JP2001032671A - Tunnel prelining construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tunnel prelining construction method excellent in workability, economically executable and supporting the front loose ground at a part near a working face stably and uniformly by the driving of pipe bodies and hardening material filled in the ground around the pipe bodies and hardened. SOLUTION: A plurality of pipe bodies 3 are radially driven into the loose ground 7 around a tunnel T to be excavated, from a part near a working face, at the insert angle of 20-25 deg. to the axial direction of the tunnel T to support the load of the loose ground 7 by the axial force of the pipe bodies 3. Hardening material 9 formed of a urethane resin solution with excellent permeability and quick hardening property to the natural ground is filled in the loose ground 7 around the pipe bodies 3 through the inside of the pipe bodies 3 and hardened. The adjacent pipe bodies 3 are thereby made continuous through the improved ground made into lump form by the hardening material 9, so that the load of the upper ground is stably and positively supported, and the base end parts of the pipe bodies 3 are buried and fixed by a concrete lining layer without being cut off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stabilizing a loose ground existing in a ground in front of a face when excavating a tunnel.

[0002]

2. Description of the Related Art Efficient excavation of a tunnel leads to shortening of construction period and cost reduction. For this reason, a large-sized and high-performance excavating machine and a transport device tend to be introduced in a mountain tunnel. When the is operated efficiently, the cross-sectional area of excavation is inevitably increased. Generally, the smaller the face, the smaller the degree of influence of the geological weak surface that adversely affects the stability of the tunnel, and at the same time, the load bearing capacity of the shoring works appears earlier as compared with the case of full-section excavation. Therefore, the stability of the tunnel is improved, but when the excavated cross section becomes large, the face becomes relatively unstable compared to the conventional excavation method of the cross section, and therefore, the face that can exert an effect exceeding this demerit. An auxiliary stabilization method is required.

[0003] As such an auxiliary method, it is necessary to reduce the construction period by introducing a large-sized machine, and it is necessary to take measures to stabilize the face by a method that does not greatly disturb the construction cycle. Steel pipe injection type fore-billing, which is a type of receiving method, is adopted. And, according to this tunnel front receiving construction method, there is an advantage that tunnel construction can be performed using a normal excavating machine without requiring special construction machinery and skill, but the conventional tunnel front receiving method is shown in FIG. After the tunnel A having a predetermined length is excavated, the ring support B is constructed on the excavated wall surface, and then concrete is sprayed to form a concrete lining layer C having a predetermined thickness. A plurality of 12.5 m steel pipes D are radially driven toward the front face of the face so that the angle with respect to the tunnel axis direction is 5 °.
A so-called long-length receiving system is widely adopted.

[0004]

However, according to this construction method, since the setting angle of the steel pipe D with respect to the tunnel axis direction is extremely small at 5 °, the cast steel pipe D has both ends as supporting points. Acting as a beam, the load on the loose ground is supported by the bending rigidity of the steel pipe D. The steel pipe D has a material characteristic that is strong against axial force and tensile force but weak against bending. Therefore, in order to be able to withstand the bending load due to the loose ground, the diameter and thickness of the steel tube D are large. Since a large steel pipe must be used, the material cost is high and the cross section of the casting hole of the steel pipe D becomes large, so that the drilling operation requires a lot of time and labor, and the work efficiency is reduced. There is a point. Further, since the base end of the steel pipe D is projected from the concrete lining layer C into the tunnel, a cutting operation is required.

[0005] When the steel pipe D is to be driven at a low angle of 5 ° to the ground in front of the face as described above, the upper end surface of the drilling machine to be driven comes into contact with the tunnel excavation wall surface. Drilling at such a low angle cannot be performed, and therefore, a widened portion for receiving the upper end of the drilling machine on the tunnel excavation wall surface and eliminating contact with the upper end of the drilling machine must be excavated, In addition to the excavation work of the widened portion, a repair work after the casting of the steel pipe is required, which hinders rapid construction. In addition, widening the periphery of the face which is relatively unstable is not suitable for the method aimed at stabilizing the face, although the loosely ground ground is prevented by the previously cast steel pipe D. Furthermore, when the earth cover is small, there is a possibility that a large ground surface subsidence may occur immediately above the center of the tunnel.

The present invention has been made in view of such a problem, and an object of the present invention is to stably and uniformly apply a load on a loose ground near a face by an axial force of a casting pipe. It can be supported and has excellent workability,
An object of the present invention is to provide a tunnel pre-loading method that can be constructed economically.

[0007]

According to a first aspect of the present invention, there is provided a tunnel preloading method according to the first aspect of the present invention, wherein a tunnel is excavated to a predetermined length, and a tunnel peripheral wall near a face is cut. And a plurality of pipes are cast at an angle capable of supporting the loose load of the ground by the axial force of these pipes toward the front ground outside the planned tunnel section, and then through the pipes. A curable material is injected into the ground around the pipe body, and thereafter, the base end of each pipe body projecting from the peripheral wall surface of the tunnel is fixed to the peripheral wall surface of the tunnel.

Further, in the above tunnel preloading method, the invention according to claim 2 is characterized in that the pipe is radially driven at an angle of 20 to 25 ° with respect to the tunnel axis direction, and the load in the bending direction is applied to the pipe. Also, a large compressive load is applied in the axial direction, and the invention according to claim 3 is characterized in that a urethane resin liquid is used as a curable material injected into the ground through the pipe. It is assumed that.

