JP7345409B2 - How to construct a tunnel support structure - Google Patents

Description

The present invention relates to a method of constructing a supporting structure for a tunnel.

When constructing a mountain tunnel using the NATM (New Austrian Tunneling Method) method, etc., the tunnel walls are supported with steel members and shotcrete to stabilize the tunnel. The ground has a characteristic that the ground pressure decreases as the shaft wall of the tunnel excavation is displaced so as to reduce the size of the tunnel. Disclosed is a support structure capable of supporting the wall of a tunnel excavation shaft in a state where the support structure is lowered.

In the support structure disclosed in Patent Document 1, the easily compressible deformable portion is provided adjacent to the steel member and the shotcrete in the circumferential direction of the tunnel. The easily compressible deformable part is a hollow shell such as hollow glass particles or a concrete member containing air bubbles with a volume ratio of 10% or more. When earth pressure acts on the support structure, the easily compressible deformable part deforms so as to collapse, and the wall of the tunnel excavation is displaced along with the steel members and shotcrete, causing the earth pressure to decrease. After the deformation of the compressively deformable part has subsided, the compressively deformable part exhibits the required load-bearing performance, and the wall of the tunnel excavation can be constructed in cooperation with steel members and shotcrete under reduced ground pressure. Work and support.

JP 2018-155048 Publication

In the support structure disclosed in Patent Document 1, the inner wall of the tunnel excavation shaft is displaced until the hollow shell or bubble in the easily compressible deformable part collapses and the deformation of the easily compressible deformable part naturally converges. Therefore, the wall of the tunnel excavation shaft may be displaced more than necessary, and the cross section of the tunnel may become smaller than the designed cross section. In this case, it is necessary to remove the constructed support structure, excavate the inner wall of the tunnel excavation shaft, and re-build the support structure, which makes it impossible to construct the tunnel efficiently.

The present invention aims to efficiently construct tunnels.

The present invention is a method for constructing a tunnel support structure, and the tunnel support structure includes a plurality of steel members provided along a tunnel excavation wall at predetermined intervals in the tunnel axial direction, and adjacent steel members. The construction method includes a concrete structure provided between the concrete structure and an easily compressible deformable member that can be compressively deformed more easily than steel members. A steel member installation process in which compressive deformable members are installed along the tunnel excavation wall at intervals of A concrete structure installation step for providing a structure; and a deformation suppression step for suppressing deformation of the easily compressible member during the deformation process of the easily compressible member. It has a gap that narrows as it deforms, and because of the presence of this gap, the stiffness of the easily compressible deformable member is lower than that of steel members and concrete structures.In the deformation suppression process, cement-based By filling the hardening material, deformation of the compressively deformable member is suppressed.
The present invention also provides a method for constructing a tunnel support structure, which includes a plurality of steel members provided at predetermined intervals in the tunnel axis direction along a tunnel excavation wall, and adjacent steel members. It is equipped with a concrete structure installed between the steel members and a member that is easily compressible and deformable than steel members, and the construction method is to move the steel members from the already installed steel members in the tunnel axis A steel member installation process in which compressive deformable members are provided along the tunnel excavation wall at predetermined intervals and adjacent to the steel members in the circumferential direction of the tunnel, and between steel members adjacent in the tunnel axial direction. A concrete structure installation step in which a concrete structure is installed in the steel member, and a deformation suppression step in which deformation of the easily compressible member is suppressed during the deformation process of the easily compressible member. A plurality of easily compressible deformable members are provided at predetermined intervals in the tunnel circumferential direction, and a compressively deformable member is provided between adjacent steel members in the tunnel circumferential direction, and in the deformation suppression process, steel members are placed across the compressively deformable members in the tunnel circumferential direction. At the same time, by connecting it to the steel member, deformation of the easily compressible deformable member is suppressed.
The present invention also provides a method for constructing a tunnel support structure, which includes a plurality of steel members provided at predetermined intervals in the tunnel axis direction along a tunnel excavation wall, and adjacent steel members. It is equipped with a concrete structure installed between the steel members and a member that is easily compressible and deformable than steel members, and the construction method is to move the steel members from the already installed steel members in the tunnel axis A steel member installation process in which compressive deformable members are provided along the tunnel excavation wall at predetermined intervals and adjacent to the steel members in the circumferential direction of the tunnel, and between steel members adjacent in the tunnel axial direction. A concrete structure installation process in which a concrete structure is installed in the concrete structure, and a deformation suppression process in which deformation of the easily compressible deformable member is suppressed during the deformation process of the easily compressible deformable member, and after the concrete structure installation process, the tunnel excavation shaft is After excavation, a deformation prevention process is performed.

