JP2022118274A - tunnel excavation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tunnel excavation method capable of, when directly cutting an earth retaining wall of a starting port part formed of reinforced concrete by excavation means of a shield machine. preventing a back-filling material supply passage provided in a skin plate outer wall of the shield machine from being an obstacle when the shield machine passes through the earth retaining wall.

SOLUTION: In a reinforced concrete earth retaining wall W1, after drilling the range of a back-filling material supply passage 14 butting on a shield machine 1 when starting, the earth retaining wall W1 is cut by a cutter disk 2, and the shield machine is allowed to intrude into the natural ground for drilling sediment. When drilling the range where the back-filling material supply passage 14 butts on the shield machine 1 when starting, an infilling material is injected into a hole H formed by drilling the earth retaining wall W1.

SELECTED DRAWING: Figure 11

COPYRIGHT: (C)2022,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a tunnel excavation method, and more particularly to a method for excavating a starting opening in a starting shaft in tunnel excavating work using a shield machine.

In the shield tunneling method for constructing a tunnel in the ground, a shield tunneling machine is assembled in a starting shaft and started to excavate the ground. After reaching the arrival shaft, the shield machine is disassembled in the arrival shaft and carried out to the ground.

The earth retaining walls of the starting and arriving shafts in the shield tunneling method must withstand the earth pressure and water pressure at the depth of the shaft. Steel sheet piles and the like are used as such earth retaining walls, and some are reinforced with steel shoring.

Here, the earth retaining wall including the starting mouth portion is formed of sheet piles, and immediately before the shield machine starts to move, the sheet pile in front of the cutter board is cut along the outer diameter of the shield machine to form the starting mouth. is known. In this case, before cutting the sheet pile, a solidification agent is injected into the earth and sand of the natural ground in front of the cutter board to improve the ground and prevent the inflow of groundwater and earth and sand into the shaft.

Such techniques require time-consuming operations such as injection of solidifying material and assembly and dismantling of shoring.

Therefore, the earth retaining wall at the starting point was constructed from concrete with high-strength reinforcing material that can be cut by the cutter board of the shield machine, and the earth retaining wall was directly cut by the shield machine. There is a technology that This technology eliminates the need for ground improvement and shoring removal work when the train is launched, making it possible to shorten the construction period and reduce costs.

Now, in the shield construction method, the shield machine moves forward while leaving the ring-shaped segment, so the segment is exposed from the rear end of the shield machine. In addition, since the segments are assembled inside the shield machine, the outer diameter of the segments is smaller than the inner diameter of the shield machine, and as a result, a gap is formed between the cut ground and the segments. Therefore, it is necessary to fill this gap by pouring back-filling material from the vicinity of the rear end of the shield machine.

One of the techniques for filling the gap in the shield construction method is the simultaneous backfill injection method. In this method, a plurality of back-filling injection devices are provided on the outer peripheral surface of the upper rear portion of the shield machine, and the back-filling material is injected as the shield machine advances.

Regarding the shield tunneling machine that uses both the technology of directly cutting the earth retaining wall at the starting port portion with the shield tunneling machine and the technology of simultaneously injecting the backfilling material, Patent Document 1 (Japanese Patent Application Laid-Open No. 09-100696) and Patent Document 2. (Japanese Unexamined Patent Application Publication No. 10-037679) is known.

Patent Literature 1 describes a technique in which a plurality of cutter bits are provided in front of a back-filling injector, and the height of the bits increases toward the rear. Further, Patent Document 2 describes a technique for over-digging when excavating a retaining wall or in the ground by providing a rotating cutter on the side surface of the shield machine in front of the backfilling injector so that it can be retracted.

JP-A-09-100696 JP-A-10-037679

Now, the backfilling material supply path for supplying the backfilling material to the backfilling injection device is provided so as to protrude from the outer wall of the skin plate that constitutes the shield machine. That is, the back-filling material supply path is a projecting portion provided outside the cutting range of the cutter board (excavating means).