According to a fourth aspect of the present invention, when the pipe is cast in the surrounding ground in front of the face, the base end is located near the outside of the section of the planned tunnel and the tip is in front of the face. It is characterized by being placed so that it is located in the expected loose ground area outside the planned tunnel section,
The invention according to claim 5 is that, after performing primary lining with primary shotcrete on the excavated tunnel peripheral wall surface, a pipe is cast, and the hardening material is injected into the ground around the pipe through the pipe. It is characterized in that the tube protruding from the primary lining layer is buried and fixed by a secondary lining layer made of secondary shotcrete without cutting the base end.
Further, in the invention according to claim 6, a steel ring support is provided in the primary and secondary lining layers in front of the base end of the cast pipe, and the primary and secondary lining layers are provided. The base end of the pipe is received by a steel ring support.

[0010]

[Function] After a tunnel is excavated to a predetermined length by an excavator, a ring support is installed on the excavation wall to support the excavation wall, and then the primary surface of the excavation wall is sprayed with concrete to remove the surface of the excavation wall. To prevent Thereafter, the pipe body is set at a predetermined angle (hereinafter, referred to as an angle) with respect to the tunnel axial direction from the peripheral wall surface of the tunnel in the vicinity of the face by the drilling machine toward the front ground, that is, the pipe at the time of being cast. The slack ground acting on the body is cast with a set angle at which the load in the axial direction is greater than the bending direction of the tubular body. As described above, it is desirable that the angle at which the load on the loose ground of the ground can be supported by the axial force of the pipe be set to 20 to 25 ° as described in claim 2.

A plurality of such pipes are driven radially at predetermined intervals in the circumferential direction of the tunnel, and after the setting, a hardening material, Preferably, a urethane resin liquid is injected and hardened to stabilize the ground, and all the pipes uniformly support the load on the loose ground above. It is desirable that the distal end of the pipe body be located in the area of the loose ground without penetrating outside the area of the loose ground. Thereafter, a secondary spraying with concrete is performed, and the base end of the pipe projecting from the concrete lining layer by the primary spraying is not cut off and buried in the concrete lining layer by the secondary spraying without being cut off. It is integrated with this concrete lining layer.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 and FIG. 2 show that the tunnel T is dug a predetermined length, and every time there is loose ground, a portion near the face 1 is cut. This shows a ground receiving structure in which a plurality of pipes 3 made of steel pipes are sequentially radiated from a tunnel peripheral wall surface 2 to a front ground of an outer upper peripheral portion from a planned tunnel cross section in a tunnel. The peripheral wall surface 2 is supported by steel ring supports 4 sequentially constructed every time a predetermined length of the tunnel T is excavated, and the tunnel peripheral wall surface 2 includes a primary lining layer 5 by spraying concrete, The primary lining layer 5 is provided with a secondary lining layer 6 by spraying concrete layered thereon.

Further, the angle of the pipe 3 cast on the ground around the tunnel with respect to the tunnel axis direction is 20 to 25 °, and its tip is located in the loose ground 7 such as gravel or silt layer existing around the tunnel. At the boundary between the area of the loose ground 7 and the upper ground 8 where no looseness has occurred, while the base end is received by the outer peripheral surface of the steel ring support 5 as shown in FIG. While being stopped, it penetrates through the primary lining layer 5 and sinks into the secondary lining layer 6, and is fixed to the secondary lining layer 6. Then, the pipe 3 is moved in the tunnel axial direction.
As a result of being driven at a cutting angle of 20 to 25 °, a loose load from the upper loose ground 7 is applied to these pipes 3 as described later.
The tube body 3 is made to act more in the compression direction of the tube axis than in the bending direction, and is configured to support a loose load by the axial force of the tube body 3.

The loose ground 7 around each tube 3 is improved into a massive ground 7 ′ by hardening of a curable material 9 made of urethane resin injected through the tube 4, and also in the front-back and circumferential directions. Improved ground 7 'around the adjacent pipe 3
Are integrated with each other to uniformly receive the load on the upper ground.

A tunnel receiving method for obtaining such a structure will be described with reference to FIGS. 4 to 9. As shown in FIG. 5, the cutting face 1 is excavated using an excavator 10 such as a road header. When the tunnel T is excavated for a predetermined length, a steel ring support 4 is installed near or in contact with the excavated face 1 as shown in FIG. To abut the tunnel peripheral wall surface 2 to support the tunnel peripheral wall surface 2. Thereafter, a concrete spraying machine 11 is used to perform primary spraying of concrete on the tunnel peripheral wall surface 2 between the steel ring support 4 and the steel ring support 4 previously constructed, to thereby obtain a primary material having a predetermined thickness. The lining layer 5 is formed. At this time, when the rock face of the face 1 is loose and the ground is loose, concrete is sprayed on the face 1 as necessary.

Next, it is determined whether or not it is necessary to preload the ground in front of the face by the tubular body 3. If the ground is relatively stable and no preload is necessary, the face 1 is excavated a predetermined length again, and the face is excavated. In the case where the surrounding ground is loose ground 7, as shown in FIG. 7, first, the rear part of the steel ring support 4 constructed near the face 1 by using a pipe driving machine 12 also serving as a drilling machine. A straight hole 13 is drilled from the tunnel peripheral wall surface 2 to the front ground outside the planned tunnel section at a predetermined angle with a 20 to 25 degree angle to the tunnel axis direction. Such holes 13 are formed radially at predetermined intervals in the circumferential direction in the upper peripheral portion of the tunnel peripheral wall surface 2.

Although the structure of the tube driving machine 12 which is also used as a drilling machine is well known, a brief description will be given. A guide base 16 supported so as to be vertically adjustable in angle in the vertical direction is attached to the boom 15, and the pipe driving machine 12 also serving as the drilling machine is disposed on the guide base 16. The punching rod (not shown) and the chuck portion of the tube 3 are configured to be rotated and hit by a drifter 12a that is movable in the front-rear direction.

