JP4760548B2 - Side-by-side tunnel structure and its construction method - Google Patents

Description

  The present invention relates to a side-by-side tunnel structure in which side portions of adjacent tunnels arranged in parallel are coupled via a center pillar and a construction method thereof.

When two adjacent tunnel main shafts are constructed adjacent to each other, the ground load is concentrated between the two tunnel main shafts, and therefore it is necessary to deal with the load. Therefore, in the past, the central advanced tunnel was excavated in advance at the center between the two tunnel main shafts, and the center pillar was installed as a shared support structure for both tunnel main shafts in the central advanced tunnel. Try to form. And after the formation of the center pillar, along the central advanced guide shaft, the advanced main shaft is excavated on one side thereof, and a support is installed on the inner periphery thereof. Is integrated with the center pillar, and after dredging, the reverse main shaft is excavated along the central advanced guide shaft to the other side. Similarly, the support work for the reverse main shaft is integrated with the center pillar. They are combined (see the following patent documents).
JP 2002-322898 A JP 2005-344318 A

  However, in the conventional construction method described above, prior to excavation of the tunnel main shaft installed in parallel, a central advanced guide shaft with a small cross section is pre-excavated in the center between both tunnel main shafts, and the interior of the narrow space is Since a common center pillar for supporting the support work of both tunnel main shafts is formed in advance, time and construction costs are spent on excavation formation of the central advanced guide shaft. In addition, the work of forming the center pillar in the narrow space of the central advanced guide shaft is very troublesome, and it takes time and cost to form the center pillar. However, there is a problem that the construction cost becomes very large as the manufacturing process becomes longer.

  The present invention has been made in view of the above circumstances. The purpose of the present invention is in a large space inside a large cross-section advanced mine and a reverse mine without excavating a central advanced guide prior to excavation of a tunnel main mine. Center pillars can be formed on the side walls located on the center side between these tunnel main shafts, respectively, to support the overload of the natural ground concentrated between the two tunnel main shafts. It is an object of the present invention to provide a side-by-side tunnel structure capable of reducing the reduction as much as possible and a construction method thereof.

  In order to achieve the above object, in the side-by-side tunnel structure according to the present invention, in the side-by-side tunnel structure in which the side portions of the tunnel main shaft are adjacent to each other, the two tunnel main shafts are arranged. The adjacent leg portions of each supporting work are split legs that split in the width direction of the tunnel, and the split base is located at the lower end of the upper half of the tunnel main tunnel, and the tunnel book below the split base A center pillar is formed by providing a reinforcing member for connecting and reinforcing a plurality of split legs integrally connected to the split base in the half-bottom half part.

  Here, the reinforcing member may be sprayed concrete. Alternatively, the reinforcing member may be a steel material that connects the split legs. Further, the reinforcing member may be a floor slab formed integrally with the invert of the main mine by connecting the lower ends of the split legs. Further, as the reinforcing member, any two or more of the sprayed concrete, the steel material, and the floor slab may be appropriately combined.

  Moreover, the natural ground in the vicinity of the center pillar may be an improved ground reinforced by a steel rod or chemical injection. Here, the improved ground is formed on the ground below the center pillar, and the improved ground is oriented in both directions of the tunnel width direction and the axial direction from both of the tunnel main walls arranged side by side. It is possible to adopt a configuration in which a large number of steel rods such as reinforcing bolts extending obliquely and entangled three-dimensionally to form a net-like body are provided. Alternatively, the improved ground is formed on a ground in the upper part of the center pillar, and the improved ground is connected to the upper half supporters of the tunnel main body arranged side by side and fastened together. The steel rods such as tie rods may be provided in parallel in the vertical direction.

In order to achieve the above object, in the method for constructing a side-by-side tunnel according to the present invention, a rearward excavation is made adjacent to a side of an advanced excavation that has been excavated in advance, and the advanced excavation is performed in parallel. In the method of constructing a side-by-side tunnel in which a center pillar is formed side by side between adjacent side walls of a pit and a reverse pit, the inner periphery of the tunnel main pit between the advanced pit and the reverse pit When the supporting work is installed along the pit, the supporting limbs on the side where the advanced mine and the reverse mine are adjacent are split in the width direction of the tunnel to form a plurality of split legs. The center pillar is formed by providing a reinforcing member that reinforces them by connecting them therebetween.

