Support structure and tunnel construction method

Abstract

To reduce dangerous work of tunnel excavation and improve efficiency, and to develop a sufficient supporting function to prevent the ground from loosening.SOLUTION: The present invention relates to a supporting structure 1 used for supporting a tunnel. An injection pipe material 3 in which discharge holes 311 for a grout material G are formed at intervals in a length direction is arranged and fixed so as to extend along an outer peripheral surface of an arc-shaped supporting material 2 and in the length direction of the supporting material 2. At a lower portion 24 of the supporting material 2, one end of the injection pipe material 3, which bears the injection side of the grout material G, is introduced into an inner peripheral side of the supporting material 2. At a top end 25 of the supporting material 2, the other end of the injection pipe material 3, which bears an exhaust side during injection of the grout material G, is introduced into the inner peripheral side of the supporting material 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a support structure and a tunnel construction method that support earth pressure in a tunnel and prevent loosening of the ground. [Background technology]

[0002] In mountain tunnel excavation work, as shown in Figure 5(a), for example, a primary shotcrete 203 is applied to the tunnel wall every 1 m of an arch-shaped face 202 excavated in the natural ground 201, an arch-shaped steel support 204 is erected on the inner periphery of the primary shotcrete 203, a secondary shotcrete 205 is applied to fill in the spaces between the supports 204 on the inner periphery of the primary shotcrete 203, and rock bolts 206 are poured from the secondary shotcrete 205 toward the natural ground 201. Furthermore, behind that, a waterproof sheet 207 is laid on the inner periphery of the secondary shotcrete 205, and an arch-shaped lining concrete 208 is poured on the inner periphery of the waterproof sheet 207, while the invert is excavated and invert concrete 209 is poured, forming the arch-shaped lining concrete 208 and invert concrete 209 into a circumferential shape.

[0003] The support 204 erected during excavation work is generally erected in a semicircular shape using H-shaped steel support materials, so when spraying the secondary shotcrete 205, it cannot be sprayed on the outer periphery of the support 204, and a gap 210 remains between the primary shotcrete 203 or the natural ground 201 and the outer periphery of the support 204. The remaining gap 210 becomes a factor that allows the natural ground 201 to loosen (see Figure 5(b)).

[0004] Therefore, the preload shell method described in Patent Documents 1 and 2 is used as a means of filling the gap 210 and preventing loosening of the ground 201. In the preload shell method, as shown in Fig. 6, a pre-support 211 is used to prevent the ground 201 near the face from collapsing, and a support 204 is erected using support materials with bags 212 fixed along the outer periphery, thereby installing the bags 212 between the primary shotcrete 203 and the support 204. Non-shrink mortar 213 is then pressed into the bags 212 to fill the gap 210, allowing the ground load to be transmitted to the support 204 and enabling it to perform its support function. Bags 212 are also installed in the gaps between the legs of the support 204 and the ground 201, and the non-shrink mortar 213 is pressed in to fill the gaps. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-293195 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-295598 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when using the preloaded shell method to inject non-shrinkage mortar, a time-consuming process is required: premixing materials with water on-site to prepare the non-shrinkage mortar and then injecting it. This time-consuming process is carried out in a highly dangerous location where secondary shotcrete has not been applied to the tunnel wall immediately adjacent to the tunnel face. Furthermore, the preloaded shell method requires waiting until the non-shrinkage mortar is injected and filled into the outer periphery of the support before spraying the secondary shotcrete on the front side of the support in the tunnel excavation direction. This prevents the secondary shotcrete from being applied continuously, resulting in poor tunnel excavation efficiency. Therefore, a technology is needed that can reduce the dangers of tunnel excavation, improve efficiency, and provide the necessary support functions.