At the time of drilling, the drill rod 12 with the bit attached to its tip is supported on the guide base 16 so as to be movable back and forth toward the longitudinal direction of the guide base 16 with the drifter 12a retracted. Together with the base end of the drifter 12
a, the traveling carriage 1 is moved to the vicinity of the face 1 so that the longitudinal direction of the rod body for drilling is directed to the drilling direction and set at a predetermined cutting angle, By rotating the rod body and advancing the drifter 12a while hitting the rear end face thereof, a hole 13 having a predetermined depth into which the pipe body 3 can be inserted is formed.

After drilling the holes 13, the rod body for drilling is removed, and then the pipe 3 is inserted into each hole 13.
As shown in FIG. 8, the pipe body 3 has a large number of injection holes 17 perforated at small intervals in the circumferential direction and the longitudinal direction in the pipe wall, and has an inside extending from the proximal end to the vicinity of the distal end. A resin pipe 18 made of vinyl chloride is inserted, and a small-diameter curable material injection hose 20 having a spiral mixer 19 therein is inserted into the resin pipe 18 at the end thereof. The portion is fixed to the resin tube 18 via the cap body 21 in a state where the portion protrudes from the tip of the resin tube 18. Furthermore, the resin pipe 18
A rubber packing 22 is mounted on the outer peripheral surface of the base end portion, and resin tube fixing packings 23, 23 pressed against the inner peripheral surface of the tube body 3 so as to sandwich the packer 22 are mounted. The tip of a curable material filling hose 24 communicates with the inside of the packer 22.

The operation of inserting the tube 3 into the hole 13 is as follows.
The tube 3 is disposed on the guide table 16 so that the base end of the tube 3 is gripped by the chuck of the drifter 12a, and the resin is drawn out of the resin tube 18 inserted into the tube 3. The hose 20 and the filling hose 24 are connected and communicated with a curable material supply source made of a urethane resin liquid. Thereafter, as shown in FIG. 7, the tube 3 is inserted into the hole 13 to a predetermined depth by driving the drifter 12a forward, and the base is supported on the outer peripheral surface of the steel ring support 4 as shown in FIG. Then, the curable material 9 made of a urethane resin liquid is supplied to the filling hose 24 and the packer 22 is expanded to be pressed against the inner peripheral surface of the tube 3, and the resin tube 18 is inserted into the tube 3. Fix firmly.

Further, when the curable material 9 made of a urethane resin liquid is supplied to the injection hose 20, the curable material 9 supplied to the injection hose 20 is stirred by the spiral mixer 19 from the distal end of the resin tube 18 to the tube 3. Is injected into the pipe 3 and filled into the pipe 3, and is injected into the gap between the pipe 3 and the hole 13 and the loose ground 7 around the pipe 3 from a number of injection holes 17 drilled in the pipe 3. A predetermined amount of the curable material 9
After the pipe 3 is injected, the pipe 3 is separated from the driller 12a side of the drilling and pipe setting machine 12 to complete the setting of one pipe 3, and thereafter, the tunnel in the vicinity of the cutting face 1 is similarly formed. The pipes 3 are inserted into all the holes 13 radially drilled in the upper peripheral portion of the peripheral wall surface 2, the casting operation is performed, and the hardening material is injected. The hardened material 9 that has penetrated into the loose ground 7 around the surroundings forms a solid improved ground 7 ′ that is continuous with each other in the circumferential direction.
It is intended to obtain a pre-receiving structure in which all the pipes 3 which are radially driven through the 7 'are made of resin evenly.

The work of placing the pipe 3 on the loose ground 7 is performed by first using the drilling machine 12 which is also used as a drilling machine.
After drilling a hole 13 having a larger diameter than a predetermined depth,
Although it is performed by inserting the pipe 3 into the inside, the pipe 3 may be loosened and driven into the ground 7 without drilling the hole 13 in advance. In any case, it is necessary to set the casting angle of the tubular body 3, that is, the cutting angle, within the range of 20 to 25 ° as described above.

If the insertion angle of the tube 3 is less than 20 °, the load acting in the direction perpendicular to the tube 3, that is, the bending stress increases, so that the diameter of the tube 3 is increased and the wall thickness is increased. Therefore, the cost of the tube is high and the casting operation takes a long time.

On the other hand, when the insertion angle of the tubular body 3 becomes 25 ° or more, the load acting on the tubular body 3 in the right angle direction decreases. It is not economical because the pipe length in the axial direction of the tunnel that can substantially support the ground above is shortened and the casting length necessary to obtain a desired receiving range becomes longer rather than changing the wall thickness. In addition, the casting takes a long time and the workability is deteriorated. In addition, the difference between the height of the tip of the cast pipe 3 with respect to the outer peripheral surface of the tunnel T and the height of the excavation scheduled top end position becomes large, and it is not possible to suppress the loosening of the ground occurring therebetween.

Therefore, as described above, it is desirable that the insertion angle of the pipe 3 is set in the range of 20 to 25 °. In practice, when excavating a tunnel where the loose ground 7 exists, the length is 6 °.
A plurality of steel pipes 3 are radially driven from the tunnel peripheral wall 2 in the vicinity of the face 1 at an angle of 20 to 25 ° and the periphery of the pipe 3 is passed through the inside of the pipe 3. When a curable material made of a urethane resin liquid was injected into the ground and allowed to penetrate and cure, the load acting in the perpendicular direction of the tube 3 was 0.722 kN, whereas the load acting in the axial direction of the tube 3 was applied. The compressive load was 32.401 kN, and it was found that the preload effect was exerted by the axial rigidity of the tube 3.