As described above, in the construction method using fiber-reinforced concrete as an earth retaining wall, the earth retaining wall is directly cut by a shield machine. At this time, in the shield machine using the simultaneous backfilling injection method, the backfilling material supply path, which is a protruding portion, protrudes outside the cutting range of the cutter board.

Such a problem applies not only to the back-filling material supply path, but also to various protrusions protruding from the outer wall of the skin plate.

The present invention has been made in view of the above-mentioned technical background. To provide a tunnel excavation method capable of avoiding a protrusion provided on an outer wall of a skin plate of a machine from becoming an obstacle when passing through an earth retaining wall.

In order to solve the above problems, the tunnel excavation method of the present invention as set forth in claim 1 provides soil made of concrete in which reinforcing materials are arranged and which can be cut by rotary excavation means installed at the tip of a shield machine. A construction step of constructing a retaining wall at a starting opening portion of a starting shaft; a drilling step of cutting the reinforcing material closest to the ground in the retaining wall and drilling to a position that does not reach the ground; and an excavating step of entering and excavating the earth retaining wall, and in the drilling step, a filling material is injected into a hole formed by drilling the earth retaining wall.

According to a second aspect of the present invention, there is provided a tunnel excavation method according to the first aspect of the invention, wherein the filling material is a water stopping filling material.

The tunnel excavation method of the present invention according to claim 3 is the tunnel excavation method according to the invention according to claim 1 or 2, wherein the projecting portion is located forward in the traveling direction of the shield machine in the excavation step. It is characterized in that a protective bit is installed for excavating the range that hits the retaining wall.

The tunnel excavation method of the present invention according to claim 4 is the tunnel excavation method according to claim 3, wherein the protection bit is covered with a covering material that can be crushed by the earth retaining wall prior to the excavation step. Characterized by

The tunnel excavation method of the present invention according to claim 5 is the tunnel excavation method according to any one of claims 1 to 4, wherein the protruding portion extends in the axial direction of the outer wall of the skin plate of the shield machine. a back-filling material supply path provided along the skin plate for supplying the back-filling material to the gap between the excavation hole behind the skin plate and the segment installed in the excavation hole.

According to the present invention, for a concrete earth retaining wall reinforced with reinforcing material, after drilling a range in which the projecting portion provided on the outer wall of the skin plate hits when the shield machine starts moving, earth retaining means is used to excavate the earth retaining wall. The earth and sand are excavated by cutting the wall to enter the natural ground and excavate the earth and sand. Since the filling material is injected into the hole, it is possible to prevent the projecting portion from becoming an obstacle when passing through the retaining wall.

FIG. 2 is a configuration diagram of the inside of the shield machine of the present embodiment seen through from the side; FIG. 2 is a front view of a cutter head of the shield machine of FIG. 1; FIG. 2 is an explanatory view showing a backfilling material supply path and protection bits provided in the shield machine of FIG. 1 extracted from a radial cross section of a skin plate; FIG. 4 is a plan view showing one back-filling material supply path and a protection bit; FIG. 5 is a cross-sectional view taken along line AA of FIG. 4; FIG. 4 is an explanatory diagram showing the positional relationship between a backfilling material supply path and a protection bit; FIG. 4 is a side view showing a main part of the starting shaft in the tunnel excavation method of the present embodiment; FIG. 8 is an explanatory diagram showing an earth retaining wall constructed at the starting port portion of the starting shaft in FIG. 7 ; FIG. 9 is a cross-sectional view taken along line BB of FIG. 8; FIG. 5 is an explanatory diagram showing the positional relationship between the holes and the back-filling material supply path in the drilling process; It is explanatory drawing which looked at the working state in the drilling process from the side of the shield machine. It is explanatory drawing which looked at the working state in the drilling process from the plane of the shield machine.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment as an example of the present invention will be described in detail below with reference to the drawings. In the drawings for describing the embodiments, in principle, the same components are denoted by the same reference numerals, and repeated description thereof will be omitted.