  Here, the reinforcing member may be configured to be filled with sprayed concrete between the split legs. Alternatively, the reinforcing member may be configured to install a steel material by connecting the split legs. Furthermore, the reinforcing member may be configured to form a floor slab integrally with the invert of the main mine by connecting the lower ends of the split legs. In addition, as the reinforcing member, construction of sprayed concrete between the split legs, installation of a steel material connecting the split legs, and the invert of the main mine connecting the lower ends of the split legs are integrally formed Any two or more of the installation of floor slabs to be performed may be appropriately combined.

  Further, before excavation of the reverse shaft, the ground improvement in the ground near the center pillar may be performed by performing a ground reinforcement process such as a steel rod or chemical injection. Here, the improved ground is formed in the ground below the center pillar, and the improved ground is formed in both directions of the tunnel width direction and the axial direction from both the advanced pit and the reverse resistance. A structure in which a large number of steel rods such as reinforcing bolts are placed in an oblique direction, and the large number of reinforcing bolts are entangled with each other in a three-dimensional manner and arranged in a net-like body. Alternatively, the improved ground is formed on the ground above the center pillar, and the improved ground is fastened by connecting the upper half supporters of the advanced mine and the reverse resistance installed side by side. A structure in which a plurality of steel bars such as tie rods are driven in parallel up and down can be used.

  According to the side-by-side tunnel structure and the construction method thereof according to the present invention as described above, when excavating an advanced mine and a reverse mine in parallel, a central advanced guide shaft having a small cross section is provided between the central portions thereof. Centering on the side wall on the adjacent side in the wide space of the advanced mine and the reverse mine excavated in a large cross section without performing the work process of excavating ahead and installing the center pillar in the narrow space in advance By installing a pillar, it is possible to support the overload of the natural ground concentrated between the two main tunnels, and the center pillar can be easily formed. For this reason, it is possible to shorten the construction period and reduce the construction cost as much as possible.

  In the following, a preferred embodiment of the side-by-side tunnel structure and its construction method according to the present invention will be described by taking as an example the case where two tunnels forming the upper and lower lines of the main road are provided in parallel adjacent to the earth and sand mountain. The description will be made with reference to the accompanying drawings of FIGS.

  FIG. 1 is a schematic cross-sectional view schematically showing a state where a parallel tunnel is being constructed. 2 (I) to (V) and FIGS. 3 (VI) to (IIX) are cross-sectional views taken along the lines I-I to IIX-IIX in FIG. They are shown in order.

  As shown in FIG. 1, the side-by-side tunnel 2 is provided in parallel with two tunnel main shafts that respectively define the upper and lower lines of the main road. In constructing the side-by-side tunnel 2, one tunnel main mine is advanced as an advanced mine 4, and the other tunnel main mine is moved backward while following this advanced mine 4 with a predetermined process delay. The excavation will continue as the mine 6.

  First, an advanced mine excavation process and a subsequent support installation process are sequentially performed as the first process. In the advanced mine excavation process, the advanced pit 4 is formed by excavating and slipping the face 5 using a drilling machine or the like along a predetermined tunnel installation plan line. And concrete is sequentially sprayed to the inner periphery of the excavated advanced mine 4 in order to prevent the collapse of earth and sand. After the dredging, the support 10 made of H-section steel is sequentially built and installed along the inside of the primary spray layer. This supporting work 10 is provided at a predetermined interval in the longitudinal direction of the advanced mine 4. After the support 10 is installed, the concrete is sprayed so as to fill the space between the supports 10 and 10, and the strength of the sprayed concrete layer is improved by the secondary spray layer.

  Here, as shown in (I) and (II) of FIG. 2, the construction process from excavation of the advanced mine 4 to the secondary spraying is divided into an upper half 4a and a lower half 4b of the advanced mine 4. Has been done in two stages. FIGS. 4 to 9 illustrate in detail the respective construction steps from the excavation of the upper half 4a of the advanced mine 4 to the secondary spraying, and the subsequent locking bolt placing step, which are performed in the first stage. It is. 4 to 9, (a) shows a cross section, (b) shows a plane section, and (C) shows a side section. That is, as shown in the drawing of the state before the start of forward excavation in FIG. 4 and the excavation / slipping step in FIG. 5, the upper half 4a of the advanced mine 4 is excavated first. Then, when the upper half 4a is excavated into a predetermined shape, as shown in the primary spraying step of FIG. 6, the primary spray layer 8a is formed by primarily spraying concrete on the inner peripheral surface thereof.