As described above, the pipes 3 are radially cast on the upper peripheral portion of the tunnel peripheral wall surface 2 in the vicinity of the cutting face 1 and the hardening material is injected into the loose ground 7 through each of the pipes 3. After that, without cutting the base end projecting slightly from the primary lining layer 5 into the tunnel T, as shown in FIG. The secondary lining layer 6 having a predetermined thickness is formed by performing a secondary spraying of the concrete on the tunnel peripheral wall surface 2 between the steel ring support 4 and the constructed steel ring support 4, so that the inside of the secondary lining layer 6 is formed. And is integrated with the secondary lining layer 6.

[0027]

As described above, according to the tunnel preloading method according to the first aspect of the present invention, the tunnel is excavated to a predetermined length, and then the front side of the tunnel peripheral wall near the face is outside the planned tunnel cross section. A plurality of pipes are cast toward the ground at an angle capable of supporting the loose load of the ground by the axial force of these pipes, and then hardened to the ground around the pipe through the pipes. Material is injected, and then the base end of each pipe projecting from the tunnel peripheral wall is fixed to the tunnel peripheral wall. It can be made to act more strongly in the axial direction than in the direction, and can be supported by the axial force. Therefore, the use of a small-diameter and thin-walled pipe can surely support the loosened ground, so that it is economical and pipe-shaped. Ability to cast body It may perform and can improve the workability of the tunnel.

Further, since the curable material is injected into the ground around the tube through the cast-in tube, the ground around the tube is loosened by the curable material that has penetrated and hardened into the ground. It is possible to improve the ground that does not occur, and the improved ground between adjacent pipes is integrated, so that all pipes can evenly bear the load of the upper ground through the improved ground, and the ground collapse It is possible to securely prevent the base end of the pipe projecting into the tunnel from the peripheral wall of the tunnel without cutting it off. I can do it.

According to the second aspect of the present invention, the pipe is radially driven at an angle of 20 to 25 ° with respect to the tunnel axis direction. A small-diameter and thin-walled pipe body and a pipe-laying machine can be used to perform the pipe work smoothly and efficiently without excavating the tunnel peripheral wall surface into a stepped shape at the time of installation. The effect of supporting the load on the loosened ground by the axial force and the effect of obtaining the desired pre-load range can be maximized.

In addition, since the urethane resin liquid is used as the curable material to be injected into and penetrated into the loose ground, the penetrability into the ground is excellent and the quick-hardening property is excellent. The ground can be stabilized quickly.

According to a fourth aspect of the present invention, the base end of the tubular body is located in the vicinity of the outside of the planned tunnel section and the leading end is located in the expected loose ground area outside the planned tunnel section in front of the face. So that not only the cutting operation of the base end of the tube is unnecessary, but also
The upper ground can be supported by the axial force of the tube in the direction of compression rather than in the direction of tension, so that it can be injected around the tube,
It is possible to form a supporting ground layer that is stable and integrated with the pipe for a long period of time without adversely affecting the improved ground layer made of a urethane resin that is weak against the tension that has been hardened.

According to the fifth aspect of the present invention, the excavated tunnel peripheral wall surface is provided with a primary lining layer of primary sprayed concrete, and then a pipe is driven into the pipe. After the curable material has been injected into the tube, it is buried and fixed by the secondary lining layer of secondary shotcrete without cutting the base end of the tube projecting from this primary lining layer. Therefore, the primary lining with primary shotcrete is applied to prevent the skin from falling off, and the pipe is cast on the smooth peripheral wall of the tunnel, so that the casting is performed safely and smoothly. In addition to the fact that the base end of the tube is buried and fixed by the secondary lining layer, not only the work of cutting the base end of the tube is unnecessary, but also the load acting on the tube Dispersed in the secondary lining layer It it is capable of forming a stable previously receiving structure and be.

The invention according to claim 6 is characterized in that a steel ring support is provided in the primary and secondary lining layers in front of the base end of the cast-in pipe, and these primary and secondary linings are provided. Since the base end of the pipe is received by the work layer and the steel ring support, the load acting in the circumferential direction on the primary and secondary lining layers by the steel ring support is strongly and It is possible to further improve the stability of the tunnel by uniformly supporting the tunnel.

[Brief description of the drawings]

FIG. 1 is a simplified longitudinal side view showing a tunnel receiving structure.

FIG. 2 is a simplified longitudinal front view thereof,

FIG. 3 is an enlarged vertical sectional side view of a face portion,

FIG. 4 is a flow chart of a tunnel precedent method;

FIG. 5 is a vertical cross-sectional side view of the state of excavation;

FIG. 6 is a longitudinal sectional side view showing a state where a primary lining is applied;

FIG. 7 is a longitudinal sectional side view in a state where a pipe is cast.

FIG. 8 is an enlarged vertical cross-sectional side view of the inside of the tubular body;

FIG. 9 is a longitudinal sectional side view showing a state in which a secondary lining is applied;

FIG. 10 is a simplified vertical side view showing a conventional example.

[Explanation of symbols]

 T Tunnel 1 Face 2 Tunnel peripheral wall 3 Tube 4 Steel ring support 5 Primary lining 6 Secondary lining 7 Loose ground 9 Hardening material

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[Procedure amendment]

[Submission date] July 28, 1999 (July 7, 1999
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of the Invention] Tunnel receiving method

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stabilizing a loose ground existing in a ground in front of a face when excavating a tunnel.