The present invention also provides a method for constructing a tunnel support structure, which includes a plurality of steel members provided at predetermined intervals in the tunnel axis direction along a tunnel excavation wall, and adjacent steel members. It is equipped with a concrete structure installed between steel members, and members that are easily compressible and deformable than the concrete structure, and the construction method is as follows: The steel members are installed along the walls of the tunnel excavation at predetermined intervals, the concrete structure is provided between adjacent steel members in the tunnel axis direction, and the easily compressible deformable members are attached to the concrete structure around the tunnel periphery. A concrete structure installation step that is provided adjacent to the direction of the compressive deformable member; and a deformation suppressing step that suppresses deformation of the easily compressible deformable member during the deformation process of the easily compressible deformable member. has a gap that narrows as it is compressively deformed, and because of the existence of this gap, the rigidity of the easily compressible deformable member is lower than that of steel members and concrete structures. By filling the cement-based hardening material, deformation of the easily compressible deformable member is suppressed.
The present invention also provides a method for constructing a tunnel support structure, which includes a plurality of steel members provided at predetermined intervals in the tunnel axis direction along a tunnel excavation wall, and adjacent steel members. It is equipped with a concrete structure installed between steel members, and members that are easily compressible and deformable than the concrete structure, and the construction method is as follows: The steel members are installed along the walls of the tunnel excavation at predetermined intervals, the concrete structure is provided between adjacent steel members in the tunnel axis direction, and the easily compressible deformable members are attached to the concrete structure around the tunnel periphery. The concrete structure installation step includes a concrete structure installation step that is provided adjacent to the direction, and a deformation suppression step that suppresses deformation of the easily compressible deformable member during the deformation process of the easily compressible deformable member. A plurality of members are provided at predetermined intervals in the circumferential direction of the tunnel, and a member that is easily deformed by compression is provided between adjacent concrete structures in the circumferential direction of the tunnel, and in the deformation suppression process, steel materials are placed across the members that are easily deformed by compression in the circumferential direction of the tunnel. At the same time, by connecting it to the concrete structure, deformation of the compressively deformable member is suppressed.
The present invention also provides a method for constructing a tunnel support structure, which includes a plurality of steel members provided at predetermined intervals in the tunnel axis direction along a tunnel excavation wall, and adjacent steel members. It is equipped with a concrete structure installed between steel members, and members that are easily compressible and deformable than the concrete structure, and the construction method is as follows: The steel members are installed along the walls of the tunnel excavation at predetermined intervals, the concrete structure is provided between adjacent steel members in the tunnel axis direction, and the easily compressible deformable members are attached to the concrete structure around the tunnel periphery. A concrete structure installation process is provided adjacent to the direction of the concrete structure, and a deformation suppressing process for suppressing deformation of the easily compressible deformable member during the deformation process of the easily compressible deformable member, and after the concrete structure installation process, the tunnel excavation shaft is After excavation, a deformation prevention process is performed.

According to the present invention, a tunnel can be efficiently constructed.

3 is a cross-sectional view of a tunnel support structure according to an embodiment of the present invention, showing a cross section taken along line II in FIG. 2. FIG. 2 is a sectional view of a tunnel support structure according to an embodiment of the present invention, in which (a) shows a cross section taken along line IIA-IIA in FIG. 1, and (b) shows a cross section taken along line IIB-IIB in FIG. 1. show. FIG. 3 is a diagram for explaining the ground pressure characteristics of the ground. (a) is a sectional view schematically showing the easily compressible deformable member before compressive deformation occurs, and (b) is a sectional view schematically showing the easily compressible deformable member in the process of compressive deformation; c) is a cross-sectional view schematically showing the easily compressible deformable member in a state where the compressive deformation has converged, and (d) is a diagram showing the strength characteristics of the easily compressible deformable member. (a) is a front view of a modified example of the easily compressible deformable member, and (b) is a front view of yet another modified example of the easily compressible deformable member. (a) is an enlarged view of the VIA section shown in FIG. 1, and (b) is a diagram showing the strength characteristics of the steel shoring in which deformation of the compressively deformable member is suppressed during the deformation process. FIG. 2 is a diagram for explaining a method for constructing a tunnel support structure according to an embodiment of the present invention. FIG. 3 is a diagram for explaining displacement of a tunnel excavation wall, deformation of a steel shoring, pressure of the ground, and stress in the steel shoring. It is a sectional view of the tunnel support structure concerning the 1st modification of the embodiment in the present invention. It is a sectional view of the tunnel support structure concerning the 2nd modification of the embodiment in the present invention. It is a sectional view of the tunnel support structure concerning the 3rd modification of the embodiment in the present invention.

Hereinafter, a tunnel support structure 100 and a method for constructing the tunnel support structure 100 according to an embodiment of the present invention will be described with reference to the drawings.

The tunnel support structure 100 is constructed during tunnel excavation work using the NATM construction method. In the NATM construction method, the tunnel T is constructed in the axial direction by repeating the blasting process, shedding process, and support structure construction process every predetermined distance (for example, 1 to 3 m). In the support structure construction process, as shown in FIGS. 1 and 2, a tunnel support structure 100 is constructed in the tunnel excavation to support the tunnel excavation wall (hereinafter also simply referred to as "pit wall") W. Stabilize Tunnel T.

Hereinafter, the direction along the central axis of the tunnel T will be referred to as the "tunnel axial direction", the direction around the central axis of the tunnel T will be referred to as the "tunnel circumferential direction", and the radial direction centered on the central axis of the tunnel T will be referred to as "the tunnel axial direction". tunnel radial direction.