  When the primary spray layer 8a is formed, as shown in FIG. 7, the H-shaped steel support 10 is built along the inner peripheral surface. Here, as shown in FIG. 2 and FIG. 10, the lower half 4b to be excavated later is built into both sides of the lower half 4b of the support half 10 of the upper half 4a of the advanced mine 4 as shown in FIGS. A bracket 101 for connecting the supporting leg 102 to be mounted is provided. That is, the bracket 101 is positioned slightly above the lower half 4b of the advanced mine 4.

  Then, when the support work 10 is built in the upper half 4a of the advanced mine 4, as shown in FIG. 8, secondary spraying of concrete is performed between the support work 10 already built in advance. As a result, the secondary concrete layer 8b is formed, whereby the strength of the sprayed concrete layer 8 is improved. After the dredging, as shown in FIG. 9, if necessary, steel rods such as a number of lock bolts 12 are radiated into the natural ground through the concrete layer 8 between the support works 10 and 10 to reinforce the ground. Done. Here, the rock bolt 12 is disposed so as to avoid the planned excavation area so as not to interfere with the reverse shaft 6, but the central portion between the advanced shaft 4 and the reverse shaft 6 where the overlay load is concentrated. It is effective to reinforce the ground in the nearby ground. In this way, by consolidating the natural ground portion in the vicinity of the center between the advanced mine 4 and the reverse mine 6 as the improved ground 13, the concentration of the above-mentioned natural ground load can be reduced. The ground improvement is not essential.

  And if excavation formation of upper half part 4a of advanced mine 4 is completed through each above-mentioned construction process, excavation formation of lower half part 4b will be performed continuously. Excavation formation of this lower half part 4b is performed through excavation / slip-out construction process, primary spraying construction process, support construction building construction process, and secondary spraying construction process as well as upper half part 4a.

  By the way, the bracket 101 provided in the lower end part of the support 10 built in the upper half part 4a of the said advanced mine 4 is made into the shape branched in multiple in the width direction of the tunnel main mine. That is, in the embodiment of the illustrated example, the bracket 101 is bifurcated so as to be able to couple the two split legs 102a and 102b as the support legs 102 inside and outside the advanced mine 4 below. Thus, the split bases 101a and 101b are configured. And in the support construction installation process of the lower half part 4b of the advanced mine 4, the support work leg part 102 distribute | arranged to the center part side of the parallel tunnel 2 with which two tunnel main mines adjoin each other is built. The outer split base portion 101b branched from the bracket 101 is integrally joined to the outer split leg portion 102b extending vertically downward, and the inner split base portion 101a is slightly inward. The inner split leg 102a that curves toward is integrally coupled. On the other hand, when the support leg 102 located outside the entire side-by-side tunnel 2 is built, only the inner split leg 102a curved with respect to the split base 101a side inside the bifurcated bracket 101 is alone. Built in and combined.

  Then, when the support leg 102 is installed, a center pillar forming step is performed. That is, in this center pillar forming process, the reinforcing member 16 is integrally provided between the inner split leg 102a and the outer split leg 102b installed on the central side of the side-by-side tunnel 2 to reinforce them. Thus, the center pillar 18 is formed. Here, in the present embodiment, the reinforcing member 16 includes a steel material 161 that connects the lower ends of the inner split leg 102a and the outer split leg 102b, and spray filling between the inner split leg 102a and the outer split leg 102b. Both of the sprayed concrete 162 to be used are employed.

  When the formation of the center pillar 18 is finished, next, as shown in FIG. 1 and FIG. 2 (III), concrete is cast on the bottom surface of the advanced mine 4 to construct the advanced mine invert 20, and the advanced mine 4 Form the floor. This advanced mine invert 20 is constructed by being integrated with the lower end portion of the inner split leg 102 a provided on both sides of the support work 10. Thereby, the support work 10 and the advanced mine invert 20 including the support work leg part 102 are integrally connected in an annular shape to form a closed cross section, and the load bearing capacity is improved.

