Tunnel construction method

Abstract

To provide a tunnel construction method that allows for easy wiring of linear detection parts. [Solution] The tunnel construction method includes the steps of placing a linear first measurement cable 41a along the inner wall of tunnel T, placing a lining formwork 85 so as to cover the inner wall of tunnel T to form a pouring space between the inner wall of tunnel T and the lining formwork 85, providing a communication passage 30a at the bottom of tunnel T that connects the pouring space with an inner space P radially inward of the lining formwork 85 relative to the axis of tunnel T, and pouring concrete into the pouring space with one end of the measurement cable 41 in the pouring space being guided to the inner space P through the communication passage 30a.

Description

[Technical Field]

[0001] The present invention relates to a tunnel construction method. [Background technology]

[0002] Patent Document 1 discloses a stress measurement method for measuring the strain of an optical fiber cable based on light guided by the optical fiber cable of a buried cable buried in sprayed or poured concrete during tunnel construction. In the method described in Patent Document 1, the main body of the stress measuring device is placed on the bottom surface of the excavation hole on the mouth side, and the buried cable buried in the concrete is connected to the main body of the device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-21571 Summary of the Invention [Problem to be solved by the invention]

[0004] In the method disclosed in Patent Document 1, it is necessary to pull out the buried cable in the concrete from the tunnel wall into the inner space of the tunnel and connect it to the device main body. During tunnel construction, construction equipment and the like are present inside the tunnel, so the buried cable needs to be pulled out into the inner space in a way that avoids these equipment, which can make the work complicated.

[0005] An object of the present invention is to provide a tunnel construction method that allows for easy wiring of linear detection units. [Means for solving the problem]

[0006] The present invention is a tunnel construction method, comprising the steps of: arranging linear detectors along the inner wall of a tunnel; of The lining formwork is placed to cover it. tunnel forming a pouring space between the inner wall and the lining formwork; providing a communication passage at the bottom of the tunnel that connects the pouring space with an inner space radially inward of the lining formwork relative to the tunnel axis; and pouring concrete into the pouring space with one end of the detection unit in the pouring space being guided to the inner space through the communication passage. connecting one end of the detection unit led into the internal space to a connection wiring in a duct extending from the tunnel entrance; Including The pipeline section is installed inside the corridor section installed inside the tunnel. . The present invention also provides a tunnel construction method, comprising the steps of: arranging a linear detection unit along the inner wall of the tunnel; arranging a lining formwork to cover the inner wall of the tunnel and forming a pouring space between the inner wall of the tunnel and the lining formwork; providing a communication passage at the bottom of the tunnel that connects the pouring space to an inner space radially inward of the lining formwork relative to the axis of the tunnel; pouring concrete into the pouring space with one end of the detection unit in the pouring space guided to the inner space through the communication passage; excavating the ground to form an invert excavation surface; pouring concrete on the invert excavation surface to form an invert at the bottom of the tunnel; and forming a communication passage in the invert. In the step of forming the invert, concrete is poured with a box-cut formwork for the communication passage provided on the invert excavation surface.

[0007] The present invention also provides a tunnel construction method, comprising the steps of: excavating the ground to form an invert excavation surface; arranging a linear bottom detection unit along the inner wall of the invert excavation surface; and forming an invert at the bottom of the tunnel by pouring concrete onto the invert excavation surface so that the bottom detection unit is embedded. In the step of forming the invert, a communication passage communicating with an inner space located radially inside the tunnel axis is provided. A box cut form for the purpose is installed on the invert excavation surface, and concrete is poured to create a connecting passage. formation death , through the communication passage to the bottom detection section of Leading to the inner space Ku . [Effects of the Invention]