The ground has a characteristic that the ground pressure decreases as the tunnel wall W is displaced in the direction in which the tunnel excavation shaft shrinks. The ground pressure characteristics of the ground will be explained with reference to FIGS. 3(a) and 3(b). FIG. 3(a) is a cross-sectional view of the rock where excavation has been completed up to point A. In FIG. 3(a), illustration of the tunnel support structure 100 is omitted. FIG. 3(b) is a diagram showing the pressure characteristics of the ground at point A. The horizontal axis represents the displacement ΔW of the mine wall W at point A, and the vertical axis represents the ground pressure P at point A.

When the excavation of the earth is completed up to point A, there is almost no displacement ΔW of the mine wall W at point A, and the ground pressure P at point A is P1, which is approximately equal to the ground pressure in the unexcavated state. The displacement ΔW of the tunnel wall W at point A is induced and increases as the tunnel excavation progresses. Specifically, when the excavation of the earth is completed to point B, the displacement ΔW of the mine wall W at point A becomes larger than when the excavation of the earth is completed to point A. At this time, the ground pressure P at point A decreases to P2, which is smaller than P1, with the displacement of the mine wall W.

When the tunnel excavation shaft is further excavated and the excavation of the ground is completed to point C, the displacement ΔW of the tunnel wall W at point A becomes larger compared to the time when the excavation of the ground is completed to point B. At this time, the ground pressure P at point A decreases to P3, which is smaller than P2, with the displacement of the mine wall W. Similarly, when the excavation of the earth is completed to point D, the displacement ΔW of the mine wall W at point A becomes larger than when the excavation of the earth is completed to point C. At this time, the ground pressure P at point A decreases to P4, which is smaller than P3.

In this way, the tunnel wall W is displaced as the tunnel excavation shaft progresses, and the ground pressure P of the ground decreases as the tunnel wall W is displaced.

The tunnel support structure 100 supports the tunnel wall W by utilizing this characteristic of the earth. Specifically, the tunnel support structure 100 has the configuration shown below to support the shaft wall W while allowing displacement of the shaft wall W to some extent and reducing ground pressure. Therefore, compared to the case where the tunnel wall W is supported without reducing the ground pressure, the load that the tunnel support structure 100 receives can be reduced, and the stability of the tunnel T can be improved.

As shown in FIGS. 1 and 2, the tunnel support structure 100 includes a plurality of steel members 10 provided along the tunnel wall W at predetermined intervals in the tunnel axial direction, and It includes a concrete structure 20 provided between steel members 10 adjacent in the axial direction, and an easily compressible deformable member 30 that is easier to compress and deform than the steel members 10 and the concrete structure 20.

The steel member 10 is, for example, an H-shaped steel, and extends in the circumferential direction of the tunnel. A plurality of steel members 10 are provided at predetermined intervals in the circumferential direction of the tunnel, and an easily compressible deformable member 30 is provided between adjacent steel members 10 in the circumferential direction of the tunnel. Further, the steel member 10 is provided in the circumferential direction of the tunnel, with the easily compressible deformable member 30 interposed in a part thereof. In other words, the easily compressible deformable member 30 is provided adjacently between adjacent steel members 10 .

The concrete structure 20 is shotcrete formed by spraying concrete material onto the pit wall W. The concrete material may be a cementitious hardening material, such as submersible concrete, high fluidity concrete or mortar.

Similar to the steel member 10, a plurality of concrete structures 20 are provided at predetermined intervals in the circumferential direction of the tunnel. Compressively deformable members 30 are provided between concrete structures 20 adjacent to each other in the tunnel circumferential direction. Moreover, the concrete structure 20 is provided in the circumferential direction of the tunnel, and the compressive deformation easily-deformable member 30 is provided in a part thereof. That is, the compressible deformable member 30 is provided adjacent to the concrete structure 20. Note that a plurality of compressible deformable members 30 are arranged in the tunnel axial direction.

Here, with reference to FIG. 4, the structure and strength characteristics of the compressively deformable member 30 will be described.

FIGS. 4(a) to 4(c) are cross-sectional views schematically showing the compressively deformable member 30. FIG. 4(a) shows a state before compressive deformation occurs, FIG. 4(b) shows a state in the compressive deformation process, and FIG. 4(c) shows a state after compressive deformation has converged.

As shown in FIGS. 4(a) to 4(c), the compression-deformable member 30 is a so-called jack, and includes a cylinder case 31, a piston 32, a rod 33, and a receiving plate . The cylinder case 31, the piston 32, the rod 33, and the receiving plate 34 are made of steel.

The piston 32 is slidably housed in the cylinder case 31, and divides the inside of the cylinder case 31 into a pair of fluid chambers 35a and 35b. The rod 33 has one end connected to the piston 32 and extends from the cylinder case 31. A receiving plate 34 is connected to the other end of the rod 33. When the piston 32 slides in the direction to contract the fluid chamber 35a, the rod 33 enters the cylinder case 31, and the easily compressible deformable member 30 is compressed. A gap is formed between the cylinder case 31 and the receiving plate 34 in the state before compressive deformation (FIG. 4(a)) and in the state in the compressive deformation process (FIG. 4(b)).

The compression-deformable member 30 is arranged between adjacent steel members 10 in the tunnel circumferential direction or between concrete structures 20 adjacent in the tunnel circumferential direction so that the compression direction of the compression-deformable member 30 substantially coincides with the tunnel circumferential direction. placed between. Therefore, the ground pressure of the ground acts in a direction that compresses the compression-deformable member 30 (in the direction of the white arrow shown in FIG. 4(b)).

