JPH06100079B2 - Tunnel excavation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a method for excavating a tunnel in an unconsolidated mountain where a soil cover is shallow.

(Prior Art) As the area of application of the mountain tunnel method (NATN method) expands, the number of cases where it is constructed in urban areas with low natural strength is increasing.

In this case, because the stability of the face is low, the tunnel is divided into small parts, and various auxiliary construction methods are used to suppress the influence on the ground structure, that is, the subsidence.

A technique conventionally used as this auxiliary method is a fore piling method.

This method is a method in which a reinforcing rod, a rock bolt, or a single pipe having a length of about 2 to 3 m is drilled at an appropriate interval at an angle of 10 to 30 ° from the face and driven. If necessary, a ground reinforcement injection method may be used in combination.

(Problems to be Solved by the Invention) In the conventional fore piling method, since there is no continuity in the tunnel crossing direction, the effect is small particularly in a ground with low tackiness or an extremely weak ground.

In addition, the injection type has a problem in terms of permeability of the injection material and safety.

The present invention has been proposed in view of the above problems of the prior art, and an object thereof is to provide a tunnel excavation method in which ground subsidence is suppressed during tunnel excavation and the stability of the face is improved. In point.

(Means for Solving the Problems) In order to achieve the above object, according to the tunnel excavation method of the present invention, in the vicinity of the arch portion of the tunnel in the face of the face, an earth auger is provided in the tunnel transverse direction and the longitudinal direction. After excavating a slit extending over the concrete arch shell of the preceding concrete, while pulling out the earth auger from the slit, a quick-hardening concrete is placed in the slit, and the following steps are performed around the tunnel arch part. After that, pre-lining is performed around the arch part of the tunnel with thin-walled concrete arch shells extending continuously in the transverse direction and longitudinal direction of the tunnel, and then the face is excavated.

(Operation) According to the present invention, as described above, the slit extending around both the tunnel transverse direction and the tunnel longitudinal direction is superposed on the preceding concrete arch shell by the earth auger around the arch portion of the tunnel in the face. After excavating, while retreating the earth auger from the slit, place a quick-hardening concrete in the slit, and repeat the following steps in the tunnel arch area,
A concrete arch shell lining is used to reinforce the ground in front of the tunnel, suppress subsidence due to excavation of the tunnel, and improve the stability of the face.

(Examples) The present invention will be described below with reference to illustrated examples.

(A) is an excavator arranged in a tunnel hole (B), and is a boom mounted on a vehicle body (2) mounted on a traveling crawler (1) so as to be rotatable and vertically rotatable. (3)
, A plurality of ground augers (4) parallel to each other are movably supported on the ground auger support member (4a) (see FIG. 1), and the hollow rotary shaft of each ground auger (4) has concrete The delivery pipe (5) is connected, and concrete is poured from a nozzle provided at the tip of the rotary shaft.

The earth auger (4) is attached to, for example, an endless belt that is bridged between a driving wheel and a driven wheel that are mounted on both ends of the earth auger support member (4a), and the earth auger (4) must circulate and move. The earth auger (4) is configured to be moved back and forth.

Then, the earth auger (4) is driven and rotated, and is advanced along the earth auger guide member (4a), so that the front end portion of the preceding concrete arch shell (D) in the longitudinal direction is superposed and continuous with the cutting face. A slit (6) is excavated in the front ground (see Fig. 2), and when the excavation is completed, the earth auger (4) is retracted and pulled out from the slit (6), while the fast-setting concrete (7) is attached to the slit (6). ) Is injected (see FIG. 2). In the figure, (C) is a concrete supply vehicle.

Then, the boom (3) is tilted in a swinging manner and the above steps are sequentially performed around the arch portion of the tunnel, and the preceding concrete arch is extended around the arch portion in the transverse direction and the longitudinal direction of the tunnel. A thin concrete arch shell (D) in which the above-mentioned concrete is poured and filled into the slit is continuously provided by being superposed on the shell (D).

FIG. 7 shows the order of construction of this concrete arch shell (D). One end of the shell portion (d '), which is to be installed in the middle, is adjacent to the adjacent shell portions (d) that have been installed at predetermined intervals. They are constructed so that they overlap each other (see FIG. 8).

Thus, around the arch portion of the tunnel at the face, the trailing end portion is partially overlapped with the lower end portion of the leading end of the preceding thin-walled concrete arch shell (D) continuously extending in the transverse and longitudinal directions of the tunnel. After constructing the playlining with a thin concrete arch shell (D), excavation for one span of the face is performed.

