JP2002309884A - Structure and method for steel pipe forepoling work for tunnel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of steel pipe forepoling construction for a tunnel capable of improving workability and shortening the term of works, the reduction of a material cost and an execution cost or the like in addition to the sure reinforcement of a ground by using the steel pipe having a smaller bore than conventional devices when the ground in front of an excavation face is reinforced prior to the excavation of the tunnel, and a tunnel structure by its method. SOLUTION: A plurality of the steel pipes 1, 1 and the like are arranged zigzag on the ground 6 within an angle range of approximately 120 deg. to a tunnel center 0 along the top face of the tunnel 7. A continuous arched cured body 11 is formed to the upper section of the tunnel 7 by setting disposal spaces in spaces continuing to the adjacent cured regions 10', 10' and the like of the cured regions 10', 10' and the like formed around each steel pipe 1, 1 and the like by a curing agent in this case, and earth-pressure load from the ground 6 is borne by the arched cured body 11 strengthened by a wedge arch effect. When the ground 6 in the lower sections of both end sections of the arched cured body 11 is particularly weak, the steel pipes 12 and 12 for reinforcement are disposed to sections continued from both end sections of the arched cured body 11 at both end sections of the tunnel 7 to lower sections.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for pre-excavation of a tunnel in which a ground in front of an excavation face is reinforced before excavation of the tunnel and a structure of the tunnel by a pre-existing steel pipe method. Belongs to the field.

[0002]

2. Description of the Related Art When excavating a tunnel, the ground in front of the excavation face is reinforced before excavation in order to prevent loosening of earth, sand, rocks, rocks and the like forming the excavated tunnel wall. The method of excavating the tunnel using a steel pipe tip receiving method is used.

In this method, a steel pipe is struck from the periphery of a tunnel excavation face into the ground in a slightly forward and obliquely outward direction by hitting the rear end of the steel pipe, and the steel pipe is struck from the rear end of the steel pipe to the ground. The improvement of the ground by injecting a hardening agent and the rigidity of the steel pipe reinforce the ground in front of the excavation face and excavate the tunnel.

[0004]

By the way, in the above-mentioned steel pipe tip receiving method, as shown in FIG.
Is calculated with respect to the earth pressure load F from the ground B as a beam having the support C and the ground B at the tip of the steel pipe A as a fulcrum. Therefore, in order to suppress the deflection as a beam, it is necessary to make the steel pipe A large in diameter or to narrow the interval P between the supports C ... C.

[0005] Therefore, the steel pipe A used has a large diameter, so that the weight is heavy and the workability of transportation and the like is poor. Particularly in tunnel excavation, since the steel pipe A may be handled at a high place, it is not preferable in terms of workability that the weight of the steel pipe A is heavy. Further, since it takes a long time to drive such a large-diameter steel pipe A, there is a problem in terms of shortening the construction period. In order to drive the steel pipe A into the ground B, a special steel pipe driving device is required.

[0006] On the other hand, when the interval P between the supports C is reduced, the excavation pitch becomes narrower, which poses a problem in terms of reducing material costs and construction costs.

[0007] In view of the above-mentioned problems when reinforcing the ground in front of the excavation face prior to excavation of the tunnel, the present invention makes it possible to use a steel pipe having a smaller diameter than before. In this way, it is possible to improve the workability, shorten the construction period, and reduce material and construction costs while ensuring the reinforcement of the ground. It is an object to provide a structure.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention is characterized in that it is configured as follows.

First, according to the first aspect of the present invention, prior to excavating a tunnel, a plurality of steel pipes are inserted from the periphery of the excavation face into the ground in a slightly obliquely outward direction.
A method of injecting a hardening agent into the ground through the inside of the steel pipe from the rear end of these steel pipes and thereafter digging the face forward, in which the steel pipe has a substantially semicircular cross section along the top surface of the tunnel. And the arrangement interval is set such that the hardened region formed around each steel pipe by the hardening agent is continuous with the adjacent hardened region, so that an arch-shaped portion is continuously formed at the top of the tunnel. It is characterized by forming a cured body.

According to the present invention, since the steel pipes are arranged at a continuous interval between the hardened areas formed around the steel pipes by the injected hardening agent and the adjacent hardened areas, the steel pipes and the steel pipes are provided above the tunnel. A continuous arched cured body is formed by gathering the surrounding cured regions, and the entire arched cured body is firmly integrated by a so-called wedge arch effect. Therefore, the arch-shaped hardened body surely supports the earth pressure load from the ground, and the reinforcement of the ground is surely achieved.

