JPH0776819A - Improving method for ground of tunnel excavation part and peripheral part thereof - Google Patents

Abstract

PURPOSE:To perform improvement of the peripheral ground of a tunnel by the less number of man powers and with a short term of works by a method wherein in prior to excavation of a tunnel, injection for a chemical and timber ing based on a lock bolt method are simultaneously executed. CONSTITUTION:A heading 3 is previously excavated and built below a tunnel 2 to be excavated. Outer pipes 11 for injection are driven from the interior of the heading 3 such that the outer pipe is driven over the cross section of the tunnel 2 to be excavated and down to a given depth in the ground of the peripheral part of the tunnel. By using an inner pipe for injecting a double packer introduced in the outer pipe 11 for injection, chemicals are injected in a ground. A high strength part 11A of the outer pipe 11 for injection is caused to remain in a drive position. Simultaneously, by a high strength fixing agent injected in the outer peripheral part of a part 11a for fixing of the high strength part 11A to fill the outer peripheral part with the fixing agent, the part 11a for fixing is fixed in a drive position. By repeating above process, a plurality of ground improved parts (a) are built to the whole of the periphery of the tunnel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement method for a tunnel excavation portion and its peripheral portion.

[0002]

2. Description of the Related Art Conventionally, when constructing a tunnel in soft ground that has low self-sustainability, for example, unconsolidated ground, the tunnel cross section and the ground around it are usually injected with a chemical solution prior to tunnel excavation. It is consolidated and strengthened so that the main shaft and the face part do not collapse during tunnel excavation. In addition, while the tunnel is being dug, a hollow space is secured by supporting the pit wall newly created by the excavation at the same time as the excavation of the tunnel.

Conventionally, such chemical solution injecting work and supporting work have been performed by individual works, but these works require a great deal of manpower and time, which is a cause of extension of the work period and soaring of the work cost. .

Further, although the ground around the pit wall newly formed by tunnel excavation is consolidated and strengthened by the chemical liquid injection, the effect of the ground improvement by the chemical liquid injection is limited, so that the pit wall As a measure to prevent collapse of the mine wall, which is a concern during support work, it is not perfect, and further improvement is desired.

The present invention has been made for the purpose of eliminating such conventional problems.

[0006]

The present invention relates to a method for improving the ground of a tunnel excavated portion and its peripheral portion from the inside of a tunnel formed by excavating it substantially in parallel with a tunnel to be excavated. Using an injection outer pipe built so as to reach a predetermined depth in the ground around the tunnel crossing the cross section of the tunnel to be excavated, and an inner pipe for injection with a double packer introduced into the outer pipe Including the step of injecting the chemical liquid, after the chemical liquid injection, of the outer pipe left at the built-in position, the portion that is inserted and installed in the ground around the tunnel cross section is made up of a high-strength member. In addition, the fixing portion is provided in a portion near the tip side, and the fixing portion is fixed and fixed at the built-in position by a fixing material that is injected and filled around the outer periphery of the fixing portion before or after the chemical solution is injected. Tunnel excavation section and On the ground improvement method of the peripheral portion thereof.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the method of the present invention with reference to the accompanying drawings.

In carrying out the method of the present invention, as shown in FIG. 1, first, in the vicinity of the lower part of the virtual tunnel 2 to be constructed, in the unconsolidated soft ground 1 having low self-sustaining property,
Preferably, below the midpoint of the lower side thereof, a tunnel 3 extending in the longitudinal direction in parallel with the tunnel is excavated.

The guide pit 3 is used as a working pit when performing ground improvement in a tunnel excavation portion, and usually has a diameter of about 2 to 5 m. The excavation formation situation of the tunnel 3 is shown in Fig. 2.
For example, the guide shaft 3 can be excavated and formed between the vertical shafts 6.6 by successively adding the segments 5 as the shield type excavator 4 advances.

FIG. 3 shows a situation after the ground improvement is performed according to the method of the present invention using the guide shaft 3 as a work shaft. Reference numeral a indicates one ground improvement portion formed by applying the method of the present invention. The ground improvement portion a is repeatedly formed in both directions at an appropriate pitch in order to improve the ground in the tunnel cross-section direction and the tunnel length direction. It is formed.

The formation situation of the ground improvement portion a will be described in the order of steps with reference to FIGS.