First, the configuration of the shield machine used in the tunnel excavation method of the present embodiment will be described with reference to FIGS. 1 and 2. FIG. Here, FIG. 1 is a configuration diagram of the inside of the shield machine of the present embodiment seen through from the side, and FIG. 2 is a front view of the cutter head of the shield machine of FIG.

In these drawings, the shield excavator 1 of the present embodiment has a cutter board (excavating means) 2 pressed against a face (excavation surface) and rotated to excavate the natural ground. Mud is pumped through a mud pipe 5 to a mud chamber 4 provided in the skin plate 3, and the mud pressure in the mud chamber 4 is adjusted to match the earth pressure of the face and the groundwater pressure to stabilize the face. This is a slurry type shield tunneling machine that forms a tunnel in the natural ground while discharging slurry accumulated in a chamber 4 to the outside of the tunnel through a slurry discharge pipe 6. - 特許庁

The cutter board 2 constituting the shield machine 1 is an excavating member having a circular front surface for excavating the face of the natural ground. installed in the state.

In this embodiment, the cutter board 2 is of the face plate type, and as shown in FIG. main spokes 2-2, retractable spokes 2-3 positioned between the main spokes 2-2 and slidable in the longitudinal direction, and gaps between the main spokes 2-2 and the retractable spokes 2-3. and an outer peripheral ring portion 2-5 connecting the tip portions of the main spokes 2-2 and the retractable spokes 2-3. The hub portion 2-1, the main spokes 2-2 and the face plate portion 2-4 are integrally formed with each other.

The front surfaces (surfaces facing the face) of the hub portion 2-1, main spokes 2-2, retractable spokes 2-3, face plate portion 2-4 and outer ring portion 2-5 of the cutter board 2 are covered with cobbles, etc. Equipped with a plurality of bits 2a and scraper teeth 2b for crushing and excavating the ground, and an earth and sand inlet 2-6 for taking earth and sand excavated by the rotation of the cutter board 2 into the mud chamber 4. is formed. A copy cutter 2c is attached to the outer peripheral surface of the cutter board 2 for overcutting during construction of a sharp curve and controlling the attitude of the shield machine 1, for example.

The skin plate 3 positioned behind the cutter board 2 is composed of a front body plate 3a and a rear body plate 3b formed of, for example, cylindrical steel plates. The front body plate 3a and the rear body plate 3b are engaged in such a manner that the spherical bearing portion on the front end side of the rear body plate 3b enters in contact with the inner peripheral surface on the rear end side of the front body plate 3a.

On the front side of the front body plate 3a, a partition wall 7 is installed at a position recessed inward from the front surface of the skin plate 3a to divide the inside of the skin plate 3 into a face side and an inside side. The muddy water chamber 4 is provided on the face side of the skin plate 3 , that is, between the cutter board 2 and the partition wall 7 . The mud chamber 4 is a space (chamber) that takes in the earth and sand excavated by the rotation of the cutter board 2 and mixes it with the mud water supplied through the mud pipe 5 .

On the other hand, inside the skin plate 3, a cutter drive unit 10, a plurality of center-folding jacks 11a, a plurality of shield jacks 11b, an erector 12, a mud feed pipe 5, and a mud discharge pipe 6 are installed. It is

The cutter drive unit 10 is driven by the cutter drive motor 9 to rotate the cutter board 2 forward and backward. The center-folding jack 11a is a device that connects the front body plate 3a and the rear body plate 3b and corrects the propelling direction of the shield machine 1. As shown in FIG. The shield jack 11b applies a reaction force to the segment SG laid on the inner circumference of the tunnel behind the skin plate 3, pushes the segment SG backward, and advances the shield machine 1 including the skin plate 3. It is a device that generates the propulsion force of The erector 12 is a device that constructs a segment SG on the inner circumference of an excavated tunnel by gripping a plurality of pieces near the rear end inside the skin plate 3 and assembling them into a ring. The segment SG consists of, for example, a concrete segment, a steel segment, or a synthetic segment (synthetic structure of concrete and steel) that is an arc-shaped plate material, and a plurality of segments are arranged along the circumferential and axial directions of the tunnel. is installed in

