JP2566522B2 - Ground improvement method for tunnel excavation and its surroundings - Google Patents

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, such as unconsolidated soft ground, the tunnel cross section and the ground around the tunnel are usually solidified by chemical injection prior to tunnel excavation. It is tied up and strengthened so that the main fence and the face part do not collapse during tunnel excavation.

[0003] In tunnel boring is to支保the Anakabe the newly generated by excavation in parallel simultaneously with drilling of the tunnels, and securing the cavity space.

Conventionally, such a chemical solution injecting work and a supporting work are performed by individual works, but these works require a great deal of manpower and time, which causes the extension of the work period and the rise of the work cost. .

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

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

[0007]

The present invention is a construction method for improving the ground of a tunnel excavated portion and its peripheral portion from the inside of a tunnel previously excavated so as to be substantially parallel to the tunnel near the tunnel to be excavated. There is a double pipe rod in the ground around the tunnel beyond the cross section of the tunnel to be excavated from the above-mentioned tunnel, and the drilling water ejected from the upper end opening of the rod.
And drilling due to the guide, the bubbler from the upper end opening of the rod
Penetrating repeating a liquid injector according to A, B2 solution that, after penetration has reached a predetermined depth, penetrated only in the state in which kept the double tube rod penetration position or the inner tube, until more deeply After that, the outer pipe is pulled out to the vicinity of the mouth seal box, the fixing material is injected and filled in the space around the outer peripheral surface of the outer pipe, and the integration of the inner pipe and the ground is measured through the fixing material. This relates to the ground improvement method for the tunnel excavation area and its surrounding areas.

[0008]

An embodiment of the method of the present invention will be described below 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 independence,
Preferably, below the midpoint of the lower side thereof, a tunnel 3 extending in the longitudinal direction in parallel with the tunnel is excavated.

[0010] pilot tunnel 3 is utilized as a working pit when performing the ground improvement of tunnel excavation, and a normal 2~5m about caliber. The excavation formation state of the tunnel 3 is shown in FIG. 2. For example, the tunnel 5 can be excavated and formed between the vertical shafts 6 by sequentially adding the segments 5 as the shield type excavator 4 advances.

FIG. 3 shows the situation after the guide shaft 3 is used as a working shaft and the ground is improved according to the method of the present invention. 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 entire area in the tunnel cross-section direction and the tunnel length direction. It is formed.

The formation condition 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 by means of a double pipe rod composed of inner and outer double pipes 7 and 8. The double pipe rods 7 and 8 are inside the tunnel 3 (see FIG. 3). From the tip through the mouth water stop box 9 into the ground 1, the inner pipe 7 and the passages between the inner and outer pipes 7 and 8 from the tip of the water. During this drilling operation, the muddy water generated by the drilling passes through the outside of the outer pipe 8 and is discharged to an appropriate place in the guide shaft 3 through the opening / closing valve 10 provided in the water shut-off box 9.
The forward path and the backward path of the drilling water may be opposite to the above.

The drilling is performed while connecting the inner and outer pipes 7 and 8 in the guide hole 3, and the first drilling is finished at a place slightly inside the virtual tunnel 2 as shown in FIG. 3, for example.

After completion of the first drilling, as shown in FIG. 5, the first step chemical solution injection with the A and B2 solutions is performed through the inner and outer pipes 7 and 8 in accordance with the ordinary method, whereby the inner ，
One ground consolidation part a ₁ formed by the A and B2 liquids is formed in the region in front of the tips of the outer pipes 7 and 8.

[0016] After forming the ground consolidated portion a ₁ of the first step, so as to extend through the central portion of the solid formation portion a ₁ as shown in FIG. 6, for the second time in the manner shown in FIG. 4 drilling is carried out, the liquid injector according to a, B2 liquid in the second step is performed in the manner shown in FIG. 5 After that, as shown in FIG. 7, the front side of the ground consolidated portion a ₁ of the first step, which Second coupled to
The ground consolidation portion a _{2 of the} step is formed.

Hereinafter, by repeating the drilling and the chemical solution injection as described above, the ground consolidation portions a ₁ and a ₁ are formed in the direction crossing the tunnel.
₂ …… are sequentially coupled, and the formation of the ground consolidation part is shown in Fig. 8.
The final consolidated unit a _n as shown in is finished when it reaches the deepest 1A1 (pilot tunnel side have viewed) of the surrounding ground portion 1A At a third FIG.