FIG. 4 shows the situation at the time of forming a hole, and the hole is formed by using the casing tube 7. The casing tube 7 is inserted from the inside of the guide hole 3 through the mouth water stop box 8 into the ground 1 under the guide of drilling water ejected from the tip of the tube 7, and the muddy water generated by the drilling is It passes through the outside of the casing 7 and is discharged to an appropriate place in the tunnel 3 through the opening / closing valve 9 provided in the mouth water-stop box 8. The insertion of the casing tube 7 for forming the hole is continuously performed in the tunnel 3 and reaches a predetermined depth in the ground 1a around the cross section of the virtual tunnel 2 as shown in FIG. 3, for example. It ends when you do.

After the formation of the drilled holes 10, the injection outer pipe 11 is built into the drilled holes 10 as shown in FIG.

The outer pipe 11 for injection is for improving the ground by injecting a chemical solution in cooperation with the inner pipe for injection with a double packer described below, and has a multi-stage structure with an appropriate interval in the direction of the pipe length. Is equipped with a large number of inlets 13 with check valve rings 12 (see FIG. 9). The outer tube 11 for injection used in the method of the present invention has a closed tip as shown in FIG.
A wing-shaped anchor member 14 capable of expanding and contracting against a restoring spring (not shown) is provided at the tip of the closed portion. In addition, a portion 11A of the outer pipe 11 that is inserted and installed in the ground 1a in the peripheral portion that exceeds the tunnel cross section in FIG.
In order to retain the same function as the lock bolt in the lock bolt construction method, is constructed by adding a pipe member made of high strength such as steel or reinforced plastic.

As shown in FIGS. 3 and 9, the high-strength portion 11A of the outer tube 11 is divided into a fixing portion 11a on the distal end side and a general portion 11b functioning as an injection on the proximal end side. A separate packer 15 is provided on the outer peripheral surface side of the boundary between 11a and the general portion 11b, and in the packer 15, one injection port 13a with a check valve ring 12a is opened.

A partition 16 is provided between the fixing portion 11a and the general portion 11b so as to isolate the inner space, and an injection passage 17 penetrating in the axial direction of the pipe is formed in the partition 16. . The injection passage 17 may be provided with a check valve 18.

The fixing portion 11a is not always the injection outer tube 11
It is not necessary to utilize a part of the lock bolt 28, for example, as shown in FIG.
You may make it comprise using.

The outer pipe 11 having the above-mentioned structure is inserted into the casing tube 7 from the proximal end side to the distal end while being sequentially added from the distal end side in the tunnel 3 (see FIG. 3), and the During the passage, the anchor member 14 is restrained by the inner wall of the tube and maintains the contracted state against the restoring spring, and when passing through the tip of the casing tube 7 as shown in FIG. 5, the anchor member 14 is released from the restraint of the inner wall of the tube and restored. The spring function automatically restores the expanded state, and the hole wall 10a of the drilled hole 10
The outer pipe 11 is restrained at the installed position. The separating packer 15 is kept in the contracted state while the outer tube 11 is being built. After the outer pipe 11 has been built, the casing tube 7 is drilled as shown in FIG.
The injection inner pipe 20 having the double packers 19 and 19 is inserted into the outer injection pipe 11 while being replenished in the guide hole 3 while being pulled out to the vicinity of the mouth of No. 0. The double packers 19, 19 are first placed at the position of the separating packer 15, and the liquid agent is supplied from the injection port (not shown) opened between the packers 19, 19 through the injection port 13a with the check valve ring 12a. It is injected and filled in. Therefore, the packer 15 expands, as shown in FIG.
A is distinguished from the second filling portion 10B on the proximal end side.

After the sectioning of the drilled hole 10 by the expansion of the packer portion 15 is completed, the opening / closing valve 9 is closed with the gap between the casing tube 7 and the outer tube 11 closed by the plug 21.
A seal grout is injected and filled into the second filling portion 10B through the through hole as indicated by the arrow 22. The filling and filling of the seal grout may be performed using the filling inner tube 20.

As shown in FIG. 7, after the seal grout 23 filled in the second filling section 10B is solidified, the injection inner pipe 20 is stepped down from the insertion position shown in FIG. 7 toward the tunnel 3. Double packers 19 and 19 and outer tube for injection 1
The chemical solution is injected in a conventional manner while aligning the check valve ring 12 with the injection port 13 of each stage of No. 1 and thereby the surrounding ground is solidified.