The mud pipe 5 is a pipe for supplying muddy water into the muddy chamber 4, and is made of steel, for example. The tip of the mud pipe 5 (mud discharge port) penetrates the front inner upper portion of the partition wall 7 and reaches the mud chamber 4 . Thus, the mud water pressure-fed through the mud pipe 5 is supplied into the mud chamber 4 from the upper part of the front face of the shield machine 1 . On the other hand, the rear end of the mud pipe 5 extends toward the well of the tunnel, and the muddy water layer outside the tunnel is fed through a plurality of mud pumps (not shown) arranged at predetermined intervals along the way. (not shown). The mud tank is connected to a mud treatment device (not shown) outside the tunnel.

The mud discharge pipe 6 is a pipe for discharging mud water (mixed mud water of excavated soil and mud water) in the mud chamber 4 to the outside of the tunnel, and is made of steel, for example. The tip (mud absorption port) of the mud discharge pipe 6 penetrates the front inner lower portion of the partition wall 7 and reaches the mud chamber 4 . As a result, the mud water in the mud chamber 4 is discharged from the front inner lower portion of the shield machine 1 . On the other hand, the rear end of the sludge drain pipe 6 extends toward the pit of the tunnel, and a plurality of sludge drain pumps (not shown) arranged at predetermined intervals along the way are used to treat mud outside the tunnel. connected to the device. That is, the discharged mud water in the mud chamber 4 is sent to the mud water treatment device outside the tunnel through the mud discharge pipe 6, where it is separated into earth and sand and the mud water, the specific gravity and viscosity are adjusted, and then sent to the mud tank. Then, it is sent to the mud chamber 4 through the mud pipe 5 again.

A raking plate 8 is attached to the rear surface of the cutter board 2 so as to face the inside of the muddy water chamber 4 . The scraping plate 8 is rotated in the circumferential direction by the rotation of the cutter board 2 to scrape up the sludge deposited on the bottom of the muddy water chamber 4 and spread it in the muddy water.

In FIG. 1, a tail brush 3c is provided on the inner peripheral surface of the rear body plate 3b that constitutes the skin plate 3 at the rear portion in the traveling direction. The tail brushes 3c are made of, for example, steel wires or foamed urethane, and are provided in an annular shape at intervals in the traveling direction. The tail brush 3c extends inward with a length that contacts the outer peripheral surface of the segment SG. A seal chamber 13 is formed.

A sealing agent supply path (not shown) is provided for supplying a sealing agent such as grease pressure-fed from a pump (not shown) to the sealing chamber 13 . The gap between the outer peripheral surface of the segment SG and the inner peripheral surface of the skin plate 3 is sealed by filling the sealing agent into the sealing chamber 13 from the sealing agent supply passage. Underground water or the like is prevented from entering the skin plate 3 from the rear portion of the skin plate 3 during excavation work.

As shown in FIGS. 1 and 2, on the outer wall of the skin plate 3, a back-filling material such as a cement-based hardening material or solidifying material is supplied to the gap between the excavated hole behind the skin plate 3 and the segment SG. A back-filling material supply path (protruding portion) 14 is provided along the axial direction of the skin plate 3 for the purpose. By filling the gap with a back-filling material, ground subsidence is prevented, and furthermore, the segment SG and the natural ground form an integrated structure to prevent water leakage from the joint of the segment SG.

Further, as shown in FIG. 1, a plurality of protection bits 15 for protecting the back-filling material supply path 14 in the excavation process described later are installed in front of the back-filling material supply path 14 in the traveling direction of the shield machine 1. It is

Here, the backfilling material supply path 14 and the protection bit 15 will be described with reference to FIGS. 1 to 6. FIG. FIG. 3 is an explanatory view showing the backfilling material supply path and the protection bit provided in the shield machine of FIG. 1 by extracting them in a radial cross section of the skin plate, and FIG. 4 is one of the backfilling material supply paths and the protection bit. 5 is a cross-sectional view taken along line AA of FIG. 4, and FIG. 6 is an explanatory diagram showing the positional relationship between the back-filling material supply path and the protection bit.

