipe row is directly supported, so that the upper ground accompanying the excavation of the tunnel is constructed. This is to prevent the mountain from loosening.

[0004]

However, the pipe roof construction method according to the prior art described above requires a large number of reinforcing steel pipes because the reinforcing steel pipes are driven close to each other, so that a large number of reinforcing steel pipes are required. It takes a lot of time,
The material cost is also high, and the reinforcing steel pipe is liable to bend and deform during driving, and thus has a problem in workability.

The present invention has been made in view of the above circumstances, and a technical problem thereof is to increase the strength of the ground itself, which is a roof region of a digging space such as a tunnel. Accordingly, an object of the present invention is to provide a construction method capable of reducing the number of steel pipes for reinforcement and improving workability.

[0006]

As a means for effectively solving the above-mentioned technical problems, a pipe roof construction method for ground excavation according to the present invention firstly uses a ground roof above a region to be excavated in an excavation space. Boring holes arranged in a roof shape at appropriate intervals in a region corresponding to the outer periphery of the roof of the excavation space are drilled substantially parallel to the excavation direction. Next, the ground around the boring hole is compressed at a high density by forcibly expanding the diameter of each of the boring holes, and then the diameter of the boring hole is increased within the expanded boring hole. A reinforcing steel pipe having a diameter is inserted, and a solidifying material such as mortar is filled between the inner wall of the boring hole and the reinforcing steel pipe. The step of forming the excavation space by excavating the excavation target area of the ground is performed after the above-described series of steps is completed.

[0007] According to this method, the ground area itself, which is the roof portion of the excavation space formed by excavating the excavation target area of the ground, has a high density due to the diameter expansion of each boring hole and has a high strength. Is increased, and a reinforcing steel pipe is poured into each of the boring holes and is fixed with a solidifying material.Therefore, the pipe roof having high rigidity due to the high-density ground area and the reinforcing steel pipe row is It is formed so as to surround the upper side of the excavation target area. For this reason, compared with the conventional construction method which depends only on the rigidity of the reinforcing steel pipe, the spacing between the reinforcing steel pipes can be widened and the number of the reinforcing steel pipes can be reduced.

In the present invention, in order to increase the diameter of the boring hole, for example, a variable-capacity sealed bag made of a polymer material having flexibility or rubber-like elasticity is inserted into the boring hole, and the inside of the bag is inserted. For example, a method in which a pressurized fluid is press-fitted into the container is suitably employed. According to this method, the inner wall of the boring hole can be uniformly pressed and expanded by the pressure applied to the pressurized fluid from outside the boring hole.

[0009]

1 to 4 show a preferred embodiment in which a pipe roof method according to the present invention is applied to the construction of an underground space by excavation of a ground, in the order of steps, and FIG. () Is a schematic explanatory view of a construction mode, and (B) is a cross-sectional view of the ground cut along the line BB 'in (A).

First, FIG. 1 shows a process of drilling a boring hole in a ground. Reference numeral 1 denotes a ground to be excavated. An excavation target area for forming an excavation space 12 (see FIG. 4);
2 is a base constructed of a steel frame or the like for installing a boring machine, a pressurized water supply device, a steel pipe insertion machine, etc. on the starting side of excavation of the ground 1, and 3 is a guide for inserting a reinforcing steel pipe 5 described later. It is a sentence ruler to be used as a means.

In this drilling step, a boring machine is installed on the base 2 and the rod 21 is propelled toward the interior of the ground 1 while rotating the rod 21 so that the bit 21a at the tip of the boring machine can be applied to the ground 1. The boring hole 11 is drilled. This boring hole 11 is located on the upper side of the excavation target area 1a and the roof 12a of the kamaboko-shaped excavation space 12 shown in FIG.
Holes are drilled in an area 1b corresponding to the outer periphery of the excavation space 12 at an appropriate interval in a roof shape (arc-like shape) and substantially parallel to the excavation direction of the excavation space 12.

