JP2000345788A - Width widening method and blasting protection construction for tunnel in mountain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out a width widening work for the cross section of tunnel safely and quickly from an old tunnel to a new tunnel by using hot line. SOLUTION: After drilling a blasting hole with a drilling machine installed on the side of a new tunnel 3 at a cross section widening portion 4 as a boundary between the old tunnel 2 and the new tunnel 3, a cross section between the outer periphery of a protector 11 and the lining concrete of the old tunnel 2 is closed at the front protection partition wall 7 provided at the side of the old tunnel 2 cramping the cross section width widening portion 4. At the rear protection partition wall 8 provided at the side of the new tunnel 3 cramping the cross section width widening portion 4, a cross section between the outer periphery of the protector 11 and the lining concrete 5 of the new tunnel 3 is closed and a blasting surrounding portion 15 is formed. Within this blasting surrounding portion 15, the blasting work is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for widening a mountain tunnel and a blast protection structure, and more particularly to a method for widening a mountain tunnel and a blast protection method which enable the widening of a mountain tunnel by a blasting method to be carried out safely as hot-line work. Regarding the structure.

[0002]

2. Description of the Related Art In recent years, in order to cope with the renovation of an aging mountain tunnel or the high standardization (cross-section widening, lane increase) accompanying the increase in tunnel traffic, the cross-section widening work of an existing tunnel has been carried out. In the case where the target is a tunnel on a main road, the construction is often performed on a live line in consideration of the conventional traffic volume (the construction is performed in parallel with vehicle traffic enabled).

[0003] In this kind of tunnel widening work, in general, the lining of an existing tunnel (old tunnel) is crushed, and the ground around the lining is cut to a cross section of a new tunnel to perform excavation. In the construction work using lines, construction space is limited due to the necessity of installing protective equipment (hereinafter referred to as protector) for general vehicles passing through the old tunnel, signals, emergency equipment, and the like. For this reason, mechanical excavation that is easy to handle in a restricted narrow space is often used.

[0004]

However, under such construction conditions, a large-capacity large-scale construction machine to be applied to hard rock layers or the like cannot be carried in, and a sufficient construction speed cannot be secured by mechanical excavation. There are cases. In such a case, it is necessary to widen the cross section by the blasting method. However, when using the blasting method, measures were taken such as completely closing the tunnel. Also, in the case of hot-line construction, since various construction machines are arranged from the blasting point, which is the section where the cross section of the old and new tunnels change, in the front and rear direction of the tunnel, these machines are protected from flying stones when blasting There is a need. Another problem is that measures must be taken to reliably remove generated dust and generated gas from the working space.

[0005] Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to perform tunnel widening work for widening a cross section from an old tunnel to a new tunnel using a blasting method on a live line in a safe and prompt manner. It is an object of the present invention to provide a mountain tunnel widening method and a blast protection structure which can be performed.

[0006]

In order to achieve the above object, the present invention provides a protector having a gate shape in a predetermined range in the longitudinal direction of an existing old tunnel and a new tunnel in which the cross section of the old tunnel is widened. Installed, in the method of widening the mountain tunnel by blasting the widening of the tunnel section as a live line construction to allow vehicle traffic in the protector,
After a blast hole is drilled by a drilling machine installed on the new tunnel side at a cross-sectional widening portion that is a boundary between the old tunnel and the new tunnel, provided on the old tunnel side with the cross-sectional widening portion interposed therebetween. The cross section between the outer periphery of the protector and the lining concrete of the old tunnel is closed by the front protection partition, and the outer circumference of the protector and the new tunnel are closed by the rear protection partition provided on the side of the new tunnel across the widened section. The blasting surrounding portion is formed by closing the cross section between the lining concrete and the blasting surrounding portion, and the blasting operation is performed in the blasting surrounding portion.

[0007] As a structure used at that time, a protector installed in a gate shape in a predetermined range in the longitudinal direction of the existing old tunnel and a new tunnel whose cross section is widened, and an old tunnel and a new tunnel. A front protection partition supported by the protector on the old tunnel side with the cross-sectional widening portion serving as a boundary and having a movable edge on its outer periphery that can be in close contact with the lining concrete of the old tunnel, and the cross-sectional widening portion. A rear protective bulkhead having a door plate rotatably supported by the protector on the side of the new tunnel and capable of closing a cross section between the lining concrete of the new tunnel and the lining concrete of the new tunnel at the time of deployment; A blasting enclosure that is not affected by blasting is formed in the tunnel space sandwiched between the partition walls.