As shown in these drawings, the back-filling material supply path 14 is provided on the outer wall of the rear body plate 3b that constitutes the skin plate 3. As shown in FIG. As shown in FIG. 3, the back-filling material supply passages 14 are arranged at two locations near the top of the rear body plate 3b and sandwiching the top of the rear body plate 3b when viewed in a radial cross section of the rear body plate 3b. . This is because the supply position of the back-filling material to the above-mentioned gap is set to two positions sandwiching the top of the rear body plate 3b, so that the back-filling material flows down along both sides of the outer peripheral wall of the segment SG and is evenly filled. This is to ensure that

The protection bit 15 is provided on the outer wall of the front body plate 3a that constitutes the skin plate 3. As shown in FIG. As shown in FIG. 4, these protection bits 15, which are provided in front of the back-filling material supply passage 14, are arranged with their long sides directed in the axial direction of the front body plate 3a in a plan view. Such guard bits 15 form three groups G1, G2, G3 that are superimposed in series and form forward-pointing arrow-shaped clusters. The protection bits 15 are of three different heights: the lowest protection bit 15a, the next lowest protection bit 15b, and the highest protection bit 15c.

The group G1 at the front stage is composed of protection bits 15a, the group G2 at the middle stage is composed of protection bits 15a at both ends and the other protection bits 15b, and the group G3 at the rear stage is composed of protection bits 15a at both ends and protection bits 15a next to them. Bit 15b and the others are composed of protection bit 15c. As shown in FIGS. 4 and 5, the protection bits 15 (15a, 15b, 15c) increase in height from the front to the rear on the same straight line L along the axial direction of the front body plate 3a. placed to be higher.

Furthermore, as shown in FIG. 6, in accordance with the shape of the back-filling material supply path 14 in which both ends in the width direction are inclined and lowered, when viewed in a radial cross section of the front body plate 3a, protective The bit 15a, the protection bit 15b next to it, and the protection bit 15c are arranged, and the height as a whole exceeds the height of the back-filling material supply path 14 in the width direction.

By arranging the protection bits 15 in this way, when the ground is excavated while rotating the cutter board 2 in the excavation process described later, the protection bits 15 excavate a region that cannot be excavated by the cutter board 2. Therefore, the back-filling material supply path 14 following the protection bit 15 is protected.

If the soil during excavation of the ground is very soft and there is no fear of damaging the back-filling material supply path 14, the protection bit 15 for protecting the back-filling material supply path 14 is not installed. It doesn't have to be.

Next, a tunnel excavation method according to the present embodiment using such a shield machine 1 will be described. Here, FIG. 7 is a side view showing the essential part of the starting shaft in the tunnel excavation method of the present embodiment, and FIG. 9 is a cross-sectional view taken along line BB of FIG. 8, and FIG. 10 is an explanatory diagram showing the positional relationship between the hole and the back-filling material supply path in the drilling process.

In the tunnel excavation method of the present embodiment, first, as shown in FIG. An earth retaining wall W1 is constructed of reinforced concrete reinforced with reinforcing material F (FIG. 8) in the portion where the earth retaining wall is excavated to form a starting port for entering the mountain (construction step). That is, although the starting shaft is surrounded by an earth retaining wall W2 made of reinforced concrete or steel, a different earth retaining wall W1 is constructed for the starting opening portion.

Here, in FIGS. 8 and 9, the reinforcing material F arranged in the retaining wall W1 is a high-strength reinforcing material (CFRT (carbon fiber reinforced plastic)) that can be cut by the cutter board 2 of the shield machine 1. Reinforcing material) F. As shown in FIG. 8, the reinforcement members F are arranged vertically and horizontally (FIG. 8), and as shown in FIG. That is, reinforcing bars F are arranged in two stages on the starting shaft side and two stages on the ground side, respectively, and the reinforcing members F in each stage are fastened with the width stopping bars T. As shown in FIG. However, the reinforcing material F does not need to be arranged in four stages, and can be set to an arbitrary number of stages.