  Then, when the concrete of the advanced mine invert 20 develops strength, as shown in FIGS. 1 and 2 (IV), (V), the ground part of the side portion of the portion where the strength is developed is excavated in parallel. The excavation process of the reverse shaft 6 and the support installation process are performed. Even in the excavation process and the support installation process of the reverse mine 6, as in the case of the advanced mine 4, the upper half 6a and the lower half 6b are constructed in two stages. Each construction process of taking out, primary spraying, support construction, and secondary spraying is sequentially performed in the same procedure.

  Next, as shown in FIG. 3 (VI), concrete is cast on the bottom surface of the reverse shaft 6 to construct the reverse shaft invert 22, and the floor portion of the reverse shaft 6 is formed. This reverse mine invert 22 is constructed in exactly the same manner as the advanced mine invert. Thereby, like the case of the advanced mine 4, the support work 10 including the support work leg 102 and the reverse mine invert 22 are integrally connected in a ring shape to form a closed cross section, and the load bearing capacity is improved. After the dredging, as shown in FIG. 3 (VII), the advanced mine lining work 24 is covered with the advanced mine invert 20 so as to cover the supporting work 10 and the sprayed concrete layer 8 of the advanced mine 4 and integrally formed. Subsequently, as shown in FIG. 3 (IIX), the reverse pit cover 26 is covered with the reverse pit invert 22 so as to cover the support shaft 10 and the sprayed concrete layer 8 of the reverse pit 6 and is integrally driven. Set up.

  Therefore, when the side-by-side tunnels 2 adjacent to each other in the side wall portions of the tunnel main pits arranged in parallel are constructed as described above, when excavating the advanced mine 4 and the reverse mine 6 side by side, Advanced mine 4 and reverse mine 6 excavated in a large cross section without excavating a central advanced guide shaft with a small cross section between the central portions and performing a work process of installing a center pillar in the narrow space in advance. Center pillars 18 and 18 are respectively installed on adjacent side wall portions in a large space of the tunnel, so that it is possible to support the overload of the natural ground concentrated between the two main tunnels. 18 can be easily formed. For this reason, not only can the construction period of the side-by-side tunnel 2 be shortened as much as possible, but also the construction cost can be reduced as much as possible.

  FIG. 11 shows a reinforcing member 16 of the split legs 102a and 102b constituting the center pillar 18, and a floor slab 163 is installed integrally with the inverts 20 and 22 of the tunnel main shaft by connecting the lower ends of the split legs 102a and 102b. An example is shown. In this case, the floor slab 163 is performed simultaneously with the construction of the inverts 20 and 22. Then, both the inner split leg 102a and the outer split leg 102b extend downward, and their extended ends are joined by the steel material 161 and embedded in the floor slab 163. Moreover, it is preferable that the inner split leg 102a has a larger curvature on the lower end side so as to follow the outer shape of the inverts 20 and 22. By providing such a floor slab 163 as the reinforcing member 16, not only can the strength of the center pillar 18 be further increased, but also the load applied to the center pillar 18 can be smoothly transmitted to the inverts 20 and 22. The load concentration on the natural ground in the lower part of the pillar 18 can be reduced. Further, as the reinforcing member 16, filling concrete 162 between the split legs 102a and 102b is filled, a steel material 161 connecting the split legs 102a and 102b, and the lower ends of the split legs 102a and 102b. Any two or more of the installation of the floor slab 163 integrally formed with the inverts 20 and 22 of the main mine may be combined as appropriate.

  FIG. 12 shows an example in which a ground reinforcement process is applied to a natural ground below the center pillar 18 formed between the central portions of the side-by-side tunnels 2 to form an improved ground 13. As shown in the figure, this improved ground 13 is formed by placing a large number of steel bars such as reinforcing bolts 12A. The reinforcement bolts 12A are driven from both the advanced mine 4 side and the reverse mine 6 side which are arranged side by side. Here, each reinforcement bolt 12A driven from the advanced mine 4 and the reverse resistance 6 is directed obliquely downward and is also obliquely oriented in the tunnel axis direction, and is arranged in the tunnel width direction and the axial direction. Are crossed with each other in two directions. That is, as a result, a large number of the reinforcing bolts 12A are formed into a mesh body that crosses and entangles with each other three-dimensionally, and ground reinforcement is performed by the mesh body.