[0008] According to the present invention, a linear detection unit or a bottom detection unit can be easily installed during tunnel construction. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a front view of a tunnel according to an embodiment of the present invention, viewed from the axial direction. [Figure 2] 2 is a cross-sectional view of the tunnel according to the embodiment of the present invention, taken along line II-II in FIG. 1. [Figure 3] FIG. 3 is a perspective view of the lining and the measurement cable, showing a cross section taken along line III-III in FIG. 2. [Figure 4] FIG. 2 is an enlarged cross-sectional view of a portion of a lining body according to an embodiment of the present invention. [Figure 5] FIG. 1 is a flow chart showing a tunnel construction method according to an embodiment of the present invention. [Figure 6] 10A and 10B are cross-sectional views showing the process of placing a second measurement cable in a tunnel construction method according to an embodiment of the present invention, in which (a) shows the state in which a cable support part is installed on the invert excavation surface, (b) shows the state in which the second measurement cable is supported by the cable support part, (c) shows the state in which the invert has been poured, and (d) shows the state in which the invert has been backfilled with soil. [Figure 7] FIG. 2 is a perspective view showing a communication passage of an inverter according to an embodiment of the present invention. [Figure 8] FIG. 1 is a cross-sectional view showing a tunnel construction method according to an embodiment of the present invention, illustrating the state in which a cable support part is placed at the top of the excavation hole. [Figure 9] FIG. 2 is a cross-sectional view showing a tunnel construction method according to an embodiment of the present invention, illustrating a state in which a first measurement cable is supported by a cable support part at the top of the excavation hole. [Figure 10] This is a cross-sectional view showing a tunnel construction method according to an embodiment of the present invention, showing the state in which a lining formwork is placed inside the top of the excavation hole. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0011] The tunnel T construction method of this embodiment is to construct (build) a tunnel T in which a measuring device 40 that measures the displacement of the tunnel T or the stress acting on the tunnel T is provided in the lining concrete.

[0012] First, a measurement device 40 and a tunnel T according to this embodiment will be described with reference to FIGS.

[0013] The tunnel T in this embodiment is a mountain tunnel, and is constructed, for example, by the NATM construction method. The tunnel T is constructed by covering the inner periphery of an excavation hole 1 formed in the natural ground from the inside with a tunnel lining structure 100. The excavation hole 1 of the tunnel T is formed by excavating the natural ground with a shield machine (not shown).

[0014] As shown in Figures 1 and 2, the tunnel lining structure 100 comprises a support structure 10 provided along the inner surface of the excavation hole 1, a lining body 20 provided along the inner surface of the excavation hole 1 so as to cover the support structure 10, an invert 30 that forms the bottom of the tunnel T, a roadbed portion 35 provided on the invert 30, and a measuring device 40 that measures the displacement of the tunnel T or the stress (strain) acting on the tunnel T.

[0015] The excavation hole 1 is a hole of approximately circular cross section, having a top 2 formed in an arch shape (approximately semicircular shape) in a cross section perpendicular to the axis of the tunnel T, and an inverted excavation surface 3 corresponding to the bottom of the tunnel T.

[0016] As shown in Figure 2, the support structure 10 comprises shotcrete 11 sprayed onto the inner wall of the excavation hole 1, and supports 12 installed at predetermined intervals in the axial direction of the tunnel T along the inner circumferential surface of the top 2 of the excavation hole 1. The supports 12 are, for example, H-beams, and are formed in a curved arch shape so as to extend in the circumferential direction of the top 2 of the excavation hole 1.

[0017] Primary shotcrete (not shown) is sprayed onto the inner wall of the excavation hole 1, and shoring 12 is provided along the inner surface of the primary shotcrete. The shotcrete 11 is secondary shotcrete that is sprayed around the entire inner periphery of the excavation hole 1 so as to fill in the spaces between adjacent shoring 12 and between the shoring 12 and the inner wall of the excavation hole 1 (primary shotcrete). In this way, the inner wall of the excavation hole 1 is supported by a support structure 10 consisting of the shoring 12 and the shotcrete 11.

[0018] The lining 20 is formed by lining the inside of the support structure 10 with further concrete. The lining 20 is formed in an arch shape along the inner circumference of the top 2 of the excavation hole 1, and constitutes the inner wall of the tunnel T. The tunnel T is formed by sequentially constructing the lining 20 along the axial direction of the tunnel T. An inner space P is formed inside the lining 20.

[0019] The invert 30 is formed at the bottom of the tunnel T by concrete that is poured in an unhardened state on the inside of the invert excavation surface 3, which is curved in an arc, and then hardened.

[0020] The roadbed portion 35 has a paved surface on which vehicles and the like pass when the tunnel T is in service, and is provided on the invert 30.

[0021] A corridor section 5 extending along the axial direction of the tunnel T is provided on the roadbed section 35 inside the tunnel T. The corridor section 5 is provided to allow workers to pass through the inside of the tunnel T, and is provided near the boundary between the lining body 20 and the invert 30 (see Figure 1).

[0022] The measuring device 40 has a linear first measuring cable 41a (detection unit) for detecting displacement of the lining body 20 of the tunnel T or stress acting on the lining body 20, a linear second measuring cable 41b (bottom detection unit) for detecting displacement of the invert 30 or stress acting on the invert 30, and a measuring unit 60 for acquiring detection results from the first measuring cable 41a and the second measuring cable 41b.