Next, as shown in FIG.
A pressure bag 4 which is an elongated closed bag made of a flexible or elastic material such as rubber or soft plastic having high airtightness is inserted into the inside of the pressure bag 4. The apparatus is connected via a water supply pipe 22, and an exhaust / drain pipe (not shown) having a valve device is connected. Then, water W as a pressure medium is supplied from the pressurized water supply device through a water supply pipe 22, and the remaining air in the pressure bag 4 is discharged through the exhaust / drain pipe to discharge the water W. Fill the pressure bag 4. And
When the water W is filled in the pressure bag 4, the exhaust
The valve device in the drainage pipe is closed, and the water W is further pressurized to expand the pressure bag 4.

The inflated pressure bag 4 is pressed against the inner wall surface of the boring hole 11 and is pushed and spread radially as indicated by a number of arrows in the figure. As a result, as shown by the broken line in the figure, as the diameter of each boring hole 11 expands, a certain range of the ground area 1c around the hole 11 is compressed and densified, thereby increasing its strength.

The step of pressurizing and expanding the borehole 11 by the pressure bag 4 will be described in more detail with reference to FIG. 5. A number of water supply holes 22 a are opened near the tip of the water supply pipe 22. . Further, the pressure bag 4 has a water supply pipe 22 having a tip end via a cone 23.
The water supply hole 22a surrounds the outer peripheral side of the portion where the water supply hole 22a is opened, and the rear end is fixed at a predetermined axial position on the outer periphery of the water supply pipe 22 via a collar 24.

For this reason, as shown in FIG. 5A, when the water supply pipe 22 is inserted into the boring hole 11, the collar 24 eventually interferes with the ground 1, so that only the mounting portion of the pressure bag 4 is provided. Is inserted. Then, in this state, the inside of the pressure bag 4 is supplied with water and pressurized from the water supply pipe 22 through the water supply hole 22a. At this time, the collar 24 has a function of preventing the pressure bag 4 from expanding in the axial direction toward the outside of the boring hole 11 due to water pressure. As shown in FIG.
When the portion near the inlet of the airbag is expanded to a predetermined inner diameter into which the collar 24 can be inserted, the pressure in the pressure bag 4 is released once, and the water supply pipe 22 is further connected to the boring hole 11 as shown in FIG. Insert it toward the back. And color 2
After the hole 4 has been inserted until it interferes with the step surface 11a between the enlarged diameter portion of the boring hole 11 and the non-increased diameter portion, a process of supplying water and pressurizing the pressure bag 4 again is repeated.

In FIG. 2B, the densified ground areas 1c around each of the enlarged boring holes 11 are separated from each other. Depending on the water pressure, the ground area 1c is formed in a state of being continuous with each other. Further, the inside of the pressure bag 4 is pressurized so that the inner diameter of each boring hole 11 is expanded to be larger than the outer diameter of the reinforcing steel pipe 5 described later.

When the entire length of each borehole 11 in the longitudinal direction is expanded, the pressurization in the pressure bag 4 by the pressurized water supply device is stopped, and the valve device of the exhaust / drain pipe is opened to open the pressure bag 4. , The pressing of each boring hole 11 against the inner wall surface is released. Then, after removing the pressure bag 4 and the pipes and the like, as shown in FIG. 3, the reinforcing steel pipe 5 is inserted into each of the bore holes 11 whose diameter has been increased.

The reinforcing steel pipe 5 has a diameter larger than the diameter of the boring hole 11 before the diameter expansion shown in FIG. 1, and its insertion operation is guided by a centrifuge ruler 3 by a steel pipe insertion machine installed at the base 2. It is done while. Mortar 6 is filled between the inner wall surface of the boring hole 11 and the inserted reinforcing steel pipe 5 as a solidifying material.

The reinforcing steel pipe 5 inserted into each of the boring holes 11 is connected to the inner wall surface of each of the boring holes 11 via the mortar 6 which hardens with time, that is, the dense ground around each of the boring holes 11. The image is fixed integrally with the region 1c. Since the reinforcing steel pipe 5 has a larger diameter than the boring hole 11 before the diameter expansion, the diameter of the boring hole 11 is prevented from being reduced to the state before the diameter expansion, and the high-density state of the region 1b is maintained. At the same time, the reinforcing steel pipe 5 itself has a required rigidity. And this results in FIG.
As shown in (B), the rigidity of the ground region 1c, which has been increased in density and increased in strength, and the row of reinforcing steel pipes 5 integrated with the ground region 1c via the mortar 6 are large. The pipe roof 7 is formed so as to surround the upper side of the excavation target area 1a in a roof shape.