  In other words, this improved ground 13 extends obliquely from both the advanced tunnel 4 and the reverse resistance 6 which are the tunnel main walls arranged side by side in the tunnel width direction and the axial direction, respectively. Steel rods such as a number of reinforcing bolts 12A that are intertwined three-dimensionally to form a net-like body are provided. Further, if necessary, the reinforcing bolt 12A may be made of a hollow tube, and by using this, a chemical solution may be further injected into the ground to improve the ground.

  FIG. 13 shows the vicinity of the center peeler 18 located above the central portion between the reverse shaft 6 and the advanced shaft 4 at the end of the excavation formation process of the upper half 6a of the reverse shaft 6 shown in FIG. This shows an example in which ground reinforcement is applied to a natural ground. In this ground reinforcement, a plurality of steel rods such as tie rods 12B are vertically aligned in parallel so as to connect the support members 10 of the upper half portions 4a, 6a of the advanced mine 4 and the reverse mine 6 arranged side by side. The improved ground 13 is formed by placing and fastening.

  That is, the improved ground 13 has steel rods such as a plurality of tie rods for connecting and fixing the upper half supporters of the advanced tunnel 4 and the reverse drag 6 which are tunnel main walls arranged side by side. It is provided in parallel up and down. Even in this case, if necessary, the tie rod 12B is made of a hollow tube, and by using this, a chemical solution is further injected into the ground to improve the ground. good.

  In this way, the ground pile in the vicinity of the upper part and the lower part of the center pillar 18 is reinforced to improve the ground, and the earth bearing strength is increased, so that the load on the center pillar is concentrated on the center pillar 18 part and the center pillar. Land subsidence below 18 parts can be suppressed.

  In the illustrated embodiment, the case where two parallel tunnel main shafts are constructed adjacent to each other is illustrated. However, the present invention is not limited to this, and three or more tunnel cores are provided in parallel. The present invention can also be applied to a case where they are built adjacent to each other.

It is a schematic plane sectional view which shows roughly the construction middle state of the parallel tunnel which concerns on this invention. FIGS. (I) to (V) are cross-sectional views taken along lines I-I to V-V in FIG. FIGS. (VI) to (IIX) are sectional views taken along arrows VI-VI to IIX-IIX in FIG. The state before a forward excavation of an advanced mine is shown, (a) is a cross-sectional view, (b) is a plane cross-sectional view, and (C) is a side cross-sectional view. The excavation / slipping process of the upper half of the advanced mine is shown, (a) is a cross-sectional view, (b) is a plane cross-sectional view, and (C) is a side cross-sectional view. The primary spraying process of the upper half of an advanced mine is shown, (a) is a cross-sectional view, (b) is a plane cross-sectional view, and (C) is a side cross-sectional view. The steel support construction process of an upper half part of an advanced mine is shown, (a) is a cross-sectional view, (b) is a plane cross-sectional view, and (C) is a side cross-sectional view. The secondary spraying process of an upper half of an advanced mine is shown, (a) is a cross-sectional view, (b) is a plane cross-sectional view, and (C) is a side cross-sectional view. FIG. 2A shows a process for placing a rock bolt in the upper half of an advanced mine, wherein FIG. 3A is a cross-sectional view, FIG. 2B is a cross-sectional view, and FIG. It is an enlarged view of the A section shown in FIG. It is an enlarged view of the site | part corresponding to FIG. 10, and is a figure which shows the modification at the time of providing a floor slab as a reinforcement member. It is an enlarged view of the part corresponding to FIG. 10, and is a figure which shows the modification at the time of performing ground improvement to the natural ground of the center pillar lower part. It is a figure which shows the modification at the time of giving ground improvement to the natural ground above the center part between an advanced mine and a reverse mine.