[0007] The present invention has been proposed in view of the above-mentioned problems, and aims to provide a support structure that can reduce the dangers of tunnel excavation work and improve efficiency, and that can exert sufficient support functions to prevent loosening of the ground, as well as a tunnel construction method that uses this support structure. [Means for solving the problem]

[0008] The support structure of the present invention is a support structure used for tunnel support, characterized in that injection pipe materials having grout material discharge holes formed at intervals along the length are arranged and fixed along the outer peripheral surface of the arc-shaped support material and extending in the length direction of the support material, and one end of the injection pipe material, which is responsible for the injection side of the grout material, is introduced into the inner peripheral side of the support material at the bottom of the support material, and the other end of the injection pipe material, which is responsible for the exhaust side when the grout material is injected, is introduced into the inner peripheral side of the support material at the top end of the support material. This allows grout to be injected from below into an injection pipe extending along the length of the arc-shaped support material along its outer periphery and then discharged through the discharge holes. This allows for more uniform filling and filling of the entire gap formed between the primary shotcrete or the natural ground and the outer periphery of the support. This allows for the support material and the natural ground to be integrated, providing sufficient support function for the support, preventing loosening of the natural ground, and stabilizing the natural ground. Furthermore, by guiding one end of the injection pipe (serving as the grout injection side) and the other end (serving as the exhaust side) on the inner periphery of the support material, secondary shotcrete can be applied to the area ahead of the support structure in the tunnel excavation direction before injecting grout into the erected support structure. This allows for preparation and injection of grout at a location where the secondary shotcrete has been formed and the tunnel wall has been stabilized. This reduces the risk of tunnel excavation work. Furthermore, since secondary sprayed concrete can be applied to the area in front of the support structure in the direction of tunnel excavation before the grout material is injected, the secondary sprayed concrete can be applied continuously to fill in the gaps between the supports, improving the efficiency of tunnel excavation work and reducing construction costs.

[0009] The support structure of the present invention is characterized in that one end and the other end of the injection pipe material are introduced into the inner side of the support material through through holes formed respectively in the outer flange and inner flange of the support material, which has an H-shaped cross section. This allows one end of the injection pipe material that handles the injection side of the grout material and the other end of the injection pipe material that handles the exhaust side to be more reliably introduced into the inner periphery of the support material, stabilizing the introduced state.

[0010] The support structure of the present invention is characterized in that one end and the other end of the injection pipe material are introduced into the inner peripheral side of the support material through the outside of the width direction of the support material. This allows one end of the injection pipe, which is responsible for injecting the grout material, and the other end of the injection pipe, which is responsible for the exhaust side, to be introduced to the inner periphery of the support material without any special processing of the support material.In addition, since the support can be constructed using support material without cross-sectional defects, the strength required for the support can be reliably obtained.

[0011] The tunnel construction method of the present invention is a tunnel construction method using the support structure of the present invention, and is characterized by comprising: a first step of erecting the support structure into the excavated tunnel space; a second step of spraying shotcrete on the front side of the support structure in the tunnel excavation direction; and a third step of injecting the grout material from one end of the injection pipe material of the support structure, checking the return of the grout material from the other end of the injection pipe material, and filling the gap between the support material and the ground with the grout material. According to this, by checking the return of the grout material from the other end of the injection pipe material placed at the top end of the support material and then filling the grout material, the grout material can be filled more uniformly and reliably throughout the entire gap formed between the tunnel's primary sprayed concrete or the ground and the outer surface of the support.

[0012] In the tunnel construction method of the present invention, in the first step, the first support structure is erected, and The first The second support structure is erected in front of the tunnel excavation direction of the support structure and immediately adjacent to the face of the tunnel space, and in the second step, The first Shoring structure and The second Spray concrete between the support structure and the concrete, and in the third step, The first Injecting the grout material from one end of the injection pipe of the support structure and checking the return of the grout material from the other end of the injection pipe; The first The grout material is filled into gaps between the support material of the support structure and the natural ground. According to this, by preparing and injecting grout into the first support structure, which is located away from the second support structure closest to the tunnel face, it is possible to prepare and inject grout at a location further away from the tunnel face, where the ground is prone to collapse. This further reduces the risk of dangerous tunnel excavation work. [Effects of the Invention]