[0023] The first measurement cable 41a is embedded in the lining 20, and the second measurement cable 41b is embedded in the invert 30. The first measurement cable 41a and the second measurement cable 41b have basically the same configuration, except for whether the measurement target is the lining 20 or the invert 30. In the following, when describing the configuration common to the first measurement cable 41a and the second measurement cable 41b, the first measurement cable 41a and the second measurement cable 41b will be collectively referred to as the "measurement cable 41" without distinguishing between them. Furthermore, the configuration of the first measurement cable 41a corresponding to each configuration of the measurement cable 41 will be denoted by adding the suffix "a" to the reference symbol of the measurement cable 41, and the corresponding configuration of the second measurement cable 41b will be denoted by adding the suffix "b" to the reference symbol of the measurement cable 41.

[0024] The measurement cable 41 is, for example, an optical fiber cable. The measurement cable 41 is connected to the measurement unit 60. The optical fiber cable generates strain in response to the displacement (strain) of the tunnel T, and therefore, it is possible to measure the displacement or stress of the tunnel T by measuring the strain of the optical fiber cable.

[0025] 3, the measurement cable 41 is configured by repeating a configuration in which one unit includes a straight section that is provided on one side in the left-right direction (the left side in FIG. 1) when viewed in the axial direction of the tunnel T and extends in the axial direction of the tunnel T, and a crossing section 45 that is connected to the straight section and extends toward the other side in the left-right direction (the right side in FIG. 1). In this embodiment, one unit of measurement cable 41 is provided for one lining body 20.

[0026] The straight portions of the measurement cable 41 include a first straight portion 42 and a second straight portion 43. A crossing portion 45 is provided between the first straight portion 42 and the second straight portion 43.

[0027] The crossing portion 45 of the measurement cable 41 has an inner extending portion 46 that extends circumferentially from one end of the first straight portion 42 to the right side relative to the axis of the tunnel T, a connecting portion 48 that extends from the end of the inner extending portion 46, and an outer extending portion 47 that extends circumferentially from the end of the connecting portion 48 to the left side relative to the axis of the tunnel T and is connected to one end of the second straight portion 43. The inner extending portion 46, the outer extending portion 47, and the connecting portion 48 are arranged on the same cross section perpendicular to the axis of the tunnel T.

[0028] The inner extension 46 and the outer extension 47 are aligned radially relative to the axis of the tunnel T and are provided in an arc shape that curves in accordance with the shape of the excavation hole 1 (top 2 or invert excavation surface 3).

[0029] The connecting portion 48 connects the ends of the inner extending portion 46 and the outer extending portion 47. The end of the inner extending portion 46 opposite to the side connected to the connecting portion 48 is connected to the first straight portion 42. The end of the outer extending portion 47 opposite to the side connected to the connecting portion 48 is connected to the second straight portion 43.

[0030] In the first measurement cable 41a, the first straight portion 42a and the second straight portion 43a are provided in the lining 20 near the boundary with the invert 30, and extend linearly in the axial direction of the tunnel T. In the second measurement cable 41b, the first straight portion 42b and the second straight portion 43b are provided in the invert 30 near the boundary with the lining 20, and extend linearly in the axial direction of the tunnel T. In this way, the straight portions 42, 43 of the measurement cable 41 are gathered together so as to be located on one side of the tunnel T in the left-right direction (the left side in FIG. 1 in this embodiment).

[0031] 4, the inner extension 46a and the outer extension 47a of the first measurement cable 41a are arranged at equal intervals with respect to the central axis O of the lining body 20 in the thickness direction (radial direction relative to the axis of the tunnel T) in a cross section perpendicular to the axis of the tunnel T. In other words, the inner extension 46a and the outer extension 47a are each formed in the shape of a concentric arc with respect to the central axis O of the lining body 20 in the thickness direction, and are arranged side by side on the inside or outside in the radial direction.

[0032] The crossing portion 45a of the first measurement cable 41a and the crossing portion 45b of the second measurement cable 41b may be arranged on the same cross section or on different cross sections.

[0033] The ends of the first measurement cable 41a and the second measurement cable 41b on the tunnel entrance side of tunnel T are drawn out from the lining 20 and the invert 30, respectively, into the interior of tunnel T. The ends of the first measurement cable 41a and the second measurement cable 41b drawn out into the interior of tunnel T are connected to a connection cable 7 (connection wiring), which is an optical fiber cable that passes through a perforated ceramic pipe 6 (pipe section) inside the corridor section 5 and is connected to the measurement unit 60 (see Figures 1 and 2). As a result, the first measurement cable 41a and the second measurement cable 41b are led to the tunnel entrance and connected to the measurement unit 60.