Explanation of symbols

2 Side-by-side tunnel 4 Advanced mine 4a Upper half 4b Lower half 6 Reverse mine 6a Upper half 6b Lower half 8 Sprayed concrete layer 8a Primary spray layer 8b Secondary spray layer 10 Supporting work 101 Bracket 101a Splitting base inside 101b Outer split base 102 Support leg 102a Inner split leg 102b Outer split leg 12 Rock bolt 16 Reinforcement member 161 Steel material 162 Shotcrete 163 Floor slab 18 Center pillar 20 Advanced mine invert 22 Reverse mine invert 24 Advanced mine lining 26 Reverse mine lining

Claims (14)

It is a side-by-side tunnel structure in which the sides of the tunnel main shaft are adjacent to each other,
The legs on the sides adjacent to each of the supporting works arranged in both tunnel main shafts are split legs that split in the width direction of the tunnel,
The split base is positioned at the lower end of the upper half of the tunnel main shaft, and the lower half of the tunnel main shaft below the split base is disposed between a plurality of split legs integrally connected to the split base. A side-by-side tunnel structure, wherein a center pillar is formed by providing a reinforcing member that is coupled and reinforced.   The parallel tunnel structure according to claim 1, wherein the reinforcing member is sprayed concrete.   The side-by-side tunnel structure according to claim 1, wherein the reinforcing member is a steel material that connects the split legs.   The side-by-side tunnel structure according to any one of claims 1 to 3, wherein the reinforcing member is a floor slab formed integrally with an invert of a main pit by connecting lower ends of the split legs.   The side-by-side tunnel structure according to any one of claims 1 to 4, wherein a natural ground in the vicinity of the center pillar is an improved ground reinforced by a steel rod, chemical injection, or the like.   The improved ground is formed in a natural ground below the center pillar, and the improved ground extends obliquely in both directions of the tunnel width direction and the axial direction from both of the tunnel main walls arranged side by side. 6. The side-by-side tunnel structure according to claim 5, wherein a plurality of steel rods such as reinforcing bolts that are three-dimensionally entangled with each other to form a net-like body are provided.   The improved ground is formed in a natural ground above the center pillar, and a plurality of tie rods and the like for connecting and fixing the upper half supporters in the tunnel main wall arranged in parallel to the improved ground, etc. The parallel tunnel structure according to claim 5, wherein the steel rods are provided in parallel in the vertical direction. Adjacent to the side of the advanced mine where the excavation was carried out, the backward mine was laid in parallel, and the tunnel main mine was built side by side by forming a center pillar between adjacent sides of the advanced mine and the reverse mine. A method for constructing a side-by-side tunnel,
When installing a support along the inner circumference of the tunnel main pit between the advanced mine and the reverse mine, split the support legs on the side where the advanced mine and the reverse mine are adjacent in the width direction of the tunnel. To form multiple split legs,
A method for constructing a side-by-side tunnel, wherein a center pillar is formed by providing a reinforcing member for connecting and reinforcing these split legs between the split legs.   The construction method for a side-by-side tunnel according to claim 8, wherein the reinforcing member is constructed by filling sprayed concrete between the split legs.   The method for constructing a side-by-side tunnel according to claim 8, wherein a steel material is installed as the reinforcing member so as to connect the split legs.   The method for constructing a side-by-side tunnel according to any one of claims 8 to 10, wherein a floor slab is installed as the reinforcing member integrally with an invert of a main mine by connecting lower ends of the split legs. .   Before excavation of the reverse shaft, the ground improvement in the ground near the center pillar is performed by performing ground reinforcement by a steel rod, chemical injection, or the like. The method for constructing the parallel tunnel as described.   The improved ground is formed in the ground below the center pillar, and the improved ground is oriented obliquely in two directions, the tunnel width direction and the axial direction, from both the advanced pit and the rearward resistance. The steel rods such as a large number of reinforcing bolts are placed, and the large number of reinforcing bolts are three-dimensionally entangled with each other and arranged in a net-like body. How to build a side-by-side tunnel. The improved ground is formed in a natural ground above the center pillar, and the improved ground is connected to the upper half supporters of the advanced mine and the reverse resistance arranged side by side, and is fastened and fixed. 14. The method for constructing a side-by-side tunnel according to claim 12 or 13, wherein steel rods such as tie rods are formed by vertically driving in parallel.

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