[0002]

2. Description of the Related Art Efficient excavation of a tunnel leads to shortening of construction period and cost reduction. For this reason, a large-sized and high-performance excavating machine and a transport device tend to be introduced in a mountain tunnel. When the is operated efficiently, the cross-sectional area of excavation is inevitably increased. Generally, the smaller the face, the smaller the degree of influence of the geological weak surface that adversely affects the stability of the tunnel, and at the same time, the load bearing capacity of the shoring works appears earlier as compared with the case of full-section excavation. Therefore, the stability of the tunnel is improved, but when the excavated cross section becomes large, the face becomes relatively unstable compared to the conventional excavation method of the cross section, and therefore, the face that can exert an effect exceeding this demerit. An auxiliary stabilization method is required.

[0003] As such an auxiliary method, it is necessary to reduce the construction period by introducing a large-sized machine, and it is necessary to take measures to stabilize the face by a method that does not greatly disturb the construction cycle. is a type of receiving method steel-injected Fore Pas Iringu is employed. And, according to this tunnel front receiving construction method, there is an advantage that tunnel construction can be performed using a normal excavating machine without requiring special construction machinery and skill, but the conventional tunnel front receiving method is shown in FIG. After the tunnel A having a predetermined length is excavated, the ring support B is constructed on the excavated wall surface, and then concrete is sprayed to form a concrete lining layer C having a predetermined thickness. A plurality of 12.5 m steel pipes D are radially driven toward the front face of the face so that the angle with respect to the tunnel axis direction is 5 °.
A so-called long-length receiving system is widely adopted.

[0004]

However, according to this construction method, since the setting angle of the steel pipe D with respect to the tunnel axis direction is extremely small at 5 °, the cast steel pipe D has both ends as supporting points. Acting as a beam, the load on the loose ground is supported by the bending rigidity of the steel pipe D. The steel pipe D has a property of being strong against a compressive force or a tensile force acting in the axial direction as a material property, but weak against a bending. Therefore, in order to withstand the bending load due to the loose ground, Since a steel pipe having a large diameter and a large wall thickness must be used, the material cost is high and the cross section of the casting hole of the steel pipe D becomes large. Is reduced. Further, since the base end of the steel pipe D is projected from the concrete lining layer C into the tunnel, a cutting operation is required.

[0005] When the steel pipe D is to be driven at a low angle of 5 ° to the ground in front of the face as described above, the upper end surface of the drilling machine to be driven comes into contact with the tunnel excavation wall surface. Drilling at such a low angle cannot be performed, and therefore, a widened portion for receiving the upper end of the drilling machine on the tunnel excavation wall surface and eliminating contact with the upper end of the drilling machine must be excavated, In addition to the excavation work of the widened portion, a repair work after the casting of the steel pipe is required, which hinders rapid construction. In addition, widening the periphery of the face which is relatively unstable is not suitable for the method aimed at stabilizing the face, although the loosely ground ground is prevented by the previously cast steel pipe D. Furthermore, when the earth cover is small, there is a possibility that a large ground surface subsidence may occur immediately above the center of the tunnel.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to stably and smoothly reduce the load on the loose ground in the vicinity of the face by the axial rigidity of the casting pipe. An object of the present invention is to provide a tunnel receiving method which can be uniformly supported, has excellent workability, and can be constructed economically.

[0007]

According to a first aspect of the present invention, there is provided a tunnel preloading method according to the first aspect of the present invention, wherein a tunnel is excavated to a predetermined length, and a tunnel peripheral wall near a face is cut. From the cross section of the tunnel outside the planned tunnel section
It is cast at an angle that can support the loose load of the ground with axial rigidity , then injects a hardening material into the ground around the pipe through the pipe, and then protrudes to the peripheral wall of the tunnel The base end of each tube is fixed to the peripheral wall of the tunnel.

Further, in the above tunnel preloading method, the invention according to claim 2 is characterized in that the pipe is radially driven at an angle of 20 to 25 ° with respect to the tunnel axis direction, and the load in the bending direction is applied to the pipe. Also, a large compressive load is applied in the axial direction, and the invention according to claim 3 is characterized in that a urethane resin liquid is used as a curable material injected into the ground through the pipe. It is assumed that.

According to a fourth aspect of the present invention, when the pipe is cast in the surrounding ground in front of the face, the base end is located near the outside of the section of the planned tunnel and the tip is in front of the face. It is characterized by being placed so that it is located in the expected loose ground area outside the planned tunnel section,
The invention according to claim 5 is that, after performing primary lining with primary shotcrete on the excavated tunnel peripheral wall surface, a pipe is cast, and the hardening material is injected into the ground around the pipe through the pipe. It is characterized in that the tube protruding from the primary lining layer is buried and fixed by a secondary lining layer made of secondary shotcrete without cutting the base end.
Further, in the invention according to claim 6, a steel ring support is provided in the primary and secondary lining layers in front of the base end of the cast pipe, and the primary and secondary lining layers are provided. The base end of the pipe is received by a steel ring support.

[0010]

[Function] After a tunnel is excavated to a predetermined length by an excavator, a ring support is installed on the excavation wall to support the excavation wall, and then the primary surface of the excavation wall is sprayed with concrete to remove the surface of the excavation wall. To prevent Thereafter, the pipe body is set at a predetermined angle (hereinafter, referred to as an angle) with respect to the tunnel axial direction from the peripheral wall surface of the tunnel in the vicinity of the face by the drilling machine toward the front ground, that is, the pipe at the time of being cast. The slack ground acting on the body is cast with a set angle at which the load in the axial direction is greater than the bending direction of the tubular body. As described above, it is desirable that the angle at which the load on the ground can be supported by the rigidity of the pipe body in the axial direction to support the load on the ground becomes 20 to 25 ° as described in claim 2.