A port 36a communicating with the fluid chamber 35a and a port 36b communicating with the fluid chamber 35b are formed in the cylinder case 31. Ports 36a and 36b are connected to an accumulator (not shown) via a control valve (not shown). The control valve and the accumulator discharge fluid from the fluid chamber 35a and supply fluid to the fluid chamber 35b when the compression-deformable member 30 receives a predetermined load in the compression direction, thereby reducing the pressure in the fluid chamber 35a and the fluid chamber 35b. It operates to keep it approximately constant. The fluid is, for example, air. The strength characteristics of the compressively deformable member 30 will be described in detail with reference to FIG. 4(d).

FIG. 4(d) is a diagram showing the strength characteristics of the compressively deformable member 30 when a load is applied in the direction of the white arrow shown in FIG. 4(b). The horizontal axis represents the displacement ΔM (deformation amount of the easily compressible deformable member 30) of the receiving plate 34 with respect to the cylinder case 31, and the vertical axis represents the load L applied to the easily compressible deformable member 30. In FIG. 4(d), the strength characteristics of the steel member 10 are also shown. The strength characteristics of the concrete structure 20 are substantially the same as the strength characteristics of the steel member 10, so illustration thereof is omitted.

In FIG. 4(d), ΔM1 is larger than 0 (zero), and ΔM2 is larger than ΔM1 (0<ΔM1<ΔM2). Further, L1 is larger than 0 (zero), and L2 is larger than L1 (0<L1<L2). L2 corresponds to the load capacity of the steel member 10 and the concrete structure 20.

As shown in FIG. 4(d), in a range less than ΔM1, the load L on the compressively deformable member 30 increases to L1 as the displacement ΔM increases. This is because, as shown in FIG. 4(a), fluid cannot flow into or out of the fluid chambers 35a and 35b, and the piston 32, rod 33, and receiving plate 34 are displaced due to compression of the fluid in the fluid chambers 35a. This is a permissible state.

In the range from ΔM1 to ΔM2, the load L on the compressively deformable member 30 remains L1 even if the displacement ΔM increases. This is achieved by discharging fluid from the fluid chamber 35a and supplying fluid to the fluid chamber 35b so as to keep the pressures in the fluid chambers 35a and 35b substantially constant, thereby changing the displacement of the piston 32, rod 33, and receiving plate 34. It is in a state where it is allowed. The state in which the displacement ΔM reaches ΔM2 corresponds to a state in which the volume of the fluid chamber 35a becomes the minimum and the compressive deformation of the easily compressible deformable member 30 converges naturally, as shown in FIG. 4(c).

In a range exceeding ΔM2, the load L on the compressively deformable member 30 increases to L1 as the displacement ΔM increases. This is a state in which the cylinder case 31 and the rod 33 are compressively deformed and the receiving plate 34 is displaced.

In this way, in the compressively deformable member 30, a gap is formed between the cylinder case 31 and the receiving plate 34 during the compressively deforming process, and compared to the steel member 10 and the concrete structure 20, Rigidity per unit cross section is small. Therefore, the compressively deformable member 30 is easier to compressively deform than the steel member 10 and the concrete structure 20.

The compression-deformable member 30 is not limited to the jack shown in FIG. 4(a). The members shown in FIGS. 5(a) and 5(b) may be used as the compressively deformable member 30.

In the example shown in FIG. 5(a), the compression deformation easily member 30 includes a pair of receiving plates 131 that are arranged substantially parallel to each other with an interval, and a cylindrical portion 132 that is arranged between the pair of receiving plates 131. It has . The cylindrical portion 132 is arranged such that its central axis runs along the pair of receiving plates 131 . A plurality of rod portions 133 are provided on the outer periphery of the cylindrical portion 132 along the central axis of the cylindrical portion 132, and the cylindrical portion 132 is connected to the receiving plate 131 via the rod portions 133. . A gap is formed between the pair of receiving plates 131 by the cylindrical portion 132 , and as the cylindrical portion 132 plastically deforms and collapses, the compressively deformable member 30 is more easily compressed than the steel member 10 and the concrete structure 20 . Easily compressed and deformed.

In the example shown in FIG. 5(b), the compressible deformation easily member 30 includes a pair of receiving plates 231 arranged approximately parallel to each other with an interval, and a pair of supporting plates 232 provided across the pair of receiving plates 231. It has . A gap is formed between the pair of support plates 231 by the pair of support plates 232, and when the pair of support plates 232 are plastically deformed and crushed, the easily compressible deformable member 30 is attached to the steel member 10 and the concrete structure 23. It compresses and deforms more easily.

The strength characteristics of the compressively deformable member 30 shown in FIGS. 5(a) and 5(b) also have the strength characteristics shown in FIG. 4(d).

If the displacement of the tunnel wall W is allowed until the deformation of the compressively deformable member 30 naturally converges, the tunnel wall W may be displaced more than necessary, and the cross section of the tunnel T may become smaller than the designed cross section. If the cross section of the tunnel T becomes smaller than the designed cross section, so-called backstitching becomes necessary, and the tunnel T cannot be constructed efficiently.