After the injection of the chemical solution is completed, as shown in FIGS. 8 and 9, an injection pipe 24 is inserted into the outer pipe 11 in place of the injection inner pipe 20, and its tip is provided with a partition 16 as shown in FIG. It is connected to the injection passage 17. In this state, from the injection pipe 24, the injection passage 17, the inside of the fixing portion 11a and the injection opening 13b with the check valve ring 12b in the peripheral portion thereof are sequentially passed to the first filling portion 10A.
A high-strength fixing material 25 such as cement milk is injected and filled therein.

After the injection and filling of the high-strength fixing material 25 into the first filling portion A is completed, the injection pipe 24 is pulled out into the guide hole 3 and is recovered, or the injection pipe 24 is not recovered. It is fixedly fixed in the outer tube 11 via a fixing material (not shown) injected and filled in the peripheral space 26 (see FIG. 9). In the latter case, it is advantageous to use a hollow rock bolt as the injection pipe 24 as shown in FIG. 9 in order to strengthen the outer pipe 11. In this case, the injection pipe 24 and the outer pipe 11 are preferably made of plastic (including reinforced plastic) in consideration of future excavation work.

By sequentially passing through the steps of FIGS. 4 to 8, one cycle of the ground improvement step is completed, and as shown in FIG.
Two ground improvement parts a are obtained.

By repeating one cycle of the ground improvement process as described above at a proper pitch in the tunnel cross-section direction and the tunnel length direction, and continuously in both directions,
The ground can be improved in the entire tunnel cross-section direction and tunnel length direction.

Ground improvement portion a obtained by the method of the present invention
It includes a consolidated ground portion a ₁ reinforced with liquid injector shown in FIG. 3, the outer tube 1 to penetrate the center of the solid forming the ground part a ₁
Including 1 and.

The high-strength portion 11A of the outer tube 11 (see FIG. 3)
(See) is the ground 1 around the tunnel after excavation.
This is the part that remains in a.

The high-strength portion 11A of the outer tube 11 is divided into a general portion 11b necessary for injecting a chemical solution into the ground 1a in the peripheral portion and a fixing portion 11a, and the fixing portion 11a has a high strength filled in the periphery thereof. It is firmly fixed and fixed at the built-in position by the fixing material 25.

After the tunnel is excavated, the high-strength portion 11A of the outer pipe 11 which remains in the ground 1a around the tunnel excavates the high strength,
By firmly fixing and fixing the fixing portion 11a, it becomes possible to perform the same function as the lock bolt in the lock bolt method well known as one of the supporting works.

Therefore, in the method of the present invention, the chemical solution injecting process and the supporting work in the rock bolt process can be performed at the same time.

After finishing the ground improvement of the tunnel excavation portion according to the method of the present invention, the portion of the virtual tunnel 2 shown in FIG. 3 is excavated according to the ordinary method.

Considering the excavability during tunnel excavation, the outer pipe 1
1 (If the injection tube 24 is left, the injection tube 24
It is preferable to use a material such as plastic that is easy to excavate for the portion penetrating the area of the virtual tunnel 2 (including the above).

Conventionally, during excavation of a tunnel, in parallel with the excavation of a tunnel, support work is carried out in order to prevent collapse of a new pit wall caused by excavation. Since the support work has already been completed, new support work can be omitted or at least simplified. Further, since the support work precedes the tunnel excavation, the work safety can be improved as compared with the case where the support work is performed for the first time after the tunnel excavation.

FIG. 11 shows another embodiment of the method of the present invention. In this embodiment, the double packers 30 and 30 provided in the inner pipe 29 for injection are the first and second lines 3.
Expansion by pressurized fluid that is individually supplied and discharged from 1, 32,
The packer 30 is contractible, and the upper end of the high-strength fixing material supply line 33 is opened at the upper end of the upper packer 30 as an inlet.

The upper packer 30 can also serve as the partition 16 in the embodiment shown in FIG. 9, and therefore the partition 16 is not provided in this embodiment.

FIG. 11 corresponds to FIG. 9 in the previous embodiment, and the steps until the outer pipe 11 is installed are substantially the same as those in the previous embodiment.

In this embodiment, after the outer pipe 11 has been built, the inner pipe 29 is placed inside the outer pipe 11 by the double packer 3.
0 and 30 are inserted in a contracted state, and after being aligned with the separate packer 15, the double packer 30 and 30
Are inflated to form a seal. Then, the fluid is pressurized and filled into the separate packer 15 through the inner pipe 29, and as a result, the packer 15 expands to separate the first filling portion 10A and the second filling portion 10B.