[0034] The measurement unit 60 irradiates the test cable 41 with test light and receives scattered light from the test cable 41. The measurement unit 60 then analyzes the detected scattered light to measure the displacement or strain of the test cable 41 along the extension direction of the test cable 41.

[0035] As described above, the measurement cable 41 has two measurement lines, the inner extension part 46 and the outer extension part 47, that cross the tunnel T on a cross section perpendicular to the axis of the tunnel T. This makes it possible to calculate the bending moment (bending direction) of the tunnel T from the stress state on the inside and outside in the radial direction, and to more accurately measure the state of strain acting on the tunnel T (how the tunnel T is deforming).

[0036] The inner extension 46a and the outer extension 47a of the first measurement cable 41a are provided on the inner and outer sides of the radial direction, respectively, at equal intervals with respect to the central axis O in the thickness direction of the lining body 20 (the radial direction relative to the axis of the tunnel T). This allows the bending moment of the tunnel T to be measured more accurately.

[0037] Furthermore, the straight sections 42 and 43 of the measurement cable 41 are biased to one side in the left-right direction of the tunnel T. This allows the measurement cable 41 to be repaired by working only on one side in the left-right direction, even if the measurement cable 41 is broken. Therefore, even if repairs are to be made to the tunnel T that is currently in use, the repair work can be carried out without closing the entire pavement surface to traffic.

[0038] Next, the tunnel construction method of this embodiment will be described.

[0039] In the following, an example will be described in which a new lining body 20 is constructed in a state in which a lining body 20 has already been constructed.

[0040] The tunnel construction method of this embodiment includes the steps of forming a borehole 1 in the natural ground, placing a measurement cable 41, and forming the inner wall of a tunnel T around the inner periphery of the borehole 1.

[0041] The step of forming the borehole 1 includes the steps of forming the top 2 of the borehole 1 and forming the inverted borehole surface 3 .

[0042] The step of placing the measurement cable 41 includes a step of placing a first measurement cable 41 a on the top 2 and a step of placing a second measurement cable 41 b on the invert excavation surface 3 .

[0043] The process of forming the inner wall of the tunnel T around the inner circumference of the excavation hole 1 includes the steps of constructing a support structure 10 at the top 2, placing a lining formwork 85 at the top 2, pouring concrete at the top 2, and pouring concrete into the invert 30.

[0044] Below, with reference to FIG. 5, each step of the construction method for tunnel T will be explained in chronological order.

[0045] First, in the construction method for the tunnel T, a step of excavating the upper and lower halves of the top 2 of the borehole 1 (step S10) and a step of excavating the invert excavation surface 3 (step S11) are carried out.

[0046] In the process of excavating the upper and lower halves, for example, the top 2 is formed by a bench cut method in which the upper half of the top 2 is excavated first, and then the lower half is excavated. Note that the method of forming the top 2 is not limited to this, and for example, it may be performed by a full cross-section method in which the upper and lower halves of the top 2 are excavated simultaneously.

[0047] Next, in the step of excavating the invert excavation surface 3, the ground (natural ground) below the top 2 is excavated to form the arc-shaped invert excavation surface 3.

[0048] Once the upper and lower halves of the top 2 of the excavation hole 1 and the invert excavation surface 3 have been excavated, primary shotcrete is sprayed onto the inner surfaces of each.

[0049] Next, a step of installing the second measurement cable 41b (step S12) and a step of forming the inverter 30 (step S13) are performed. Steps S12 and S13 will be specifically described below with reference to FIG.

[0050] In the process of installing the second measurement cable 41b, first, as shown in Figure 6(a), a cable support is installed on the inner circumference of the support structure 10 on the invert excavation surface 3. The cable support is, for example, a reinforcing bar. The cable support has first support parts 80 that protrude radially inward from the inner circumference of the support structure 10 and are provided at intervals around the circumference of the tunnel T, and second support parts 81 that extend around the circumference of the tunnel T so as to connect the first support parts 80.

[0051] 6(b), the second measurement cable 41b is supported by the cable support part, whereby the second measurement cable 41b is arranged on the inner periphery of the invert excavation surface 3 along a predetermined path.

[0052] Next, the step of forming the invert 30 is carried out. In this step, as shown in FIG. 6(c), concrete is poured along the inner periphery of the invert excavation surface 3 so as to cover the second measurement cable 41b from the inside. As a result, the invert 30 is formed at the bottom of the tunnel T, and the second measurement cable 41b is buried inside the invert 30.