[0013] According to the support structure or tunnel construction method of the present invention, it is possible to reduce the danger of tunnel excavation work and improve efficiency, and it is possible to exert sufficient support function and prevent loosening of the ground. [Brief explanation of the drawings]

[0014] [Figure 1] 1A is a schematic front view of a support structure according to an embodiment of the present invention, and FIG. 1B is a schematic plan view of the support structure according to the embodiment. [Figure 2] 1A is a cross-sectional view of a support material used in the support structure of the embodiment, and FIG. 1B is a partial view of the support material of FIG. 1A viewed from the outer flange side. [Figure 3] FIG. 2 is an enlarged view of a grout injection portion in the support structure of the embodiment. [Figure 4] 1(a) to 1(c) are schematic explanatory diagrams of the steps of a tunnel construction method using a support structure according to an embodiment. [Figure 5] (a) is a cross-sectional explanatory diagram of the tunnel structure formed by conventional tunnel excavation work, and (b) is a cross-sectional explanatory diagram explaining the gaps on the outer surface of the support structure formed by conventional tunnel excavation work. [Figure 6] A conceptual diagram of a structure formed using a conventional preload shell construction method. DETAILED DESCRIPTION OF THE INVENTION

[0015] [Support structure and tunnel construction method of the embodiment] The support structure 1 of an embodiment of the present invention is used for tunnel support, and as shown in Figures 1 to 3, is composed of an arc-shaped support material 2 and an injection pipe material 3 that is arranged along the outer surface of the arc-shaped support material 2 and extends in the longitudinal direction of the support material 2 and is fixed to the support material 2.

[0016] In this example, the support material 2 is a steel material that is H-shaped in cross section and is formed in an arc shape of approximately 1 / 4 of a circle. The support material 2 has an outer flange 22 formed on the outer periphery of a web 21, and an inner flange 23 formed on the inner periphery of the web 21. Through holes 26 for introducing the injection pipe material 3 into the inner periphery of the support material 2 are formed at corresponding positions on the lower parts 24 of the outer flange 22 and the inner flange 23, and at corresponding positions on the top ends 25 of the outer flange 22 and the inner flange 23.

[0017] In this example, the support material 2 has a joint plate 27 fixed to the tip on the top end 25 side. Then, by abutting the joint plates 27·27 of a pair of support materials 2·2 and fixing the abutting joint plates 27·27 together with bolts or the like, the pair of support materials 2·2 are erected in an arch shape in the tunnel space T formed in the natural ground 100, thereby forming a support.

[0018] The injection pipe material 3 is composed of an injection hose 31 for grout material G that can be bent along the arc-shaped outer peripheral surface of the support material 2, and the injection hose 31 has discharge holes 311 for the grout material G formed at intervals along its length. The injection hose 31 is arranged so as to follow the outer peripheral surface of the arc-shaped support material 2 and extend in the length direction of the support material 2, and is fixed to the support material 2 with a fixing band 4 such as a rubber band by wrapping the fixing band 4 around the support material 2 and the injection hose 31. When the injection hose 31 is fixed with the fixing band 4, it is preferable to use a pressure-resistant hose for the injection hose 31 so that it does not collapse when pressure is applied from outside the fixing band 4, and for example, a pressure-resistant hose such as a Tetron braided hose made of reinforced Tetron cord reinforced in a mesh form is recommended ("Tetron" is a registered trademark).

[0019] Furthermore, the injection pipe 3 of this example is provided with an introduction section 32 for introducing the injection pipe 3 into the inner periphery of the support material 2, and the introduction sections 32 are provided at positions corresponding to the lower part 24 of the support material 2 and the top end 25 of the support material 2, respectively. As shown in Figure 3, the introduction section 32 of this example is composed of an introduction pipe 321 such as a steel pipe that is inserted into the through holes 26, 26 at corresponding positions in the outer periphery flange 22 and the inner periphery flange 23, an elbow joint 322 that connects the outer periphery end of the introduction pipe 321 to the lower part 24 side end of the injection hose 31 so as to communicate with each other, and a nipple 323 provided at the inner periphery end of the introduction pipe 321.