As shown in FIG. 6(a), the tunnel support structure 100 includes a deformation suppressing portion 40 that suppresses deformation of the easily compressible deformable member 30 during the deformation process of the easily compressible deformable member 30. Therefore, the compressively deformable member 30 exhibits a predetermined rigidity when deformation is suppressed, and supports the mine wall W in cooperation with the steel member 10 or the concrete structure 20. Therefore, the displacement of the shaft wall W can be reduced compared to the case where the shaft wall W is displaced until the deformation of the compressively deformable member 30 naturally converges. Thereby, so-called backstitching can be reduced, and the tunnel T can be constructed efficiently.

In the following, a structure constituted by a plurality of steel members 10 provided at predetermined intervals in the circumferential direction of a tunnel, and easily compressible deformable members 30 provided between adjacent steel members 10 in the circumferential direction of the tunnel. Also called "steel shoring". Further, a structure constituted by a plurality of concrete structures 20 provided at predetermined intervals in the circumferential direction of the tunnel, and easily compressible deformation members 30 provided between the concrete structures 20 adjacent to each other in the circumferential direction of the tunnel. Also called "concrete shoring". Structures in which the deformation of the easily compressible deformable member 30 is suppressed by the deformation suppressing portion 40 are also referred to as "steel shoring" and "concrete shoring."

The effect of the deformation suppressing section 40 will be explained in more detail with reference to FIG. 6(b). FIG. 6(b) is a diagram showing the strength characteristics of a steel shoring structure in which deformation of the compressively deformable member 30 is suppressed during the deformation process. In FIG. 6(b), an example of the ground pressure characteristics of the ground is also shown. The strength characteristics of concrete shoring are approximately the same as those of steel shoring, so illustration thereof is omitted.

As shown in FIG. 6(b), if the deformation of the compressively deformable member 30 is not suppressed during the deformation process (indicated by the broken line), the pit wall W will be affected by the stress in the steel shoring and the ground pressure P. It is displaced until it reaches balance ΔW1. When the deformation of the compressively deformable member 30 is suppressed during the deformation process (as shown by the solid line), the pit wall W is displaced to ΔW2 where the stress in the steel shoring and the ground pressure P are balanced. ΔW2 becomes smaller than ΔW1. Therefore, the displacement of the pit wall W can be reduced by the difference between ΔW1 and ΔW2.

The deformation suppressing portion 40 is a concrete material that is filled between the cylinder case 31 and the receiving plate 34 of the easily compressible deformable member 30 and solidified. As the concrete material, similarly to the concrete structure 20, a cement-based hardening material can be used, and specifically, underwater inseparable concrete, high fluidity concrete, or mortar can be used. As the deformation suppressing portion 40, epoxy resin may be used instead of concrete material.

Next, a method for constructing the tunnel support structure 100 will be described with reference to FIGS. 7 and 8. FIGS. 7(a) and 7(b) show a state in which excavation has been completed up to point A. FIG. 7(c) shows a state in which the ground has been further excavated from point A.

In the method for constructing the tunnel support structure 100, first, as shown in FIG. component installation process). The steel member installation step is performed after excavating the ground and digging a tunnel a predetermined length (for example, 1 to 3 m), and the steel member 10 is installed near the face. In the steel member installation process, a plurality of steel members 10 are provided at predetermined intervals in the circumferential direction of the tunnel, and the easily compressible deformable members 30 are provided between adjacent steel members 10 in the circumferential direction of the tunnel.

Next, as shown in FIG. 7(b), a concrete structure 20 is installed in the tunnel excavation by spraying and hardening concrete material between the steel members 10 adjacent in the tunnel axis direction (concrete structure installation process). In the concrete structure installation process, a plurality of concrete structures 20 are provided at predetermined intervals in the tunnel circumferential direction, and compressive deformation easily members 30 are provided between adjacent concrete structures 20 in the tunnel circumferential direction.

In the concrete structure installation process, the easily compressible deformable member 30 may be installed adjacent to the concrete structure 20 after spraying the concrete material, or the easily compressible deformable member 30 may be installed in the tunnel excavation and then the concrete material is installed. May be sprayed. When spraying concrete material after the easily compressible deformable member 30 is installed in a tunnel excavation, the easily compressible deformable member 30 is cured with a sheet or the like so that the concrete material is not sprayed onto the easily compressible deformable member 30. It is preferable to leave it there.

FIG. 8(a) is a diagram showing the pressure characteristics of the ground at point A and the strength characteristics of the steel shoring. In the states shown in FIGS. 7(a) and (b), the ground has been excavated up to point A, so there is almost no displacement ΔW of the mine wall W, and the ground pressure P at point A is the same as in the state where it is not excavated. P1 is approximately equal to the ground pressure at . Since there is almost no displacement ΔW of the pit wall W, almost no deformation of the steel shoring occurs.

Next, as shown in FIG. 7(c), a tunnel is dug. As the tunnel excavation progresses, displacement of the tunnel wall W is induced and increases. With the displacement of the pit wall W, the steel shoring is deformed.

Specifically, as shown in FIG. 8(a), when excavation to point B (see FIG. 3) is completed, the displacement ΔW of the mine wall W becomes ΔW3. The steel shoring is deformed by ΔW3 due to the displacement of the pit wall W. When the tunnel excavation shaft is further excavated to a point C (see FIG. 3), the displacement ΔW of the tunnel wall W becomes ΔW4, which is larger than ΔW3. The steel shoring is deformed by ΔW4 due to the displacement of the pit wall W.