In the construction process, an entrance packing (seal member) P for stopping water is installed on the inner peripheral edge of the pithead concrete C surrounding the outer periphery of the starting point, and the shield machine 1 excavates the earth retaining wall W1. A gap between the formed starting port E and the skin plate 3 of the shield machine 1 is sealed.

After the construction process is completed in this way, as shown in FIG. A hole is drilled in the earth retaining wall W1 (the earth retaining wall W1 made of reinforced concrete with reinforcing material F arranged therein) (drilling step). Here, the drilling depth (depth) is the position where the reinforcing material F closest to the ground in the retaining wall W1 is cut, but does not reach the ground (position where earth and sand do not flow in). This is because the reinforcing material F cannot be cut by the protection bit 15 that precedes the backfilling material supply path 14 when the shield machine 1 starts, so the reinforcing material F of the retaining wall W1 in the range concerned is removed in advance. This is to remove it.

The earth retaining wall W1 is drilled by rotating a core bit (cylindrical blade) of a core boring machine (not shown) at high speed (core drilling). As shown in FIG. 10, the hole H formed by core drilling is circular. Therefore, the range where the back-filling material supply path 14 hits is covered by continuous core boring in which line cutting is performed by connecting core drilling holes.

In addition, since the earth retaining wall W1 is thin and relatively fragile at the drilled hole H, it is desirable to fill the hole H with urethane (filling material). The filling material is not limited to urethane, and various materials having low strength and water resistance can be applied.

Prior to the drilling step, it is desirable to improve the ground by injecting a chemical solution (grout material) into the ground ahead of the drilling range. Soil improvement involves injecting a chemical solution through an injection pipe installed by boring or the like and solidifying it to fill the gaps between soil particles. In the present embodiment, as described above, since the thickness of the earth retaining wall W1 at the drilled hole H is thin, the thickness of the earth retaining wall W1 is reduced in order to prevent the earth pressure from destroying the part and allowing earth and sand to flow in. , ground improvement is carried out.

Here, the drilling process will be described in detail with reference to FIGS. 11 and 12. FIG. FIG. 11 is an explanatory view of the working state in the drilling process as viewed from the side of the shield machine, and FIG. 12 is an explanatory view of the working state in the drilling process as viewed from the top of the shield machine.

As shown in these drawings, in the drilling process, first, the cutter board 2 of the shield machine 1 is located in front of the entrance packing P, and a predetermined space ( The shield machine 1 is advanced to a position where a work space is formed. This is because by covering the starting port E with the cutter board 2, groundwater is prevented from entering the starting shaft in the event of water leakage during work.

Next, a temporary scaffolding Z is assembled in the work space formed by the cutter board 2 and the retaining wall W1. The worker Y can pass through the skin plate 3 from the manhatch of the shield machine 1 and reach the working space from the earth and sand inlet 2-6 (FIG. 2) of the cutter board 2. FIG.

Then, from above the temporary scaffolding Z, the earth retaining wall W1 is drilled by continuous core boring by the core boring machine M in the manner described above. After drilling, the temporary scaffolding Z is dismantled and withdrawn outside the machine.

Now, when the drilling process is completed, using the shield tunneling machine 1, the cutter board 2 is rotated to cut the earth retaining wall W1 made of reinforced concrete with the reinforcing material F arranged, and the earth retaining wall W1 is entered into the natural ground. excavation of earth and sand (excavation process). The shield machine 1 that has entered the ground moves forward while leaving the ring-shaped segment. Pour in filling material and fill.