In this case, since a small-diameter steel pipe can be used to support the earth pressure load by the action of the wedge arch effect, the steel pipe has a single weight as compared with a conventional large-diameter steel pipe. Is lightweight, so that the steel pipe to be used is easily transported. In addition, since these steel pipes are handled even at a high place, it is very preferable that the steel pipes used are lightweight, and the workability is improved.

Further, since the used steel pipe has a smaller diameter than the conventional steel pipe, the required driving time is shortened. Therefore, the construction period can be shortened. Further, in this case, the steel pipe driving device used for driving the steel pipe does not need to be a special device, so that the construction cost can be reduced.

Further, since the steel pipes are arranged at a continuous interval between the hardened areas formed around the steel pipes by the injected hardening agent and the adjacent hardened areas, there is almost no gap between these hardened areas. Therefore, there is almost no possibility that earth and sand, rocks, and the like above these hardened regions fall into the tunnel, and the workability is maintained.

Next, according to a second aspect of the present invention, in the method for pre-receiving a steel pipe of a tunnel according to the first aspect, a resin pipe is connected to a rear end portion of the steel pipe when the steel pipe is inserted. It is characterized in that a hardening agent is injected from an end portion, and a portion of the resin pipe projecting into an excavation region is removed when excavating a face.

According to the present invention, since the resin pipe is connected to the rear end of the steel pipe and inserted into the ground, the steel pipe can be driven until the rear end is located outside the excavation area in front of the face. . By projecting the rear end of the resin pipe into the excavation area, the hardener can be injected into the ground from the rear end through the steel pipe. In addition, since the resin pipe protrudes into the excavation area, the face can be excavated together with the resin pipe when excavating the face.
Therefore, no extra digging is required, which can reduce material costs and construction costs.

According to a third aspect of the present invention, in the method for pre-receiving a steel pipe of a tunnel according to the first or second aspect, the plurality of steel pipes are arranged in a staggered manner on the cross section of the tunnel. Features.

According to the present invention, since a plurality of steel pipes are arranged in a staggered manner on the cross section of the tunnel, a stronger arched hardened body is formed, and the reinforcement of the ground is more reliably achieved. Become so.

According to a fourth aspect of the present invention, there is provided the steel pipe pre-receiving method for a tunnel according to any one of the first to third aspects, wherein both sides of the tunnel are lower than both ends of the arched hardened body. The reinforcing member is disposed substantially radially on the cross section of the tunnel in a portion following the above.

According to the present invention, since the reinforcing member is provided on both sides of the tunnel below the both ends of the arched hardened body, the ground below both ends of the arched hardened body is particularly soft. Even in such a case, the arched hardened body and the reinforcing member can reliably support the earth pressure load from the ground.

Further, the invention according to claim 5 is characterized in that in the method for pre-receiving a steel pipe of a tunnel according to any one of claims 1 to 4, the curing agent contains a fiber material. I do.

According to the present invention, since the curing agent contains a fibrous material, a stronger arched cured product is formed by a so-called fiber reinforcement mechanism. That is, as long as the earth pressure load from the ground acts uniformly on the arched hardened body, a compressive force is generated in the arched hardened body,
When the earth pressure load acts unequally, the partial pressure may generate a tensile force locally in the arched hardened body. Generally, it is considered that a hardening agent such as cement is strong in compressive force but weak in tensile force.However, by adding a fiber material to this hardening agent, an arched hardened material having strong tensile force can be obtained. The advantage of the above configuration is further ensured.

In the invention according to claim 6, a plurality of steel pipes are inserted from the periphery of the excavation face into the ground in a slightly forward and obliquely outward direction, and the steel pipes are inserted from the rear ends of the steel pipes into the steel pipes. It relates to the structure of a tunnel formed by injecting a hardening agent into the ground and then digging the face forward.The steel pipe is arranged in a substantially semicircular cross section along the top surface of the tunnel. Has been established,
The arrangement interval is such that the hardened region formed around each steel pipe by the hardener is a continuous interval with the adjacent hardened region, and a continuous arched hardened body is formed at the upper part of the tunnel. And

According to the present invention, similarly to the first aspect of the present invention, the entire arch-shaped hardened body is firmly integrated by the wedge arch effect, so that the earth pressure load from the ground is reliably supported. . In this case, a small-diameter steel pipe can be used to support an earth pressure load by the effect of the wedge arch effect.