The movable edge of the front protective bulkhead accommodates a tube inside the cover, and follows the expansion and deformation of the tube so that the outer peripheral edge of the cover serving as the movable edge is brought into close contact with the lining concrete of the old tunnel. It is preferable to do so.

In the above case, it is preferable that a portion of the front protective partition facing the blasting surrounding portion has a multilayer flexible structure in which a reinforcing fiber sheet and an explosion-proof mat are stacked.

[0010] It is preferable that the front protective partition is further provided with a release-side partition plate having a box-shaped steel plate structure on the back surface of the blast-side partition plate having a multilayer flexible structure.

Further, it is preferable that an air guide port of a dust collector is provided on the open side partition plate.

On the other hand, it is preferable that the door plate of the rear protective bulkhead is deployed and folded through a drive device and a drive transmission means provided on the face plate of the protector.

[0013] At this time, it is preferable that the rear protective bulkhead is configured to transmit the operation of the hydraulic jack to the door plate via a link mechanism.

[0014] It is preferable that a shock absorbing means is interposed in a part of the drive transmitting means.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for widening a mountain tunnel and a blast protection structure according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a vertical sectional view of a tunnel provided with a blast protection structure 10 according to the present invention, in which a new tunnel 3 is excavated by widening the cross section of an old tunnel 2 by applying the structure. The figure shows a state in which the lining concrete 5 and a part of the surrounding ground 6 have been crushed by blasting at the cross-section widening portion 4 which is the boundary between the existing old tunnel 2 and the already widened new tunnel 3. It is shown.

In the present invention, live lines are constructed in the tunnels 2 and 3 to be constructed as described above. In order to secure a cross section of a vehicle passing through the tunnel, a protector 11 is provided in the longitudinal direction of the tunnel over a predetermined range between the old tunnel 2 and the new tunnel 3 with the cross-section widened portion 4 interposed therebetween. In this embodiment, the protector 11 is designed to have a total length of about 40 m. As shown in FIG. 2, the cross-sectional shape is a portal shape that secures the building limit of the passing vehicle, and portal frames 12 are erected at predetermined intervals in the longitudinal direction of the tunnel, and each portal frame 12 is attached to the outer surface. A steel plate 13 is attached so as to cover. Thereby, the overall rigidity of the protector 11 is maintained. In the present embodiment, a plurality of traveling crawlers 14 are provided on the legs of the protector 11. Thereby, it is possible to advance by self-propelled by a predetermined amount as the widening section progresses. The protector 11 may not be equipped with the traveling crawler 14 and may perform a predetermined movement by a towing device (not shown).

In the entire length of the protector 11 shown in FIG. 1, the cross-section widening portion 4 is located at a position about one-fourth from the end of the old tunnel 2. A front protection partition 7 and a rear protection partition 8 are respectively provided at front and rear positions separated by a predetermined distance in the longitudinal direction of the tunnel centering on the cross-sectional widened portion 4. The impact of the blasting does not extend beyond the area defined by these protective bulkheads 7 and 8. Hereinafter, in the present specification, the space defined by the protective barriers 7 and 8 is referred to as a blasting enclosure 15. Each of these protective partitions 7 and 8 includes a movable portion having a different configuration, which will be described later. When the protector 11 moves in the tunnel direction, a part of the partition is deformed or folded to be reduced, and the protective partition is placed between the protective partition and the lining. A predetermined gap (clearance) is provided. Further, when the blasting operation is performed in the cross-section widening portion 4, the outer peripheral edge thereof is in close contact with the tunnel lining surface, and the blasting surrounding portion 15 is defined in the partitioned space.

Hereinafter, the configuration of each of the protective bulkheads 7 and 8 as a blast protective structure of the present invention and various equipment attached to the protector 11 will be described with reference to the accompanying drawings. First, the front protection bulkhead 7 and its accompanying equipment will be described with reference to FIGS. As shown in FIG. 1, the front protective bulkhead 7 is composed of two bulkhead plates 20 and 30 and is perpendicular to the longitudinal axis of the protector 11 at a predetermined interval in the longitudinal direction of the tunnel, that is, the tunnel. The face plate 13 of the protector 11 is configured so as to form a wall surface that is in the cross-sectional direction.
Attached to.