This excavation is mainly mechanical excavation using a backhoe (E), but the upper half side wall is partially excavated by human power. In addition, steel supports are installed inside the pre-lining, but since the pre-lining is inclined in the tunnel axis direction, two types of steel supports (8a) and (8b) with different curvatures alternate. Be built. After that, sprayed concrete (9) is coated. At this time, the sprayed concrete (9) is applied up to the inner edge of the supporting work due to the waterproof sheet (see FIG. 3).

Next, as shown in FIG. 4, excavation for one span is further carried out, and thereafter, prelining of the next span is performed in the same manner as described above (see FIG. 5).

Hereinafter, the above steps are repeated to excavate a tunnel.

9 and 10 show the guide support work of the earth auger (4) in the excavator (A), and the arch-shaped guide member (10) supporting the earth auger support member (4a) is a tunnel hole. The guide member (10) is movably mounted on a bracket (11) arranged in the lower part of both sidewalls along the tunnel axis direction, and the guide member (10) moves in the tunnel axis direction as the excavation progresses, and the member ( The earth auger support member (4a) is configured to move along 10).

As described above, according to the method shown in the illustrated embodiment, the play lining is constructed by the thin concrete arch shell (D) that is continuous around the tunnel arch portion in the tunnel crossing direction and the longitudinal direction. Subsidence of the ground surface due to tunnel excavation is suppressed, the stability of the face is improved, and tunnel excavation is performed safely and reliably.

Further, in the excavator (A), a plurality of ground augers (4) mounted on the excavator (A) are parallel to each other and the face is excavated smoothly, so that stress concentration is small and supporting work is reduced.

Furthermore, depending on the method of using the excavator (A), tunnel construction with an arbitrary cross section becomes possible.

As shown in FIG. 6, both side wall portions of the tunnel except for the play lining construction area around the tonel arch portion constructed by this method are subjected to primary lining with shotcrete (F).

(Effects of the Invention) According to the present invention, as described above, a slit extending over the tunnel transverse direction and the longitudinal direction is superposed on the preceding concrete arch shell by an earth auger around the arch portion of the tunnel in the face. After machining, while pulling out the earth auger from the slit, place a quick-hardening concrete in the slit and repeat the above process to continuously extend the thin wall concrete in the tunnel crossing direction and the longitudinal direction. By constructing the play lining consisting of arch shells, the shells will be used to reinforce the ground in front of the face, and to prevent subsidence of the ground surface due to tunnel excavation, and to excavate the tunnel safely and reliably in this state. It is a thing. In particular, since the quick-hardening concrete is immediately filled after the slit cutting, the rock-opening time after excavation is short, and the triaxial state of the tunnel circumferential direction and the tunnel axis direction is continued, so that Small displacement,
The surface subsidence suppression effect is exhibited.

In addition, the tunnel excavation work is carried out in the thin-walled concrete arch shell that overlaps and extends in the transverse and longitudinal directions of the tunnel arch part that was previously constructed, so the stability of the face is high and the stability is secured. To be done.

Furthermore, by improving the stability of the face like this,
It enables tunnel excavation of large cross section, shortening the construction period,
Construction costs are reduced.

[Brief description of drawings]

1 to 5 are vertical side views showing steps of an embodiment of a tunnel excavation method according to the present invention, FIG. 6 is a vertical front view of FIG. 1, and FIG. 7 is construction of a thin concrete arch shell. Fig. 8 is an explanatory view showing the order, Fig. 8 is a detailed view of the part VIII in Fig. 7, Fig. 9 is a vertical sectional side view showing the guide support work of the earth auger support member of the excavator, and Fig. 10 is a vertical sectional front view thereof. is there. (A) ... Excavator, (D) ... Concrete arch shell, (4) ... Earth auger, (6) ... Slit,
(7) …… Concrete.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hirokazu Kami 4-6-15 Sendagaya, Shibuya-ku, Tokyo Within Fujita Industry Co., Ltd. (72) Yoichi Mimura 4-6-115 Sendagaya, Shibuya-ku, Tokyo Fujita Industry Co., Ltd. Examiner Junji Yuda (56) Reference JP-A-60-19897 (JP, A) JP-A-58-110797 (JP, A) JP-A-56-9595 (JP, A)

Claims (1)

[Claims] 1. Around the arch part of the tunnel in the face,
With the earth auger, the slit extending in the tunnel crossing direction and the longitudinal direction is superposed on the preceding concrete arch shell and excavated. The following steps are sequentially performed around the arch part of the tunnel.
A tunnel excavation method characterized by excavating a face after performing pre-lining with thin-walled concrete arch shells that extend continuously across the tunnel and in the longitudinal direction.