After the series of steps described above are completed and the mortar 6 is completely hardened, the excavation area 1a in the ground 1 is excavated to form an excavation space 12 as shown in FIG. This excavation is performed at every predetermined distance L, and a shoring (lining) 8 having a predetermined thickness by spraying mortar or the like is performed as necessary in order to prevent minute collapse on the roof 12a.

According to the above embodiment, the pipe roof 7 formed along the outer periphery of the upper part of the roof 12a of the excavation space 12
To support the load of the ground above it,
2. Suppress looseness of the upper ground. Since a part of the supporting force of the pipe roof 7 is taken up by the densified ground region 1c around the reinforcing steel pipe 5, the spacing between the reinforcing steel pipes 5 is supported only by the reinforcing steel pipe 5. This can be larger than in the conventional method, so that the number of reinforcing steel pipes 5 can be reduced as compared with the conventional method in which the ground is supported only by the steel pipe.

[0022]

According to the pipe roof construction method of the present invention, the diameter of the boring hole is increased and the surrounding high density ground area and the reinforcing steel pipe inserted and fixed in the boring hole are formed. Synergy with rigidity suppresses loosening due to ground excavation, so that the following hardening is realized. (1) The number of steel pipes used for reinforcement is reduced compared to the conventional method, and material costs can be reduced. (2) Construction time can be reduced by saving steel pipes for reinforcement. (3) Since the steel pipe for reinforcement is inserted into a boring hole having a larger diameter, bending deformation of the steel pipe for reinforcement unlike the conventional method does not occur.

[Brief description of the drawings]

FIG. 1 shows a boring hole drilling step in a preferred embodiment of a pipe roof method according to the present invention;
(A) is a schematic explanatory view of this step, and (B) is a cross-sectional view along the line BB 'in (A).

FIG. 2 shows pressurization of each boring hole in the embodiment.
4A and 4B show a diameter expansion step, in which FIG. 4A is a schematic explanatory view of this step, and FIG. 4B is a cross-sectional view along the line BB ′ in FIG.

FIG. 3 shows a step of inserting a steel pipe into a boring hole and filling a mortar between the boring hole and an inner wall of the boring hole in the embodiment, (A) is a schematic explanatory view of this step, and (B) FIG. 3 is a cross-sectional view taken along line BB ′ in FIG.

FIGS. 4A and 4B show a state in which an underground space is excavated after the completion of the construction of the pipe roof according to the above embodiment, wherein FIG. 4A is a schematic explanatory view of this state, and FIG.
It is sectional drawing which followed the B 'line.

FIG. 5 is an explanatory view showing in detail a pressurizing and expanding step of the boring hole of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ground 1a Excavation target area 1b Area corresponding to outer periphery of a roof 11 Boring hole 12 Excavation space 12a Roof 4 Pressure bag 5 Steel pipe for reinforcement

Claims (2)

[Claims] 1. A boring hole arranged in a roof shape at an appropriate interval in an area corresponding to an outer periphery of a rooftop of the excavation space, which is located above a region to be excavated in the excavation space. Drilling substantially parallel to the direction, and forcibly expanding the diameter of each boring hole to compress the ground around the boring hole with high density. Earth excavation, comprising: inserting a reinforcing steel pipe having a diameter larger than that of the boring hole before diameter expansion and filling a solidifying material between the inner wall of the boring hole and the reinforcing steel pipe. Pipe roof method. 2. The method according to claim 1, wherein the diameter of the boring hole is increased by inserting a variable-capacity sealed bag made of a polymer material having flexibility or rubber-like elasticity into the boring hole. A pipe roof construction method in ground excavation, which is performed by pressurizing a pressurized fluid into the bag body.