These two partition plates consist of a blasting partition plate 20 and a release-side partition plate 3030. As shown in the cross-sectional view of the tunnel in FIG. 2, each partition plate has a gate-shaped protector 11 and a cross-sectional shape following the tunnel lining from the upper half arch to the side wall of the tunnel. It has a dimensional shape in which a predetermined amount of gap is secured between itself and the surface. Furthermore, movable edges described with reference to FIG. 3 are incorporated into the outer peripheral edges of the partition plates 20 and 30 so as to close the gap.

The sectional shapes of the two blast-side partition plates 20 and the release-side partition plate 30 are almost the same so that the inner space between the tunnel lining concrete and the protector 11 can be closed. Is set. The constituent members are set differently for each purpose.

The structure of the blast-side partition plate 20 will be described. FIG. 2 is a schematic sectional view showing the shape of the partition plate from the tunnel sectional direction, and FIG. 3 is a schematic partial perspective view showing the configuration of the blasting partition plate 20 and the release partition plate 30 described above. A plurality of support frames 21 are arranged radially from a center point (not shown) of the upper half arch of the tunnel. An air tube accommodating portion 22 is attached so as to connect the ends of the support frames 21 with the groove side of the channel steel facing outward.
The overall shape of the air tube housing 22 is substantially horseshoe-shaped, as shown in the sectional view of FIG. 2, in which the upper half arch of the tunnel and the vertical side wall are integrated. Further, an air tube 23 made of synthetic rubber is housed in the air tube housing 22 over the entire length of the housing. The cross section of the air tube 23 is always a circular tube, and when compressed air is supplied from an external pressure source P1, the cross section has a length that suppresses expansion deformation to the side as shown in FIG. It expands and deforms into a circular or elliptical cross-sectional shape.

Further, the whole of the air tube 23 and the air tube housing 22 is covered with a partition cover 24.
As shown, the partition cover 24 has a U-shaped cross section having an inner dimension substantially equal to the outer width of the air tube housing 22. The shape in the full length direction is set to an arch shape substantially equal to the shape in order to cover the air tube housing 22. Then, as shown in FIGS. 3 and 4, the air tube 23 slides following the cross-sectional deformation caused by the expansion, and protrudes to the tunnel lining concrete 5 side.
It can be adhered to the surface (FIG. 3 → FIG. 4).

The components of the blasting side partition plate 20 will be described. The blasting side partition plate 20 is designed to have a flexible structure mainly for absorbing shock. The blasting side partition plate 20 is composed of two reinforced fiber sheets 2 fixed to the lower end of the partition cover 24.
5 and a rubber-knitted, thick explosion-proof mat 26 as a backing sheet for the reinforcing fiber sheet 25. Among them, in this embodiment, an aromatic polyamide (aramid) fiber woven fabric is used as the reinforcing fiber sheet 25. Since this aramid fiber woven fabric has high impact resistance, there is almost no damage as a woven fabric even if a stepping stone hits during blasting. Also, two sheets (25A, 25B)
Because of the use, the impact when the flying stones collide is greatly reduced. Further, an explosion-proof mat 26 as a backing sheet is stacked on the back side (as viewed from the blasting side) of the reinforcing fiber sheet 25. The explosion-proof mat 26 is an impact-absorbing mat roughly knitted with a large-diameter synthetic rubber fiber and used as a known explosion-proof material. By laminating the sheet 25 and the mat 26 having the flexible structure, it is possible to substantially avoid the impact of the blasting and the influence of the flying objects on the support frame 21. As shown in FIGS. 3 and 4, the reinforcing fiber sheet 25 is always in a state where it can be slightly loosened, but tension is applied in accordance with the sliding of the partition cover 24 toward the tunnel lining side. Placed in state.

Next, components of the release-side partition plate 30 will be described. The release-side partition plate 30 is an auxiliary partition plate disposed on the back side of the blast-side partition plate 20. The open-side partition plate 30 blasts the fine dust and debris scattered over the gap of the partition cover 24 of the blast-side partition plate 20 into a blast surrounding portion 15.
The main purpose is to reduce the shock wave and blast sound generated at the time of blasting, and to simply seal the gas so that the back gas does not diffuse outside the blasting enclosure 15. The purpose is. In the present embodiment, the open side partition plate 30 is a box-shaped member in which two punched metals are used for the side plate 31. In the present embodiment, the side plate 31 is used.
Is filled with glass wool 32.

An air tube accommodating portion 33 is also fixed to the outer peripheral edge of the release-side partition plate 30, and an air tube 34 is accommodated in the same manner as the blast-side partition plate 20. An end of a cover 35 having a bellows-shaped side portion so as to cover the air tube 34 is a flange end 3 of the air tube receiving portion 33.
3a. The air tube 34 is also made of a synthetic rubber tube, and expands in cross section as shown in FIG. 4 when compressed air is supplied from an external pressure source P2. The outer surface 3 of the cover 35 according to the inflation deformation of the air tube 34.
5a adheres to the surface of the tunnel lining.