Since hardly any gaps are formed between the hardened areas, there is almost no risk that earth and sand, rocks, etc. above these hardened areas fall into the tunnel.

According to a seventh aspect of the present invention, in the tunnel structure according to the fifth aspect of the present invention, the plurality of steel pipes are arranged in a staggered manner on the cross section of the tunnel. Features.

According to this invention, a plurality of steel pipes are arranged in a zigzag pattern on the cross section of the tunnel as in the third aspect of the invention, so that a harder arched hardened body is formed. And the reinforcement of the ground is more reliably achieved.

[0027] The invention according to claim 8 is directed to the structure of the tunnel formed by the steel pipe precedent method according to claim 6 or 7, wherein both sides of the tunnel are lower than both ends of the arched hardened body. In the subsequent part, a reinforcing member is arranged substantially radially on the cross section of the tunnel.

According to the present invention, similarly to the fourth aspect of the present invention, even when the ground below both ends of the arched hardened body is particularly soft, the arched hardened body and the reinforcing member are used. The earth pressure load from the ground can be reliably supported.

According to a ninth aspect of the present invention, in the structure of the tunnel according to any one of the sixth to eighth aspects of the present invention, the hardening agent contains a fiber material. It is characterized by being.

According to the present invention, as in the fifth aspect of the present invention, a harder arched cured product is formed by the fiber reinforcing mechanism. That is, an arch-shaped cured body having high tensile strength can be obtained, so that the merit of the above structure is further ensured.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a description will be given of a tunnel excavation by a non-widened steel pipe precedent method to which a steel pipe precedent method according to an embodiment of the present invention is applied, and a tunnel structure by the non-widened steel pipe precedent method.

First, as an example of a steel pipe used in this method, as shown in FIG. 1, a cylindrical steel pipe 1 has a plurality of injection holes 1a... It has a shape having a screw portion 1b on the inner peripheral surface of the portion (right side in the drawing).

A cylindrical resin pipe having a plurality of injection holes 2a... 2a at predetermined intervals in the longitudinal direction and a threaded portion 2b on the outer peripheral surface of the tip (left side in the drawing) of the steel pipe 1. 2 are connected by screwing the two screw portions 1b and 2b.

The drill 3 is rotatably attached to the distal end of the steel pipe 1 via mounting members 3a... 3a provided on the drill 3, and is inserted into the steel pipe 1 from the rear end of the resin pipe 2. The inserted rod 4 is detachably attached to the rear end of the drill 3.

Next, a description will be given of the excavation of a tunnel using the above-mentioned non-widening steel pipe tip receiving method.

First, as shown in FIGS. 2 and 3, in a state where the drill 3 is attached to the steel pipe 1, the drill 3 is connected to the steel pipe driving device 5 via the rod 4, The steel pipe 1 is set in the steel pipe driving device 5. The drill 3 is connected to a steel pipe driving device 5 via a rod 4.
From the ground to excavate the ground 6.

That is, the drill 3 attached to the tip of the steel pipe 1 is pressed against the periphery of the excavation face 8 of the tunnel 7, and the drill 3 is grounded by the rotational force given from the steel pipe driving device 5. While drilling the mountain 6, it penetrates into the ground 6 ahead at an angle of about 20 degrees with respect to the axis of the tunnel 7. In this case, the steel pipe 1 is drawn into the ground 6 by the driving force of the drill 3. Note that a method of driving the steel pipe 1 into the ground 6 by tapping the rear end of the steel pipe 1 can be used.

Next, the rear end of the steel pipe 1 is provided with an excavating face 8.
The rotation of the drill 3 is stopped when the drill 3 is retracted until it is positioned outside the front excavation area 9, and the rod 4 attached to the drill 3 is removed. In that case, the drill 3 is left in the ground 6 while being attached to the steel pipe 1, while
The rear end of the resin pipe 2 connected to the steel pipe 1 protrudes in front of the excavation face 8.

The above steps are repeated until a predetermined number of steel pipes 1... 1 are inserted into the ground 6. In that case,
As shown in FIG. 4, the steel pipes 1... 1 have an angle of about 120 degrees with respect to the center O of the tunnel in a state where the interval (center-to-center distance) is a predetermined interval d on the cross section of the tunnel 7. They are arranged in a staggered pattern within the range. The space d is a space in which a hardened region formed around each of the steel pipes 1... 1 by a hardener described later is continuous with an adjacent hardened region, and is set to about 60 cm as an example.