A plurality of such pipes are driven radially at predetermined intervals in the circumferential direction of the tunnel, and after the setting, a hardening material, Preferably, a urethane resin liquid is injected and hardened to stabilize the ground, and all the pipes uniformly support the load on the loose ground above. It is desirable that the distal end of the pipe body be located in the area of the loose ground without penetrating outside the area of the loose ground. Thereafter, a secondary spraying with concrete is performed, and the base end of the pipe projecting from the concrete lining layer by the primary spraying is not cut off and buried in the concrete lining layer by the secondary spraying without being cut off. It is integrated with this concrete lining layer.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 and FIG. 2 show that the tunnel T is dug a predetermined length, and every time there is loose ground, a portion near the face 1 is cut. This shows a ground receiving structure in which a plurality of pipes 3 made of steel pipes are sequentially radiated from a tunnel peripheral wall surface 2 to a front ground of an outer upper peripheral portion from a planned tunnel cross section in a tunnel. The peripheral wall surface 2 is supported by steel ring supports 4 sequentially constructed every time a predetermined length of the tunnel T is excavated, and the tunnel peripheral wall surface 2 includes a primary lining layer 5 by spraying concrete, The primary lining layer 5 is provided with a secondary lining layer 6 by spraying concrete layered thereon.

Further, the angle of the pipe 3 cast on the ground around the tunnel with respect to the tunnel axis direction is 20 to 25 °, and its tip is located in the loose ground 7 such as gravel or silt layer existing around the tunnel. At the boundary between the area of the loose ground 7 and the upper ground 8 where no looseness has occurred, while the base end is received by the outer peripheral surface of the steel ring support 5 as shown in FIG. While being stopped, it penetrates through the primary lining layer 5 and sinks into the secondary lining layer 6, and is fixed to the secondary lining layer 6. Then, the pipe 3 is moved in the tunnel axial direction.
As a result of being driven at a cutting angle of 20 to 25 °, a loose load from the upper loose ground 7 is applied to these pipes 3 as described later.
The pipe 3 is made to act more in the compression direction of the tube axis than in the bending direction, and is configured to support a loose load with the axial rigidity of the pipe body 3.

The loose ground 7 around each tube 3 is improved into a massive ground 7 ′ by hardening of a curable material 9 made of urethane resin injected through the tube 4, and also in the front-back and circumferential directions. Improved ground 7 'around the adjacent pipe 3
Are integrated with each other to uniformly receive the load on the upper ground.

A tunnel receiving method for obtaining such a structure will be described with reference to FIGS. 4 to 9. As shown in FIG. 5, the cutting face 1 is excavated using an excavator 10 such as a road header. When the tunnel T is excavated for a predetermined length, a steel ring support 4 is installed near or in contact with the excavated face 1 as shown in FIG. To abut the tunnel peripheral wall surface 2 to support the tunnel peripheral wall surface 2. Thereafter, a concrete spraying machine 11 is used to perform primary spraying of concrete on the tunnel peripheral wall surface 2 between the steel ring support 4 and the steel ring support 4 previously constructed, to thereby obtain a primary material having a predetermined thickness. The lining layer 5 is formed. At this time, when the rock face of the face 1 is loose and the ground is loose, concrete is sprayed on the face 1 as necessary.

Next, it is determined whether or not it is necessary to preload the ground in front of the face by the tubular body 3. If the ground is relatively stable and no preload is necessary, the face 1 is excavated a predetermined length again, and the face is excavated. In the case where the surrounding ground is loose ground 7, as shown in FIG. 7, first, the rear part of the steel ring support 4 constructed near the face 1 by using a pipe driving machine 12 also serving as a drilling machine. A straight hole 13 is drilled from the tunnel peripheral wall surface 2 to the front ground outside the planned tunnel section at a predetermined angle with a 20 to 25 degree angle to the tunnel axis direction. Such holes 13 are formed radially at predetermined intervals in the circumferential direction in the upper peripheral portion of the tunnel peripheral wall surface 2.

Although the structure of the tube driving machine 12 which is also used as a drilling machine is well known, a brief description will be given. A guide base 16 supported so as to be vertically adjustable in angle in the vertical direction is attached to the boom 15, and the pipe driving machine 12 also serving as the drilling machine is disposed on the guide base 16. The punching rod (not shown) and the chuck portion of the tube 3 are configured to be rotated and hit by a drifter 12a that is movable in the front-rear direction.

At the time of drilling, the drill rod 12 with the bit attached to its tip is supported on the guide base 16 so as to be movable back and forth toward the longitudinal direction of the guide base 16 with the drifter 12a retracted. Together with the base end of the drifter 12
a, the traveling carriage 1 is moved to the vicinity of the face 1 so that the longitudinal direction of the rod body for drilling is directed to the drilling direction and set at a predetermined cutting angle, By rotating the rod body and advancing the drifter 12a while hitting the rear end face thereof, a hole 13 having a predetermined depth into which the pipe body 3 can be inserted is formed.

After drilling the holes 13, the rod body for drilling is removed, and then the pipe 3 is inserted into each hole 13.
As shown in FIG. 8, the pipe body 3 has a large number of injection holes 17 perforated at small intervals in the circumferential direction and the longitudinal direction in the pipe wall, and has an inside extending from the proximal end to the vicinity of the distal end. A resin pipe 18 made of vinyl chloride is inserted, and a small-diameter curable material injection hose 20 having a spiral mixer 19 therein is inserted into the resin pipe 18 at the end thereof. The portion is fixed to the resin tube 18 via the cap body 21 in a state where the portion protrudes from the tip of the resin tube 18. Furthermore, the resin pipe 18
A rubber packing 22 is mounted on the outer peripheral surface of the base end portion, and resin tube fixing packings 23, 23 pressed against the inner peripheral surface of the tube body 3 so as to sandwich the packer 22 are mounted. The tip of a curable material filling hose 24 communicates with the inside of the packer 22.