Further, an air guide port 37 of a dust collector 36 is provided in a part of the open side partition plate 30 so as to face the blasting enclosure 15. The dust collector 36 is mounted on a bracket 38 attached to the side plate 13 of the protector 11 as shown in FIGS. 1 and 2, and the blasting enclosure 15 defined by the front protection partition 7 and the rear protection partition 8. After blasting, the gas and dust are collected and exhausted to the outside through a filter (not shown). The release-side partition plate 30 is not indispensable, but is formed by the blast-side partition plate 20.
0 can be achieved, or all functions required for the front protective bulkhead 7 can be achieved by using a single bulkhead having the configuration added to the blasting bulkhead 20 described above. is there.

Next, the configuration of the rear protective partition 8 provided on the new tunnel 3 side will be described with reference to FIGS. 1 and 5 to 8. The partition plate 40 of the rear protective partition 8 is the protector 1
It comprises a plurality of door structures (40A to 40E) that can be opened and closed via movable parts provided on a part of the door. A drill jumbo 9 having a plurality of booms 9a is mounted on the protector 11 behind the rear protective partition 8 via various brackets. The drill jumbo 9 extends the boom 9a to the cross-sectionally widened portion 4 to drill a blast hole h having a predetermined drilling pattern as described later (see FIGS. 1 and 9).

In FIG. 5, the partition plate 40 of the rear protective partition 8 is developed to block the inner space section between the outer periphery of the protector 11 and the primary lining concrete of the new tunnel 3 in the inner space of the new tunnel 3. FIG. In the present embodiment, the largest partition plate 40A that covers the side wall of the protector 11 and the side wall of the new tunnel 3 is arranged, and a plurality of partition plates according to the shape of the upper half arch of the new tunnel 3 are provided. 40B to 40E. Each partition plate 40
(Abbreviated as 40A to 40E) can be rotated around a hinge (not shown) provided on the protector 11 side by an operation of a driving device (described later) attached to the protector 11 as described later, and is not shown. Each partition plate 40 can be opened and closed based on the operation signal of the driving device from the operation unit. By keeping all the partition plates 40 in the closed state, as shown in FIG.
The inner hollow section during the primary lining can be closed.

FIG. 6 is a tunnel cross-sectional view of the open state of each partition plate 40 viewed from the new tunnel 3 side. FIG. 3 shows all the partition plates 40 rotatably supported by the protector 11.
2 shows a state in which is folded at the surface position of the face plate 13 of the protector 11, the end face of the lining concrete 5 of the old tunnel 2, and the face face 4a of the cross-sectionally widened portion 4. A large number of blast holes h drilled in a predetermined drilling pattern are schematically shown on the face 4a. As shown in the drawing, the blasting at the cross-section widening portion 4 cuts and expands to the cross-section of the new tunnel 3.

Next, components of the partition plate 40 of the rear protective partition 8 will be described with reference to FIG. As shown in FIG. 7, this partition plate 40 also has a multilayer structure like the front protection partition 7, so that a large deformation or the like does not occur at the time of opening and closing so that the partition plate 40 of the door structure can be smoothly opened and closed. It is designed to have the member rigidity. In the present embodiment, a punching metal having a predetermined thickness stiffened by a shaped steel frame (not shown) is used as the door plate 42. A reinforcing fiber sheet 41 is disposed on the blasting side surface of the door plate so as to absorb an impact at the time of blasting. Further, an explosion-proof mat 43 is interposed between the reinforcing fiber sheet 41 and the door plate 41 on the back side. By interposing the explosion-proof mat 43, when a stepping stone or the like collides with the reinforcing fiber sheet 41, the sheet 41 does not directly contact the door plate 42, so that the reinforcing fiber sheet 41 is worn out, and the door plate 42 is deformed such as a dent. Can be prevented, and the durability of each member can be increased.