Thereafter, in the deformation process of the compressively deformable member 30, the deformation of the compressively deformable member 30 is suppressed (deformation inhibiting step). Specifically, the deformation suppressing portion 40 is formed by spraying concrete material into the gap between the easily compressible deformable member 30.

It is preferable that the deformation suppression step is performed after the ground pressure has decreased until the displacement of the mine wall W can be stopped by the rigidity of the steel member 10 and the concrete structure 20. For example, if it is determined that the displacement of the pit wall W can be stopped due to the rigidity of the steel member 10 at point A when excavation to point C (see Fig. 3) is completed, the deformation suppression step is carried out after that point. Let's do it. As a result, the strength characteristics of the steel shoring become the strength characteristics shown in FIG. 8(b).

After the deformation suppression process, when the tunnel excavation shaft is further excavated, the stress in the steel support and the ground pressure P are balanced. Therefore, the displacement of the pit wall W stops. Therefore, the displacement of the shaft wall W can be reduced compared to the case where the shaft wall W is displaced until the deformation of the compressively deformable member 30 naturally converges. Thereby, so-called backstitching can be reduced, and the tunnel T can be constructed efficiently.

The tunnel support structure 100 is constructed over the entire length of the tunnel T by repeatedly performing the steel member installation process, the concrete structure installation process, and the deformation suppression process.

According to the above embodiment, the following effects are achieved.

In the tunnel support structure 100 and its construction method, deformation of the easily compressible deformable member 30 is suppressed during the deformation process of the easily compressible deformable member 30. Therefore, the compressively deformable member 30 exhibits a predetermined rigidity when deformation is suppressed, and supports the pit wall W in cooperation with the steel member 10 and the concrete structure 20. Therefore, it is possible to prevent the tunnel wall W from being displaced more than necessary, and it is possible to prevent the cross section of the tunnel T from becoming smaller than the designed cross section. Thereby, so-called backstitching can be reduced, and the tunnel T can be constructed efficiently.

Further, in the deformation suppression step, the deformation of the easily compressible deformable member 30 is suppressed by filling the gap between the easily compressible deformable member 30 with a cement-based hardening material. Therefore, the deformation suppressing portion 40 is formed in the gap between the compressible deformable member 30. Therefore, the displacement of the tunnel wall W can be stopped without causing the deformation suppressing part 40 to protrude inward in the radial direction of the tunnel from the compressible deformable member 30, and the cross section of the tunnel T can be prevented from becoming smaller than the designed cross section. I can do it.

Further, after the concrete structure installation process, a tunnel is excavated, and then a deformation suppression process is performed. As the tunnel excavation shaft progresses, the tunnel wall W is displaced and the compressively deformable member 30 is compressively deformed. Therefore, the ground pressure of the ground can be reduced by displacing the tunnel wall W, and the stability of the tunnel T can be improved. Moreover, the deformation of the compressible deformable member 30 can proceed during excavation of the tunnel excavation, and the time required to construct the tunnel T can be shortened.

Although the tunnel support structure 100 and its construction method have been described above, the following modifications are also within the scope of the present invention. It is also possible to combine the configuration shown in the modified example with the configuration described in the above embodiment, or to combine the configurations described in the following different modified examples.

<First modification example>
FIG. 9 is a sectional view of a tunnel support structure 101 according to a first modification of the present embodiment, and FIGS. 9(a) and 9(b) correspond to FIGS. 2(a) and (b), respectively.

In the tunnel support structure 100 shown in FIG. 2, the deformation suppressing portion 40 is filled in the gap between the compressible and deformable members 30. In the tunnel support structure 101, as shown in FIG. 9, the deformation suppressing portion 40 is disposed straddling the compression deformable member 30 in the tunnel circumferential direction. The deformation suppressing portion 40 is made of steel, for example. The deformation suppressing portion 40 is connected to the steel members 10 adjacent to each other in the circumferential direction of the tunnel and the concrete structures 20 adjacent to each other in the circumferential direction of the tunnel, for example, by bolts or welding.

In the method for constructing the tunnel support structure 101, in the deformation prevention step, as shown in FIG. It is connected to a matching steel member 10. Further, as shown in FIG. 9(b), the deformation suppressing part 40 is disposed across the compressible deformable member 30 in the circumferential direction of the tunnel, and is connected to the concrete structure 20 adjacent in the circumferential direction of the tunnel.

The tunnel support structure 101 and its construction method, like the tunnel support structure 100 and its construction method, can prevent the tunnel wall W from displacing more than necessary, and the cross section of the tunnel T becomes smaller than the designed cross section. can be prevented. Thereby, the tunnel T can be constructed efficiently.

In addition, in the tunnel support structure 101 and its construction method, the deformation suppressing portion 40 is disposed straddling the compressively deformable member 30, so that the deformation of the compressively deformable member 30 is prevented regardless of the shape of the compressively deformable member 30. It can be suppressed. Therefore, a solid precast block can be used as the compressible and deformable member 30. As the precast block, for example, a block made of hard urethane resin mixed with glass fiber can be used. Note that while the precast block is compressed and deformed (shrinks) in the circumferential direction of the tunnel, it expands in the radial direction of the tunnel according to Poisson's ratio. When the deformation suppressing part 40 is installed so as to be in contact with the precast block, the deformation suppressing part 40 functions to suppress expansion of the precast block. At this time, the compression rigidity of the precast block in the circumferential direction of the tunnel increases. This effect further enhances the deformation prevention effect of the deformation prevention section 40.