The operation of inserting the tube 3 into the hole 13 is as follows.
The tube 3 is disposed on the guide table 16 so that the base end of the tube 3 is gripped by the chuck of the drifter 12a, and the resin is drawn out of the resin tube 18 inserted into the tube 3. The hose 20 and the filling hose 24 are connected and communicated with a curable material supply source made of a urethane resin liquid. Thereafter, as shown in FIG. 7, the tube 3 is inserted into the hole 13 to a predetermined depth by driving the drifter 12a forward, and the base is supported on the outer peripheral surface of the steel ring support 4 as shown in FIG. Then, the curable material 9 made of a urethane resin liquid is supplied to the filling hose 24 and the packer 22 is expanded to be pressed against the inner peripheral surface of the tube 3, and the resin tube 18 is inserted into the tube 3. Fix firmly.

Further, when the curable material 9 made of a urethane resin liquid is supplied to the injection hose 20, the curable material 9 supplied to the injection hose 20 is stirred by the spiral mixer 19 from the distal end of the resin tube 18 to the tube 3. Is injected into the pipe 3 and filled into the pipe 3, and is injected into the gap between the pipe 3 and the hole 13 and the loose ground 7 around the pipe 3 from a number of injection holes 17 drilled in the pipe 3. A predetermined amount of the curable material 9
After the pipe 3 is injected, the pipe 3 is separated from the driller 12a side of the drilling and pipe setting machine 12 to complete the setting of one pipe 3, and thereafter, the tunnel in the vicinity of the cutting face 1 is similarly formed. The pipes 3 are inserted into all the holes 13 radially drilled in the upper peripheral portion of the peripheral wall surface 2, the casting operation is performed, and the hardening material is injected. The hardened material 9 that has penetrated into the loose ground 7 around the surroundings forms a solid improved ground 7 ′ that is continuous with each other in the circumferential direction.
It is intended to obtain a pre-receiving structure in which all the pipes 3 which are radially driven through the 7 'are made of resin evenly.

The work of placing the pipe 3 on the loose ground 7 is performed by first using the drilling machine 12 which is also used as a drilling machine.
After drilling a hole 13 having a larger diameter than a predetermined depth,
Although it is performed by inserting the pipe 3 into the inside, the pipe 3 may be loosened and driven into the ground 7 without drilling the hole 13 in advance. In any case, it is necessary to set the casting angle of the tubular body 3, that is, the cutting angle, within the range of 20 to 25 ° as described above.

If the insertion angle of the tube 3 is less than 20 °, the load acting in the direction perpendicular to the tube 3, that is, the bending stress increases, so that the diameter of the tube 3 is increased and the wall thickness is increased. Therefore, the cost of the tube is high and the casting operation takes a long time.

On the other hand, when the insertion angle of the tubular body 3 becomes 25 ° or more, the load acting on the tubular body 3 in the right angle direction decreases. It is not economical because the pipe length in the axial direction of the tunnel that can substantially support the ground above is shortened and the casting length necessary to obtain a desired receiving range becomes longer rather than changing the wall thickness. In addition, the casting takes a long time and the workability is deteriorated. In addition, the difference between the height of the tip of the cast pipe 3 with respect to the outer peripheral surface of the tunnel T and the height of the excavation scheduled top end position becomes large, and it is not possible to suppress the loosening of the ground occurring therebetween.

Therefore, as described above, it is desirable that the insertion angle of the pipe 3 is set in the range of 20 to 25 °. In practice, when excavating a tunnel where the loose ground 7 exists, the length is 6 °.
A plurality of steel pipes 3 are radially driven from the tunnel peripheral wall 2 in the vicinity of the face 1 at an angle of 20 to 25 ° and the periphery of the pipe 3 is passed through the inside of the pipe 3. When a curable material made of a urethane resin liquid was injected into the ground and allowed to penetrate and cure, the load acting in the perpendicular direction of the tube 3 was 0.722 kN, whereas the load acting in the axial direction of the tube 3 was applied. The compressive load was 32.401 kN, and it was found that the preload effect was exerted by the axial rigidity of the tube 3.

As described above, the pipes 3 are radially cast on the upper peripheral portion of the tunnel peripheral wall surface 2 in the vicinity of the cutting face 1 and the hardening material is injected into the loose ground 7 through each of the pipes 3. After that, without cutting the base end projecting slightly from the primary lining layer 5 into the tunnel T, as shown in FIG. The secondary lining layer 6 having a predetermined thickness is formed by performing a secondary spraying of the concrete on the tunnel peripheral wall surface 2 between the steel ring support 4 and the constructed steel ring support 4, so that the inside of the secondary lining layer 6 is formed. And is integrated with the secondary lining layer 6.

[0027]

As described above, according to the tunnel preloading method according to the first aspect of the present invention, the tunnel is excavated to a predetermined length, and then the front side of the tunnel peripheral wall near the face is outside the planned tunnel cross section. A plurality of pipes are cast toward the ground at an angle capable of supporting the loose load of the ground with the rigidity of the pipes in the axial direction , and then through the pipes to the ground around the pipes. It is characterized by injecting a curable material and then fixing the base end of each pipe projecting on the tunnel peripheral wall to the tunnel peripheral wall. Can be made to act more strongly in the axial direction than in the bending direction, and can be supported by the rigidity in the axial direction . Therefore, the use of a small-diameter and thin-walled pipe can reliably support the loose ground,
In addition to being economical, the work of placing the pipe can be performed efficiently and the workability of the tunnel can be improved.