FIG. 8 is a partially enlarged view showing a structure for opening and closing each partition plate 40 of the door structure. A link member 44 of a link mechanism that enables an opening and closing operation is attached to a part of the outer peripheral frame of the door plate 42 of each partition plate 40.
The end of the link member 44 is connected to a cylinder rod 45a of a hydraulic cylinder 45 as a drive device capable of inputting a linear motion in a predetermined direction. The door plate 40 can be opened and closed according to the expansion and contraction of the cylinder rod 45a in the direction indicated by the arrow in the drawing. Some of the link members 44 include
A shock absorber 46 is interposed. In the present embodiment, a hydraulic absorber is attached to a part of the cylinder rod 45a, and even if a stepping stone or the like collides with the blast and a direct impact is applied to the partition plate 40, the impact is applied to the cylinder rod 45a.
The transmission to the hydraulic drive device 45 via the control unit can be blocked.

As the opening / closing drive device of the door structure, it is also possible to use, in addition to a hydraulic cylinder, a rotational force of an electric motor, a hydraulic motor, or the like, which is converted into a door opening / closing operation by gear means or the like.

Next, a method for widening a tunnel according to the present invention will be described with reference to FIGS. First, the protector 11 is moved to a predetermined position such that the widened section 4 is located at the center of the blasting enclosure 15 with both the front and rear protective barriers 7 and 8 being released.
The boom 9a of the drill jumbo 9 mounted on 1 is advanced to the position of the face 4a of the cross-sectionally widened portion 4, and a blast hole h (FIG. 6) is drilled in a predetermined drilling pattern (see FIG. 9). After the drilling of the blast hole h and the completion of the loading of the explosive, the drill jumbo 9 is retracted to the rear of the rear protection partition 8, and the blast side partition plate 20 of the front protection partition 7 and the air tube 2 of the release side partition plate 30.
3 and 34 (FIG. 3) are expanded, and the partition cover 24 and the cover 35 cover the tunnel lining concrete 5 and the partition plates 20 and 3.
The gap between 0 and 0 is closed. At the same time, a driving device (not shown) connected to each partition plate 40 of the rear protective partition 8 is operated to deploy each door structure 40 to close the tunnel section (see FIG. 10). Thereafter, as shown in FIG. 1, blasting is performed. After a lapse of a predetermined time, the partition cover 24 of the blasting side partition plate 20 is released, and the dust in the blasting surrounding portion 15 and the post-gas are collected and exhausted by the dust collector 36. I do.
When the atmosphere in the blast enclosure 15 has been substantially cleaned, the partition plate 40 of the rear protective partition 8 is folded to release the tunnel cross section. A construction machine (not shown) is carried in to the vicinity of the face 4a, the blasting part is shaped, and the scraps 18 accumulated on the invert are carried out of the tunnel pit. The primary lining concrete of the new tunnel 3 is constructed at the stage when the waste removal is completed, and one cycle is completed.

As described above, according to the present invention, it is possible to promptly and safely perform tunnel widening work without hindering traffic of general vehicles in live-line work.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing a tunnel tunnel widening method and a blast protection structure according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the tunnel taken along the line II-II of FIG. 1;

FIG. 3 is a partially enlarged perspective view showing a configuration of a movable portion cover of each partition plate of the front protection partition 7;

FIG. 4 is a partially enlarged perspective view showing a state in which an air tube in a movable portion cover shown in FIG. 3 is inflated and a gap between a tunnel lining and a partition plate is closed.

FIG. 5 is a cross-sectional view of the tunnel taken along the line VV in FIG. 1;

FIG. 6 is a cross-sectional view of the tunnel taken along the line VI-VI of FIG. 1;

FIG. 7 is a partially enlarged perspective view showing one embodiment of the constituent members of the partition plate of the rear protective partition.

FIG. 8 is a partially enlarged perspective view showing an embodiment of the constituent members of the partition plate of the rear protective partition.

FIG. 9 is a vertical sectional view of a tunnel showing a procedure for carrying out the method for widening the cross section of a mountain tunnel according to the present invention (when a blast hole is drilled).

FIG. 10 is a longitudinal sectional view of a tunnel showing a procedure for carrying out the method for widening a section of a mountain tunnel of the present invention (when the construction machine is retracted).