Next, the high-strength fixing material 34 is supplied to the supply line 33.
Injecting port 1 with check valve ring 12B from inside fixing section 11a through
It is injected and filled into the first filling portion 10A via 3b. In this case, as the fixing material 34, a reaction hardening type cemented cement material having a relatively short gel time can be used. Before the filling and filling operation of the fixing material 34 into the first filling portion 10A, the filling and curing and solidification of the seal grout 23 into the second filling portion 10B can be completed.

After the filling and the curing and solidification of the fixing material 34 into the first filling portion 10A are completed, the double packers 30 and 3 are provided.
0 is deflated, and it is inflated again at the position lowered by one step, and the chemical solution is injected in the usual manner. Below, double packer 3
By repeating the contraction and expansion of 0 and 30 and the step-down and injecting the chemical solution, it is possible to obtain the ground improvement part a including the outer pipe 11 as a core, as in the previous embodiment.

This embodiment is substantially the same as the previous embodiment except that the chemical solution is injected after the high-strength fixing material 34 is injected and filled into the first filling portion 10A.

In the method of the present invention, the formation position of the tunnel 3 is
In addition to the lower vicinity of the virtual tunnel 2 shown in FIG.
As shown in 14, it may be inside the virtual tunnel 2.

[0041]

According to the method of the present invention, prior to excavation of a tunnel, a chemical solution injection work and a support work based on the rock bolt construction method can be performed at the same time. The time can be reduced, and the construction period and the construction cost can be reduced at the same time.

Further, since the supporting work is carried out prior to the excavation of the tunnel, the work stability can be improved as compared with the case where the supporting work is carried out for the first time after the tunnel excavation.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing the formation position of a tunnel in the method of the present invention.

FIG. 2 is an explanatory view schematically showing a state of formation of the tunnel.

FIG. 3 is an overall view schematically showing a ground improvement situation in the method of the present invention.

FIG. 4 is an explanatory view schematically showing a drilling situation in the method of the present invention.

FIG. 5 is an explanatory view schematically showing a situation in which the outer pipe is being built.

FIG. 6 is an explanatory view schematically showing a state where the separate packer is inflated after the outer pipe is installed.

FIG. 7 is an explanatory view schematically showing a situation where a chemical solution is being injected after filling the seal grout.

FIG. 8 is an explanatory view schematically showing a situation at the time of filling with the high-strength fixing material.

FIG. 9 is an enlarged detailed view of the same.

FIG. 10 is a diagram corresponding to FIG. 9 showing a modified example of the fixing unit.

FIG. 11 is a view corresponding to FIG. 9 and shows an example of another embodiment of the method of the present invention.

FIG. 12 shows an example of changing the guide hole forming position in the method of the present invention.

FIG. 13 is a diagram showing still another modification.

FIG. 14 is a diagram showing still another modification.

[Explanation of symbols]

 1 Soft Ground 2 Virtual Tunnel 3 Tunnel 4 Shield Type Excavator 5 Segment 6 Vertical 7 Casing Tube 8 Water Stop Box 9 Opening / closing Valve 10 Drilling Hole 11 Outer Pipe for Injection 12 Check Valve Ring 13 Injection Port 14 Anchor 15 Separate Packer 16 Partition 17 Injection passage 18 Check valve 19 Double packer 20 Inner pipe for injection 21 Plug 22 Arrow 23 Seal grout 24 Injection pipe 25 High-strength fixing material

Claims (1)

[Claims] 1. A method for improving the ground of a tunnel excavated portion and its peripheral portion from the inside of a tunnel formed by excavating it substantially parallel to the tunnel to be excavated. An injection outer tube built so as to reach a predetermined depth in the ground of the periphery beyond it, and a step of injecting a chemical solution by using an injection inner tube with a double packer introduced into the outer tube, Of the above-mentioned outer pipe left at the built-in position after injection of the chemical liquid, the portion which is inserted and installed in the ground around the tunnel crossing the tunnel cross section is composed of a high-strength member and is located near the tip side. A tunnel excavation characterized in that a fixing portion is provided in a part thereof, and the fixing portion is fixed and fixed at a built-in position by a fixing material injected around the outer periphery of the fixing portion before or after the chemical solution is injected. Improvement work in and around the section .