[0020] That is, in the lower part 24 of the support material 2, an introduction part 32 composed of an elbow joint 322, an introduction pipe 321, and a nipple 323, which corresponds to one end of the injection pipe material 3 that is responsible for the injection side of the grout material G, is introduced into the inner peripheral side of the support material 2 through the corresponding through holes 26 in the outer peripheral flange 22 and the inner peripheral flange 23. A coupling 52 such as a one-touch coupling provided at the tip of a pressurized hose 51 for the grout material G is connected to the nipple 323 of the introduction part 32 that is responsible for the injection side of the grout material G, and the grout material G is injected from the pressurized hose 51 into the introduction pipe 321, the elbow joint 322, and the lower part 24 side of the injection hose 31.

[0021] Furthermore, at the top end 25 of the support material 2, an introduction section 32 consisting of an elbow joint 322, an introduction pipe 321, and a nipple 323, which corresponds to the other end of the injection pipe material 3 that serves as the exhaust side when injecting the grout material G, is introduced to the inner peripheral side of the support material 2 through the corresponding through holes 26 in the outer peripheral flange 22 and the inner peripheral flange 23. The nipple 323 of the introduction section 32 that serves as the exhaust side when injecting the grout material G is used to exhaust air when the grout material G is injected, and this nipple 323 is also used to confirm the return of the grout material G, which indicates that a sufficient amount of grout material G has been filled when the grout material G is injected and filled.

[0022] Next, a tunnel construction method using the shoring structure 1 of this embodiment will be described. First, as shown in Figure 4(a), the natural ground 100 is excavated to form a tunnel space T, a primary shotcrete 102 is sprayed onto the inner periphery of a tunnel wall 101, and the shoring structure 1 is erected up to the nearest tunnel face 103. In this example, while erecting a first shoring structure 1a, a second shoring structure 1b is erected in front of the first shoring structure 1a in the tunnel excavation direction, just near the tunnel face 103 in the tunnel space T.

[0023] Furthermore, secondary shotcrete 104 is sprayed on the front side of the first shoring structure 1a in the tunnel excavation direction, and secondary shotcrete 104 is sprayed between the first shoring structure 1a and the second shoring structure 1b, and secondary shotcrete 104 is provided so as to cover the primary shotcrete 102 or the hole wall 101 of the natural ground 100 in the area behind the second shoring structure 1b in the tunnel excavation direction (see FIG. 4(b)). With this secondary shotcrete 104 provided, voids 105 are formed both between the outer circumferential surface of the shoring material 2 of the first shoring structure 1a and the primary shotcrete 102 or the hole wall 101, and between the outer circumferential surface of the shoring material 2 of the second shoring structure 1b and the primary shotcrete 102 or the hole wall 101.

[0024] Then, for the first support structure 1a, which is located away from the working face 103 than the second support structure 1b and has a secondary shotcrete 104 provided in front of it, grout material G is injected from an introduction port 32 corresponding to one end of an injection pipe 3 located at the bottom 24 of the support material 2, and the grout material G is injected into the injection hose 31 while venting air from an introduction port 32 corresponding to the other end of the injection pipe 3 located at the top end 25 of the support material 2. A highly fluid, early-strength-developing, non-shrink cement-based material is preferably used as the grout material G. The injected grout material G is discharged from the discharge port 311 of the injection hose 31 and fills the voids 105 (see Figures 4(c) and 1).