[Explanation of symbols]

 2 Old Tunnel 3 New Tunnel 4 Cross Section Widening Section 5 Old Tunnel Lining Concrete 7 Front Protective Partition Wall 8 Backward Protective Partition Wall 9 Drill Jumbo 10 Blasting Protective Structure 11 Protector 12 Gate Frame 15 Blasting Enclosure Section 20 Blasting Side Partition Plate 22, 33 Air Tube housing part 23, 34 Air tube 24 Partition cover 35 Cover 25, 41 Reinforced fiber sheet 26, 43 Explosion-proof mat 30 Release side partition plate 31 Side plate 36 Dust collector 37 Air guide port 40 Partition plate 42 Door plate 44 Link member 45 Hydraulic jack 46 Hydraulic absorber

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akira Komori 2nd Sanbancho, Chiyoda-ku, Tokyo Tobishima Construction Co., Ltd. (72) Inventor Toshiharu Sakurai 2nd Sanbancho, Chiyoda-ku, Tokyo Tobishima Construction Co., Ltd. (72) Inventor Kensaku Ichikawa 2nd Sanbancho, Chiyoda-ku, Tokyo Tobishima Construction Co., Ltd. (72) Inventor Mitsuo Masuda 2-1 Tsukudocho, Shinjuku-ku, Tokyo Kumagaya Gumi (72) Inventor Yukio Kakiuchi 2-1 Tsukudo-cho, Shinjuku-ku, Tokyo (72) Kumagaya-gumi, Inc. (72) Inventor Shigeo Kitahara 2-1 Tsukudo-cho, Shinjuku-ku, Tokyo, Japan (72) Inventor Hikozo Imaoka, Chuo, Tokyo 4-12-20, Nihonbashi-Honmachi-ku, Sato Kogyo Co., Ltd. Kyoto Chuo-ku, Nihonbashi Honcho 4-12-20 Sato Kogyo Co., Ltd. in the F-term (reference) 2D055 BB02 LA17

Claims (9)

[Claims] 1. A live line construction in which a gate-shaped protector is installed in a predetermined range in a longitudinal direction of a tunnel of an existing old tunnel and a new tunnel in which the cross section of the old tunnel is widened, and vehicle traffic is allowed in the protector. In a method of widening a mountain tunnel, the widening of a tunnel section is performed by a blasting method, a blast hole is drilled by a drilling machine installed on the side of the new tunnel in a cross-sectional widening portion that is a boundary between the old tunnel and the new tunnel. After that, while closing the cross section between the outer periphery of the protector and the lining concrete of the old tunnel with the front protective bulkhead provided on the old tunnel side with the cross section widened section therebetween, The rear protective barrier provided on the new tunnel side closes the cross section between the outer periphery of the protector and the lining concrete of the new tunnel to form a blasting enclosure, A method for widening a mountain tunnel, characterized in that blasting work is performed in an enclosure. 2. A cross section which is a gate-shaped protector installed in a predetermined range in a longitudinal direction of a tunnel of an existing old tunnel and a new tunnel having a cross section of the old tunnel widened, and a cross section serving as a boundary between the old tunnel and the new tunnel. A front protection partition supported by the protector on the old tunnel side with the widened portion interposed therebetween and having a movable edge on its outer periphery that can be in close contact with the lining concrete of the old tunnel, and the new tunnel side with the cross-sectional widened portion interposed therebetween. A rear protective bulkhead having a door plate rotatably supported by the protector of the new tunnel and capable of closing a cross section between the lining concrete of the new tunnel at the time of deployment and being sandwiched between the front protective bulkhead and the rear protective bulkhead. A blasting protection structure for a mountain tunnel, wherein a blasting surrounding portion which is not affected by blasting is formed in the tunnel space. 3. The movable edge of the front protective partition has a tube housed inside the cover, and follows the expansion and deformation of the tube, so that the outer peripheral edge of the cover serving as the movable edge is formed on the lining concrete of the old tunnel. 3. The blasting protection structure for a mountain tunnel according to claim 2, wherein the blasting protection structure is made in close contact. 4. A multi-layered flexible structure in which a reinforcing fiber sheet and an explosion-proof mat are superimposed on a portion of the front protective partition facing the blasting surrounding portion.
The blast protection structure of the mountain tunnel described. 5. The mountain tunnel according to claim 4, wherein said front protection partition is provided with a release-side partition plate having a box-shaped steel plate structure on the back side of a blast-side partition plate having a multilayer flexible structure. Blast protection structure. 6. The blast protection structure for a mountain tunnel according to claim 5, wherein an air guide port of a dust collector is provided on the open-side partition plate. 7. The mountain tunnel according to claim 2, wherein the door plate of the rear protective bulkhead is operated to be expanded and folded through a drive device and a drive transmission means provided on the protector face plate. Blast protection structure. 8. The blast protection structure for a mountain tunnel according to claim 7, wherein the rear protection bulkhead is adapted to transmit an operation of a hydraulic jack to the door plate via a link mechanism. 9. The blast protection structure for a mountain tunnel according to claim 7, wherein impact damping means is interposed in a part of said drive transmission means.