In the shield machine 1 of the present embodiment provided with the protection bit 15, if the excavation process is executed while the protection bit 15 is exposed, the entrance packing P provided on the inner peripheral edge of the wellhead concrete C is damaged. There is a risk of Therefore, the protection bit 15 is covered with a covering material prior to the excavation process. As the covering material, a material such as resin mortar or putty that can be crushed by the earth retaining wall W1 when the shield machine 1 enters from the starting opening is used. Since these coating materials do not crush just enough to touch the entrance packing P, they pass through the entrance packing P without being damaged by the protection bit 15. is exposed, the protection bit 15 can perform its original function (the function of protecting the back-filling material supply path 14).

The step of covering the protective bit 15 may be performed at any time before the excavation step is performed, for example, in parallel with the above-described construction step or drilling step, or between these steps.

As described above, according to the present embodiment, the backfilling material supply path 14 provided on the outer wall of the skin plate 3 of the reinforced concrete earth retaining wall W1 in which the reinforcing material F is arranged is connected to the shield tunneling machine. After drilling the range hit by the start of 1, the cutter board 2 is rotated to cut the retaining wall W1 and enter the natural ground to excavate the earth and sand. When drilling the range where the shield machine is started, the filling material is injected into the hole H formed by drilling the earth retaining wall. It becomes possible to avoid becoming an obstacle when passing through the retaining wall W1.

As described above, the invention made by the present inventor was specifically described based on the embodiment, but the embodiment disclosed in this specification is an example in all respects, and is limited to the technology disclosed. not a thing That is, the technical scope of the present invention should not be construed in a restrictive manner based on the description of the above embodiments, but should be construed according to the description of the scope of claims. All modifications are included as long as they do not deviate from the description technology and equivalent technology and the gist of the claims.

For example, in the present embodiment, the back-filling material supply path 14 is shown as a projecting portion, but the projecting portion is not limited to this, and is provided so as to project from the outer wall of the skin plate 3, Various mechanisms and members located in areas that cannot be excavated by the cutter board 2 can be used as protrusions.

In the above description, the case where the present invention is applied to a mud pressure type shield machine has been described, but the present invention is not limited to this, and can be applied to other shield machines such as a mud pressure type shield machine. can be done. Moreover, the cutter board is not limited to the face plate type, and can be applied to the spoke type.

1 shield machine 2 cutter board (excavation means)
3 Skin plate 3a Front body plate 3b Rear body plate 3c Tail brush 4 Mud chamber 5 Mud feed pipe 14 Back-filling material supply path (projection)
15, 15a, 15b, 15c Protective bit C Pithead concrete E Starting point F Reinforcing material H Hole M Core boring machine P Entrance packing SG Segment W1 Retaining wall W2 Retaining wall Z Temporary scaffolding

Claims (5)

A construction process of constructing an earth retaining wall made of concrete in which reinforcing materials are arranged and which can be cut by a rotary excavating means installed at the tip of a shield machine at the starting opening of the starting shaft;
The projecting portion provided on the outer wall of the skin plate of the shield machine cuts the earth retaining wall in a range that hits when the shield machine starts moving, cuts the reinforcing material closest to the ground in the earth retaining wall, and A drilling step of drilling to a position that does not reach the
an excavation step of entering and excavating the natural ground after cutting the earth retaining wall with the excavating means using the shield machine;
has
In the drilling step, a filling material is injected into a hole formed by drilling the earth retaining wall.
A tunnel excavation method characterized by: The filling material is a filling material having water stopping properties,
The tunnel excavation method according to claim 1, characterized in that: A protective bit for excavating a range in which the projecting portion contacts the earth retaining wall in the excavation step is installed in front of the projecting portion in the traveling direction of the shield machine.
3. The tunnel excavation method according to claim 1 or 2, characterized in that: covering the protective bit with a cladding that is crushable by the retaining wall prior to the excavation step;
The tunnel excavation method according to claim 3, characterized in that: The projecting portion is provided along the axial direction of the outer wall of the skin plate of the shield machine, and supplies a backfill material to the gap between the excavation hole behind the skin plate and the segment installed in the excavation hole. which is a backfilling material supply path,
The tunnel excavation method according to any one of claims 1 to 4, characterized in that:

Images