After the steel pipe 1 is drawn into the ground 6, the hardener is injected. That is, as shown in FIG. 5, an injection pipe set in an injection device (not shown) is inserted from the rear end of the resin pipe 2 connected to the steel pipe 1, and the ground reinforcement supplied from the injection device is used. A hardening agent 10 such as cement flows from injection holes 1a... 1a, 2a.
And is cured to form a cured region 10 '.

After the injected hardening agent 10 has hardened, the excavating face of the tunnel 7 together with the resin pipe 2 and the injection pipe (not shown) remaining in the excavating area 9 in front of the excavating face 8 by an excavator (not shown). 8 is excavated.

Here, the operation of the above-described embodiment will be described. The most characteristic point is that, as shown in FIG. 6, the upper part of the tunnel 7 has a steel pipe 1... 1 and a hardened area 10 formed around the steel pipe 1. ... Are assembled to form the arched cured body 11. That is, in the arched hardened body 11 as described above, assuming that this is a set of wedge-shaped hardened bodies 11a, the earth pressure load F from the ground 6 is applied to the arched hardened body 11 as shown in FIG. When acting from the surroundings, the wedge-shaped cured body 11
In (a), tangential forces f, f are generated on the surface in contact with the adjacent wedge-shaped hardened body 11a as a component of the load F, and these forces f, f press between the adjacent wedge-shaped hardened bodies 11a. As a result, the entire arched hardened body 11 is more firmly integrated by the so-called wedge arch effect.

That is, the above-mentioned concept is not based on the strength calculation using the steel pipes 1... 1 as beams, and is smaller than a conventional one (for example, an outer diameter of about 114 mm). Even when the steel pipes 1... 1 are used, the tunnel 7 is formed by the wedge arch effect of the arched hardened body 11.
The earth pressure load F from the upper ground 6 is reliably supported.

When the ground 6 below both ends of the arched hardened body 11 is particularly soft, as shown by phantom lines in FIG. On the section extending below both ends, other steel pipes 12 and 12 for reinforcement are substantially radially provided on the cross section of the tunnel 7.
Should be arranged. By doing so, the steel pipes 12, 12 supporting the arch-shaped hardened body 11 below both ends thereof can more reliably support the earth pressure load from the ground 6.

Further, each of the steel pipes 1... 1 is formed by a hardening agent 10 around each of the steel pipes 1.
10 'is arranged at a distance d which is continuous with the adjacent hardened areas 10' ... 10 ', so that there is almost no gap between the hardened areas 10' ... 10 '. Therefore, the upper ground 6
There is almost no possibility that earth and sand or rocks will fall into the tunnel 7 from above. When the permeability of the hardening agent 10 into the ground 6 is poor, the distance d between each other is about 60
cm, not 45 to 40 cm
Should be arranged.

Since the rear end of the resin pipe 2 remains in front of the excavation face 8, that is, in the excavation area 9 in front of the excavation face 8, the ground pipe 6 passes through the steel pipe 1 from the rear end of the resin pipe 2. It becomes possible to inject the curing agent 10 into the inside. After the hardening agent 10 is hardened, the excavation face 8 is excavated together with the resin pipe 2 remaining in the excavation area 9, thereby enabling the excavation of the tunnel 7 that does not require extra excavation.

In the above embodiment, the curing agent 1
0 was made of a material such as cement.
By incorporating the fibrous material into 0, a more rigid arched cured body 11 is formed by a so-called fiber reinforcement mechanism. That is, the arched cured body 1
Since 1 is also strong against tensile force, the merit of the above configuration is further ensured. For example,
When cement is used for the hardening agent 10, the fiber material contained in the cement is not required to be weak to alkali, and glass fiber or the like can be used as an example.

When the steel pipe 1 and the hardened area 10 ′ are viewed as beams supported by a support (not shown) and the ground 6 at the tip of the steel pipe 1, the steel pipe 1 deflects due to the earth pressure load from the ground 6. As a result, a tensile force is generated in the lower part of the beam along the longitudinal direction. In this case, since the hardened region 10 'is formed of the hardening agent 10 containing a fibrous material, it is expected that the hardening region 10' is enhanced against this tensile force.

In the above-described embodiment, the non-widened steel pipe tip receiving method has been described. However, it goes without saying that the same effect can be obtained in the widened steel pipe tip receiving method.