<Second modification example>
FIG. 10 is a sectional view of a tunnel support structure 102 according to a second modification of the present embodiment, and is shown corresponding to FIG. 2(a).

As shown in FIG. 10, the tunnel support structure 102 includes an inner support section 50 that supports the steel member 10, the concrete structure 20, and the compressively deformable member 30 from the inside in the tunnel radial direction. The inner support portion 50 is, for example, shotcrete.

The inner support portion 50 is provided inside the steel member 10, the concrete structure 20, and the compressively deformable member 30 in the tunnel radial direction after the deformation suppression step. Therefore, it is possible to prevent the easily compressible deformation member 30 from being compressed and deformed after the inner support portion 50 is installed, and it is possible to prevent stress in the inner support portion 50 from increasing locally. Therefore, the stability of the tunnel T can be further improved.

<Third modification example>
FIG. 11 is a sectional view of a tunnel support structure 103 according to a third modification of the present embodiment, and is shown corresponding to FIG. 2(b).

In the tunnel support structure 100 shown in FIG. 2, a plurality of concrete structures 20 are provided at intervals in the circumferential direction of the tunnel, and a member 30 that is easily compressed and deformed is provided between the concrete structures 20 adjacent to each other in the circumferential direction of the tunnel. ing. In the tunnel support structure 103, as shown in FIG. 11, the compressively deformable member 30 may be provided between the concrete structure 20 and the bottom surface BT of the tunnel excavation shaft. In other words, the compressible deformable member 30 may be provided adjacent to the concrete structure 20 in the circumferential direction of the tunnel.

Although not shown in the drawings, the compression-deformable member 30 may be provided between the steel member 10 and the bottom surface BT of the tunnel excavation shaft. In other words, the easily compressible deformable member 30 may be provided adjacent to the steel member 10 in the tunnel circumferential direction.

<Fourth variation>
The easily compressible deformable member 30 disposed between the steel members 10 adjacent in the circumferential direction of the tunnel and the easily compressible deformable member 30 disposed between the concrete structures 20 adjacent in the circumferential direction of the tunnel are integrated. You can leave it there. In other words, one compressively deformable member may be provided adjacent to the steel member 10 and the concrete structure 20 in the tunnel circumferential direction.

<Fifth modification example>
Although the tunnel support structure 100 includes both an easily compressible deformable member 30 adjacent to the steel member 10 and an easily compressible deformable member 30 adjacent to the concrete structure 20, the present invention is limited to this form. do not have. Specifically, the present invention may include only the easily compressible deformable member 30 adjacent to the steel member 10. In this case, the compressible deformable member 30 may be provided in the tunnel excavation only in the steel member installation process. Further, the present invention may be configured to include only the easily compressible deformable member 30 adjacent to the concrete structure 20. In this case, the compression-deformable member 30 may be provided inside the tunnel excavation only in the concrete structure installation process.

Although the embodiments of the present invention have been described above, the above embodiments merely show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. do not have.

100, 101, 102, 103... Tunnel support structure 10... Steel member 20... Concrete structure 30... Compressively deformable member 32... Cylindrical part 40... Deformation suppressing part 50 ...Inner support T...Tunnel W...Inner wall of tunnel excavation

Claims (8)