Further, since the curable material is injected into the ground around the tube through the cast-in tube, the ground around the tube is loosened by the curable material that has penetrated and hardened into the ground. It is possible to improve the ground that does not occur, and the improved ground between adjacent pipes is integrated, so that all pipes can evenly bear the load of the upper ground through the improved ground, and the ground collapse It is possible to securely prevent the base end of the pipe projecting into the tunnel from the peripheral wall of the tunnel without cutting it off. I can do it.

According to the second aspect of the present invention, the pipe is radially driven at an angle of 20 to 25 ° with respect to the tunnel axis direction. A small-diameter and thin-walled pipe body and a pipe-laying machine can be used to perform the pipe work smoothly and efficiently without excavating the tunnel peripheral wall surface into a stepped shape at the time of installation. Axis direction
The effect of supporting the load on the loosened ground and the effect of obtaining a desired bearing range can be maximized by the directional rigidity .

In addition, since the urethane resin liquid is used as the curable material to be injected into and penetrated into the loose ground, the penetrability into the ground is excellent and the quick-hardening property is excellent. The ground can be stabilized quickly.

According to a fourth aspect of the present invention, the base end of the tubular body is located in the vicinity of the outside of the planned tunnel section and the leading end is located in the expected loose ground area outside the planned tunnel section in front of the face. So that not only the cutting operation of the base end of the tube is unnecessary, but also
The upper ground can be supported by the rigidity in the compression direction rather than the tension of the pipe, and therefore, the improved ground layer made of urethane resin that is weak against the injected and hardened tension around the pipe can be damaged. Without adverse effects,
It is possible to form a supporting ground layer that is stable for a long time and integrated with the pipe.

According to the fifth aspect of the present invention, the excavated tunnel peripheral wall surface is provided with a primary lining layer of primary sprayed concrete, and then a pipe is driven into the pipe. After the curable material has been injected into the tube, it is buried and fixed by the secondary lining layer of secondary shotcrete without cutting the base end of the tube projecting from this primary lining layer. Therefore, the primary lining with primary shotcrete is applied to prevent the skin from falling off, and the pipe is cast on the smooth peripheral wall of the tunnel, so that the casting is performed safely and smoothly. In addition to the fact that the base end of the tube is buried and fixed by the secondary lining layer, not only the work of cutting the base end of the tube is unnecessary, but also the load acting on the tube Dispersed in the secondary lining layer It it is capable of forming a stable previously receiving structure and be.

The invention according to claim 6 is characterized in that a steel ring support is provided in the primary and secondary lining layers in front of the base end of the cast-in pipe, and these primary and secondary linings are provided. Since the base end of the pipe is received by the work layer and the steel ring support, the load acting in the circumferential direction on the primary and secondary lining layers by the steel ring support is strongly and It is possible to further improve the stability of the tunnel by uniformly supporting the tunnel.

[Brief description of the drawings]

FIG. 1 is a simplified longitudinal side view showing a tunnel receiving structure.

FIG. 2 is a simplified longitudinal front view thereof,

FIG. 3 is an enlarged vertical sectional side view of a face portion,

FIG. 4 is a flow chart of a tunnel precedent method;

FIG. 5 is a vertical cross-sectional side view of the state of excavation;

FIG. 6 is a longitudinal sectional side view showing a state where a primary lining is applied;

FIG. 7 is a longitudinal sectional side view in a state where a pipe is cast.

FIG. 8 is an enlarged vertical cross-sectional side view of the inside of the tubular body;

FIG. 9 is a longitudinal sectional side view showing a state in which a secondary lining is applied;

FIG. 10 is a simplified vertical side view showing a conventional example.

[Description of Signs] T Tunnel 1 Face 2 Tunnel peripheral wall 3 Tube 4 Steel ring support 5 Primary lining 6 Secondary lining 7 Loose ground 9 Curable material

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hideki Nakamura 2-2-2 Matsuzaki-cho, Abeno-ku, Osaka-shi F-term (reference) 2D054 AC15 BA03 BA24 FA02 2D055 BA09 BB02 CA01 CA03 DB00 KB04

Claims (6)

[Claims] After excavating a tunnel for a predetermined length, a plurality of pipes are ground from the peripheral wall surface in the vicinity of the face to the ground in front of the cross section of the planned tunnel by the axial force of these pipes. Casting at an angle capable of supporting the mountain's loose load, then injecting hardening material into the pile surrounding the pipe through the pipe, and then the base end of each pipe protruding from the peripheral wall of the tunnel Is fixed to the peripheral wall surface of the tunnel. 2. The tube is set at 20 to 25 ° with respect to the axial direction of the tunnel.
The tunnel preceding method according to claim 1, wherein the tunnel is radiated at an angle of: 3. The method according to claim 1, wherein the curable material injected into the ground through the pipe is a urethane resin liquid. 4. Casting the pipe so that its proximal end is located near the outside of the planned tunnel section and its tip is located in the expected loose ground area outside the planned tunnel section in front of the face. The tunnel preceding method according to claim 1 or 2, characterized in that: 5. The excavated tunnel peripheral wall surface is subjected to primary lining with primary shotcrete, and then a pipe is cast therein.
After injecting the curable material into the pipe surrounding ground through the pipe, the base end of the pipe protruding from this primary lining layer is not cut and buried by the secondary lining layer of secondary shotcrete, The tunnel precedent method according to claim 1, wherein the tunnel is fixed. 6. A steel ring support is provided in the primary and secondary lining layers in front of the base end of the cast pipe, and the primary and secondary lining layers and the steel ring support are provided. The tunnel end receiving method according to claim 5, wherein the base end portion of the tubular body is received by the steps (1) and (2).