[0025] The injection of the grout material G continues, and when the return of the grout material G from the introduction part 32, which corresponds to the other end of the injection pipe material 3 arranged at the top end 25 of the support material 2, is confirmed, the filling of the grout material G into the gap 105 between the support material 2 of the first support structure 1a and the primary shotcrete 102 or the hole wall 101 of the natural ground 100 is completed (see Figure 4(c) and Figure 1). This injection and filling of the grout material G is performed for both of the pair of support structures 1·1 that make up the arch-shaped support.

[0026] According to this embodiment, grout material G is injected from below into the injection pipe 3 extending in the lengthwise direction of the shoring material 2 along the outer circumferential surface of the arc-shaped shoring material 2, and the grout material G is discharged from the discharge holes 311, thereby making it possible to more uniformly fill and fill the entire gap 105 formed between the tunnel's primary shotcrete 102 or the ground 100 and the outer circumferential surface of the shoring. Therefore, the shoring made up of the shoring material 2 and the ground 100 are integrated, allowing the shoring to exhibit sufficient shoring function, preventing loosening of the ground 100, and stabilizing the ground 100.

[0027] Furthermore, by introducing one end of the injection pipe 3, which is responsible for the injection side of the grout material G, and the other end of the injection pipe 3, which is responsible for the exhaust side, into the inner periphery of the support material 2, it is possible to apply secondary shotcrete 104 to the area ahead of the support structure 1 in the tunnel excavation direction before injecting grout into the erected support structure 1, such as the first support structure 1a, and to prepare and inject grout material G at a location where the secondary shotcrete 104 has been formed and the stability of the tunnel wall 101 has been increased. This makes it possible to reduce the risk of tunnel excavation work.

[0028] Furthermore, since the secondary sprayed concrete 104 can be applied to the area in front of the support structure 1 in the tunnel excavation direction before the injection of the grout material G, such as the first support structure 1a, the secondary sprayed concrete 104 can be applied continuously to fill in the gaps between the supports, thereby improving the efficiency of the tunnel excavation work and reducing construction costs.

[0029] Furthermore, by introducing one end and the other end of the injection pipe material 3 into the inner periphery of the support material 2 through the through holes 26 formed in the outer peripheral flange 22 and the inner peripheral flange 23 of the support material 2, respectively, one end of the injection pipe material 3 that handles the injection side of the grout material G and the other end of the injection pipe material 3 that handles the exhaust side can be introduced more reliably into the inner periphery of the support material 2, and the introduced state can be stabilized.

[0030] Furthermore, according to the tunnel construction method using the support structure 1 of this embodiment, by checking the return of grout material G from the other end of the injection pipe material 3 arranged at the top end 25 of the support material 2 and then filling the grout material G, the grout material G can be filled more uniformly and reliably throughout the entire gap 105 formed between the tunnel's primary sprayed concrete 102 or the ground 100 and the outer surface of the support.

[0031] Furthermore, by preparing and injecting the grout material G into the first support structure 1a, which is away from the second support structure 1b closest to the tunnel face 103, it is possible to prepare and inject the grout material G at a location farther away from the tunnel face 103, where the natural ground 100 is prone to collapse. This makes it possible to further reduce the risk of dangerous tunnel excavation work.

[0032] [Scope of the invention disclosed herein] The inventions disclosed in this specification include, in addition to the individual inventions and embodiments listed as inventions, those specified by modifying partial contents of these with other contents disclosed in this specification, those specified by adding other contents disclosed in this specification to these contents, or those specified by deleting partial contents of these to the extent that partial effects can be obtained and creating a generic concept. The inventions disclosed in this specification also include the following modifications and additions.

[0033] For example, in the above embodiment, one end and the other end of the injection pipe 3 are introduced into the inner periphery of the support material 2 by means of the corresponding through holes 26 in the outer flange 22 and the inner flange 23, and the introduction portions 32 provided at the end of the injection hose 31 on the lower portion 24 side and the end on the top end 25 side, respectively. However, a configuration in which one end of the injection pipe 3 responsible for the injection side of the grout material G and the other end of the injection pipe 2 responsible for the exhaust side are introduced into the inner periphery of the support material 2 is appropriate within the scope of the spirit of the present invention. For example, it is also suitable as a structure for a modified support structure 1 in which the injection pipe 3 is composed only of the injection hose 31, and one end of the injection hose 31 responsible for the injection side of the grout material G is introduced into the inner periphery of the support material 2 via the outside in the width direction of the support material 2, and the other end of the injection hose 31 responsible for the exhaust side is introduced into the inner periphery of the support material 2 via the outside in the width direction of the support material 2.