A method for constructing a tunnel support structure, the method comprising:
The tunnel support structure includes a plurality of steel members provided at predetermined intervals in the tunnel axial direction along the wall of the tunnel excavation, a concrete structure provided between the adjacent steel members, and the An easily compressible deformable member that can be compressively deformed more easily than a steel member,
The construction method includes:
The steel member is provided along the tunnel excavation wall at a predetermined interval from the already installed steel member in the tunnel axial direction, and the compressively deformable member is adjacent to the steel member in the tunnel circumferential direction. A steel member installation process,
a concrete structure installation step of providing the concrete structure between the steel members adjacent in the tunnel axial direction;
a deformation inhibiting step of suppressing deformation of the compressively deformable member in the deformation process of the compressively deformably easily deformable member;
The compressively deformable member has a gap that becomes narrower as the compressively deformable member is compressively deformed, and because of the existence of the gap, the stiffness of the compressively deformable member is higher than that of the steel member and the concrete structure. is also low,
In the deformation inhibiting step, deformation of the compressively deformable member is suppressed by filling the gap of the compressively deformable member with a cement-based hardening material.
How to construct a tunnel support structure. A method for constructing a tunnel support structure, the method comprising:
The tunnel support structure includes a plurality of steel members provided at predetermined intervals in the tunnel axial direction along the wall of the tunnel excavation, a concrete structure provided between the adjacent steel members, and the An easily compressible deformable member that can be compressively deformed more easily than a steel member,
The construction method includes:
The steel member is provided along the tunnel excavation wall at a predetermined interval from the already installed steel member in the tunnel axial direction, and the compressively deformable member is adjacent to the steel member in the tunnel circumferential direction. A steel member installation process,
a concrete structure installation step of providing the concrete structure between the steel members adjacent in the tunnel axial direction;
a deformation inhibiting step of suppressing deformation of the compressively deformable member in the deformation process of the compressively deformably easily deformable member;
In the steel member installation step, a plurality of the steel members are provided at predetermined intervals in the circumferential direction of the tunnel, and the easily compressible deformable member is provided between the steel members adjacent in the circumferential direction of the tunnel,
In the deformation suppressing step, a steel material is disposed across the compressively deformable member in the circumferential direction of the tunnel and is connected to the steel member, thereby suppressing deformation of the compressively deformable member.
How to construct a tunnel support structure. A method for constructing a tunnel support structure, the method comprising:
The tunnel support structure includes a plurality of steel members provided at predetermined intervals in the tunnel axial direction along the wall of the tunnel excavation, a concrete structure provided between the adjacent steel members, and the An easily compressible deformable member that can be compressively deformed more easily than a steel member,
The construction method includes:
The steel member is provided along the tunnel excavation wall at a predetermined interval from the already installed steel member in the tunnel axial direction, and the compressively deformable member is adjacent to the steel member in the tunnel circumferential direction. A steel member installation process,
a concrete structure installation step of providing the concrete structure between the steel members adjacent in the tunnel axial direction;
a deformation inhibiting step of suppressing deformation of the compressively deformable member in the deformation process of the compressively deformably easily deformable member;
After the concrete structure installation step, a tunnel is excavated, and then the deformation suppression step is performed.
How to construct a tunnel support structure. A method for constructing a tunnel support structure, the method comprising:
The tunnel support structure includes a plurality of steel members provided at predetermined intervals in the tunnel axial direction along the wall of the tunnel excavation, a concrete structure provided between the adjacent steel members, and the Compressively deformable members that are easier to compressively deform than concrete structures,
The construction method includes:
a steel member installation step of installing the steel member along the tunnel excavation shaft wall at a predetermined interval in the tunnel axial direction from the already installed steel member;
a concrete structure installation step in which the concrete structure is provided between the steel members adjacent in the tunnel axial direction, and the compressively deformable member is provided adjacent to the concrete structure in the tunnel circumferential direction;
a deformation inhibiting step of suppressing deformation of the compressively deformable member in the deformation process of the compressively deformably easily deformable member;
The compressively deformable member has a gap that becomes narrower as the compressively deformable member is compressively deformed, and because of the existence of the gap, the stiffness of the compressively deformable member is higher than that of the steel member and the concrete structure. is also low,
In the deformation inhibiting step, deformation of the compressively deformable member is suppressed by filling the gap of the compressively deformable member with a cement-based hardening material.
How to construct a tunnel support structure. A method for constructing a tunnel support structure, the method comprising:
The tunnel support structure includes a plurality of steel members provided at predetermined intervals in the tunnel axial direction along the wall of the tunnel excavation, a concrete structure provided between the adjacent steel members, and the Compressively deformable members that are easier to compressively deform than concrete structures,
The construction method includes:
a steel member installation step of installing the steel member along the tunnel excavation shaft wall at a predetermined interval in the tunnel axial direction from the already installed steel member;
a concrete structure installation step in which the concrete structure is provided between the steel members adjacent in the tunnel axial direction, and the compressively deformable member is provided adjacent to the concrete structure in the tunnel circumferential direction;
a deformation inhibiting step of suppressing deformation of the compressively deformable member in the deformation process of the compressively deformably easily deformable member;
In the concrete structure installation step, a plurality of the concrete structures are provided at predetermined intervals in the tunnel circumferential direction, and the compressive deformation easy member is provided between the concrete structures adjacent in the tunnel circumferential direction,
In the deformation suppressing step, a steel material is placed across the compressively deformable member in the circumferential direction of the tunnel and is connected to the concrete structure, thereby suppressing deformation of the compressively deformable member.
How to construct a tunnel support structure. A method for constructing a tunnel support structure, the method comprising:
The tunnel support structure includes a plurality of steel members provided at predetermined intervals in the tunnel axial direction along the wall of the tunnel excavation, a concrete structure provided between the adjacent steel members, and the Compressively deformable members that are easier to compressively deform than concrete structures,
The construction method includes:
a steel member installation step of installing the steel member along the tunnel excavation shaft wall at a predetermined interval in the tunnel axial direction from the already installed steel member;
a concrete structure installation step in which the concrete structure is provided between the steel members adjacent in the tunnel axial direction, and the compressively deformable member is provided adjacent to the concrete structure in the tunnel circumferential direction;
a deformation inhibiting step of suppressing deformation of the compressively deformable member in the deformation process of the compressively deformably easily deformable member;
After the concrete structure installation step, a tunnel is excavated, and then the deformation suppression step is performed.
How to construct a tunnel support structure. After the concrete structure installation step, a tunnel is excavated, and then the deformation suppression step is performed.
The method for constructing a tunnel support structure according to any one of claims 1, 2, 4, and 5. After the deformation suppressing step, an inner supporting portion for supporting the tunnel excavation shaft wall is provided inside the steel member, the concrete structure, and the compressively deformable member in the tunnel radial direction.
A method for constructing a tunnel support structure according to any one of claims 1 to 7.

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