[0050]

As described above, according to the present invention,
Prior to tunnel excavation, in a steel pipe precasting method and a steel pipe preloading method for reinforcing a ground by injecting a hardening agent through the steel pipe and the inside of the steel pipe, a plurality of steel pipes are provided at the top of the tunnel. Since a continuous arched hardened body is formed with a hardened region formed around each steel pipe, reinforcement of the ground is achieved by using a steel pipe having a smaller diameter as compared with the conventional one by the wedge arch effect in the arched hardened body. Is reliably achieved. Furthermore, the use of a curing agent containing a fibrous material makes such reinforcement more reliable. Then, by connecting the resin pipe to the rear end of the steel pipe, it becomes possible to omit the extra digging.

As described above, in the excavation of the tunnel, the workability can be improved, the construction period can be shortened, and the material cost and the construction cost can be reduced. Therefore, the present invention is widely suitable for the field of pre-installation work of the steel pipe of the tunnel.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a steel pipe and a resin pipe used in a non-widened steel pipe tip receiving method according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view illustrating excavation of a tunnel by a non-widening steel pipe tip receiving method.

FIG. 3 is an enlarged longitudinal sectional view of a main part after a steel pipe is inserted.

FIG. 4 is a cross-sectional view showing an arrangement state of steel pipes on a cross section of the tunnel.

FIG. 5 is an enlarged vertical cross-sectional view of a main part after a hardener is injected and excavated.

FIG. 6 is a cross-sectional view showing the formation of an arch-like cured body on a cross section of a tunnel.

FIG. 7 is a schematic diagram illustrating a wedge arch effect.

FIG. 8 is a longitudinal sectional view illustrating excavation of a tunnel by a conventional steel pipe tip receiving method.

[Description of Signs] 1 steel pipe 2 resin pipe 6 ground 7 tunnel 8 excavation face 9 excavation area 10 hardening agent 10 'hardening area 11 arched hardened body 12 steel pipe (reinforcing member)

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Claims (9)

[Claims] 1. Prior to excavating a tunnel, a plurality of steel pipes are inserted into the ground from the periphery of the excavation face in a slightly obliquely outward direction, and ground from the rear ends of the steel pipes through the steel pipes. A steel pipe tip receiving method in which a hardener is injected into a mountain, and then the face is dug forward, in which the steel pipe is arranged in a substantially semicircular cross-sectional area along the upper surface of the tunnel, and the arrangement interval is reduced. A hardened region formed around each steel pipe by the hardening agent has a continuous interval with an adjacent hardened region, thereby forming a continuous arched hardened body at the upper portion of the tunnel; Prior construction method. 2. A resin pipe is connected to a rear end of the steel pipe when inserting the steel pipe, a hardening agent is injected from a rear end of the resin pipe, and a part of the resin pipe that protrudes into an excavation area when excavating a face. The method according to claim 1, wherein the steel pipe is pre-received. 3. The tunnel according to claim 1, wherein the plurality of steel pipes are arranged in a staggered manner on a cross section of the tunnel.
The method of receiving steel pipes for tunnels described in 1. 4. A reinforcing member is disposed substantially radially on a cross section of a tunnel at a portion of each of both sides of the tunnel below the both ends of the arched hardened body. 3. The method for receiving a steel pipe tip of a tunnel according to any one of 3. 5. The method according to claim 1, wherein the curing agent contains a fibrous material. 6. A plurality of steel pipes are inserted into the ground from the periphery of the excavation face slightly forward and obliquely outward, and a hardening agent is injected into the ground through the steel pipes from the rear ends of these steel pipes, Thereafter, the structure of the tunnel is formed by a steel pipe tip receiving method in which the face is dug forward, wherein the steel pipe is disposed in a substantially semicircular cross section along the top surface of the tunnel, and The steel pipe is characterized in that a hardened area formed around each steel pipe by the hardener is a continuous space with an adjacent hardened area, and a continuous arched hardened body is formed at the upper part of the tunnel. Tunnel structure by pre-construction method. 7. The tunnel structure according to claim 6, wherein the plurality of steel pipes are arranged in a staggered manner on the cross section of the tunnel. 8. A reinforcing member is disposed substantially radially on a cross section of the tunnel at portions of both sides of the tunnel that extend below both ends of the arched hardened body. A tunnel structure according to the steel pipe tip receiving method according to claim 7. 9. The tunnel structure according to claim 6, wherein the hardening agent contains a fibrous material.