[0034] By using this modified structure, one end of the injection pipe material that handles the injection side of the grout material G and the other end of the injection pipe material that handles the exhaust side can be introduced to the inner periphery of the support material without any special processing such as through-hole 26 in the support material. Also, since the support can be constructed using support material that does not have cross-sectional defects such as through-hole 26, the strength required for the support can be reliably obtained.

[0035] Furthermore, the support material in the support structure of the present invention is not limited to the support material 2 in the above embodiment, but may be any appropriate arc-shaped support material composed of multiple members or a single member and having a lower portion and a top portion. [Industrial Applicability]

[0036] The present invention can be used to fill gaps formed between the back of a tunnel support and the ground or primary sprayed concrete with grout material, thereby preventing loosening of the ground. [Explanation of symbols]

[0037] DESCRIPTION OF SYMBOLS 1, 1a, 1b... Shoring structure 2... Shoring material 21... Web 22... Outer peripheral flange 23... Inner peripheral flange 24... Lower portion 25... Top end 26... Through hole 27... Joint plate 3... Injection pipe material 31... Injection hose 311... Discharge hole 32... Introduction portion 321... Introduction pipe 322... Elbow joint 323... Nipple 4... Fixing band 51... Pressure hose 52... Coupling 100... Ground 101... Tunnel wall 102... Primary shotcrete 103... Face 104... Secondary shotcrete 105... Void T... Tunnel space G... Grout material 201... Ground 202... Face 203... Primary shotcrete 204... Shoring 205... Secondary shotcrete 206... Rock bolt 207... Waterproof sheet 208... Lining concrete 209... Invert concrete 210... Void 211... Pre-support 212... Bag body 213... Non-shrinkage mortar

Claims

1. A support structure used for tunnel support, An injection pipe material having grout discharge holes formed at intervals in the longitudinal direction is arranged and fixed along the outer peripheral surface of the arc-shaped support material and extending in the longitudinal direction of the support material, At the bottom of the support material, one end of the injection pipe material that serves as the injection side of the grout material is introduced into the inner periphery of the support material, A support structure characterized in that the other end of the injection pipe material, which serves as the exhaust side when injecting the grout material, is introduced into the inner side of the support material at the top end of the support material.

2. The support structure according to claim 1, characterized in that one end and the other end of the injection pipe material are introduced into the inner side of the support material through through holes formed respectively in the outer flange and the inner flange of the support material, which is H-shaped in cross section.

3. A support structure as described in claim 1, characterized in that one end and the other end of the injection pipe material are introduced into the inner side of the support material through the outside in the width direction of the support material.

4. A tunnel construction method using the support structure according to any one of claims 1 to 3, a first step of erecting the support structure in the excavated tunnel space; a second step of spraying shotcrete on the front side of the support structure in the tunnel excavation direction; a third step of injecting the grout material from one end of the injection pipe material of the support structure, checking the return of the grout material from the other end of the injection pipe material, and filling the gap between the support material and the ground with the grout material.

5. In the first step, the first support structure is erected, and the second support structure is erected immediately adjacent to the face of the tunnel space in front of the first support structure in the tunnel excavation direction, In the second step, sprayed concrete is sprayed between the first support structure and the second support structure, A tunnel construction method as described in claim 4, characterized in that in the third step, the grout material is injected from one end of the injection pipe material of the first support structure, the return of the grout material from the other end of the injection pipe material is confirmed, and the grout material is filled into the gap between the support material of the first support structure and the ground.

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