After the formation of the ground consolidating parts a _{1 to} a _{n to} a predetermined depth is completed, as shown in FIG. 8, the inner pipe 7 is left with the outer pipe 8 left in place. , Further penetrates deep into the ground under the guidance of the drilling water ejected from the tip of the pipe 7. The muddy water generated during the penetration of the inner pipe 7 passes through the outside of the outer pipe 8 through the opening / closing valve 10 of the water shut-off box 9 as in the case of FIG. . The penetration of the inner pipe 7 alone may be omitted.

After completing the penetration of the inner pipe 7 to a predetermined depth as shown in FIG. 8, as shown in FIG. 9, after pulling the outer pipe 8 close to the water stop box 9 at the mouth or withdrawing it,
As shown in FIG. 10, the fixing material 12 (for example, cement milk) is injected and filled into the outer circumferential space 11 of the inner tube 7. The fixing material 12 is injected and filled from the tip through the inner tube 7, for example, but may be injected from the on-off valve 10 in some cases.

By going through the respective steps shown in FIGS. 4 to 10, one cycle of the ground improvement step is completed, and one ground improvement part a is obtained as shown in FIG.

Thus, one cycle of such ground improvement process is repeated at an appropriate pitch in the tunnel cross-section direction and the tunnel length direction, and is continued in both directions, whereby the tunnel cross-section direction and the tunnel length direction are The whole area in the direction can be improved.

In the construction method of the present invention, the ground improvement portion a is ground solidified portions a ₁ , a ₂ ...
It is composed of a _n and an inner tube 7 which passes through the center of them.

After the ground improvement of the tunnel excavation portion is completed 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.

At this time, a part of the inner pipe 7 is left in a penetrating state in the ground 1A in the peripheral portion of the excavated tunnel and in the ground 1A ^, outside the ground 1A. The remaining inner pipe 7A is fixedly fixed in the ground 1A, 1A ^, because it is integrally connected to the ground 1A, 1A ^, via the fixing material 12.

The inner pipe 7 and, in particular, the remaining inner pipe 7A are made of a high-strength material, for example, a steel pipe, and after excavation of the tunnel, they can function the same as lock bolts in supporting work.

Conventionally, during excavation of a tunnel, generally, in parallel with the excavation of the 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 carried out only after the tunnel excavation.

In the method of the present invention, in consideration of the excavability of the tunnel, the portion of the inner pipe 7 that penetrates the virtual tunnel 2 is made of a general-purpose resin pipe having good excavability, such as a PVC pipe. Appropriate.

The high-strength material is not limited to steel pipes, but other reinforced plastics may be used.

[0029]

According to the construction 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. It is possible to reduce the construction period, and it is possible to reduce the construction period and the construction cost at the same time.

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

[Brief description of drawings]

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

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

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 the first drilling and the penetration of the double pipe rod into the ground in the method of the present invention.

FIG. 5 is an explanatory view schematically showing a chemical liquid injection state of liquids A and B2 in the first step.

FIG. 6 is an explanatory view schematically showing a second drilling and penetration situation.

FIG. 7 is an explanatory view schematically showing a chemical liquid injection state of liquids A and B2 in the second step.

FIG. 8 is an explanatory view showing a hole drilling by a double pipe rod and a hole drilling and penetrating condition by an inner pipe alone, which is continuously performed after the chemical solution is injected.

FIG. 9 is an explanatory view schematically showing the situation of an outer tube drawing process performed subsequent to FIG.

FIG. 10 is an explanatory view schematically showing a situation of a fixing material injecting and filling step performed subsequent to FIG. 9.

[Explanation of symbols]

 1 Ground 2 Virtual tunnel 3 Guide shaft 4 Shield type excavator 5 Segment 6 Vertical shaft 7 Inner tube 8 Outer tube 9 Water stop box 10 Open / close valve 11 Circumference 12 Fixing material

Claims (1)

(57) [Claims] 1. A method for improving the ground of a tunnel excavation portion and its peripheral portion from the inside of a tunnel that has been excavated and formed in the vicinity of the tunnel to be excavated so as to be substantially parallel to the tunnel. A double pipe rod in the ground around the tunnel crossing the cross section of the power tunnel and the upper end of the rod.
And drilling by guiding the drilling water released from the opening, the lock
Penetration while repeating chemical solution injection with A and B2 liquid injected from the upper end opening of the dope , and after the penetration reaches a predetermined depth, with the double pipe rod remaining in the penetration position,
Alternatively, after penetrating only the inner tube further deeply, the outer tube is pulled out to the vicinity of the mouth seal box, and the fixing material is injected and filled into the space around the outer peripheral surface of the outer tube, and the inner tube is inserted through the fixing material. A ground improvement method for a tunnel excavation part and its peripheral part, which is characterized by integration and integration with the ground.