[0053] When concrete is poured onto the invert excavation surface 3, a cylindrical formwork (not shown) through which the second measurement cable 41b passes is provided on the wellhead side (the existing lining 20 side) at the boundary (so-called shoulder portion) with the lining concrete, and concrete is poured. By pouring concrete into the pouring space with the formwork provided, a communication passage 30a is formed in the invert 30, connecting the interior of the invert 30 with the inner space P of the tunnel T. The communication passage 30a is a so-called box cutout, which is a hole that is a space provided in a part of the invert 30, which is a structure. For example, as shown in FIG. 7, the communication passage 30a is formed as a notch at the end of the invert 30 that forms the boundary with the lining 20. In this way, the process of pouring concrete onto the invert excavation surface 3 also includes the process of forming the communication passage 30a in the invert 30.

[0054] The second measurement cable 41b embedded in the invert 30 extends circumferentially of the tunnel T to the end of the invert 30, which is the boundary with the lining 20, and then extends axially of the tunnel T toward the communicating passage 30a. One end of the second measurement cable 41b is guided through the communicating passage 30a into the inner space P of the tunnel T. In other words, the cross section of the tunnel T where the crossing portion 45b of the second measurement cable 41b is provided does not overlap with the communicating passage 30a but is separated from it in the axial direction of the tunnel T. In this way, the second measurement cable 41b is disposed up to the end of the invert 30 and extracted from the communicating passage 30a into the inner space P, so that displacement can be measured up to the end of the invert 30 where the communicating passage 30a is provided. Furthermore, as will be described later, the lining formwork 85 for forming the lining 20 may be provided to a position that covers a portion of the end of the invert 30 from the radially inner side. Even in such a case, by arranging the second measurement cable 41b up to the end of the invert 30 and extracting it from the connecting passage 30a into the inner space P, it is possible to measure strain up to the end of the invert 30 while preventing interference between the second measurement cable 41b and the lining formwork 85. However, this is not limited thereto, and the cross section of the tunnel T where the crossing portion 45b of the second measurement cable 41b is provided may be configured to overlap with the connecting passage 30a. Furthermore, the end of the measurement cable 41 on the face side is extracted from the end surface of the invert 30 on the face side. In this way, an invert 30 with the second measurement cable 41b installed therein is formed.

[0055] Once the invert 30 is formed, the invert 30 is backfilled with excavated earth and sand (hereinafter simply referred to as "earth and sand S") as shown in Figure 6(d) to allow work vehicles and the like to pass through for forming the lining body 20. This completes step S14.

[0056] Next, a process (step S15 shown in Figure 5) is carried out to construct a support structure 10 around the inner periphery of the top 2 of the excavation hole 1. In this process, a primary sprayed concrete is formed on the top 2 of the excavation hole 1, and supports 12 extending circumferentially along the inner periphery of the primary sprayed concrete are installed at intervals in the axial direction of the tunnel T. Then, secondary sprayed concrete 11 (see Figure 2) is formed around the entire periphery to bury the supports 12. In this way, the support structure 10 for the top 2 is constructed.

[0057] Next, the process of installing the first measurement cable 41a (step S16 shown in Figure 5) is performed. In this process, as shown in Figure 8, a cable support is installed on the inner periphery of the support structure 10 at the top 2 of the excavation hole 1. The cable support has a first support part 82 and a second support part 83, similar to the cable support part of the invert 30. Then, as shown in Figure 9, the first measurement cable 41a is placed along the inner wall of the top 2 so as to be supported by the cable support part. By being supported by the cable support part, the first measurement cable 41a is placed so as to follow the desired path. In addition, one end of the first measurement cable 41a on the portal side is placed so as to be led into the interior of the tunnel T through the communication passage 30a of the invert 30.

[0058] Next, a process of placing the lining formwork 85 (step S17 shown in Figure 5) is performed. In this process, as shown in Figure 10, the lining formwork 85 is installed along the inner circumference of the top 2 so as to cover the support structure 10 and the first measurement cable 41a from the inside. For example, as shown in Figure 7, the lining formwork 85 is placed so as to cover part of the end of the invert 30 from the radially inner side (the lining formwork 85 and part of the invert 30 partially overlap in the radial direction of the tunnel T). In Figure 7, the lower end of the lining formwork 85 is shown by a two-dot chain line. This forms a pouring space between the lining formwork 85 and the inner surface of the top 2. The first measurement cable 41a is contained within the pouring space.

[0059] Next, the process of forming the lining body 20 (step S18 in FIG. 5) is performed. In this process, concrete is poured into the pouring space of the top 2. As a result, the lining body 20 that forms the inner wall of the top 2 is formed, and the first measurement cable 41a is embedded inside the lining body 20. Furthermore, when forming the lining body 20, concrete is poured so as to fill the communication passage 30a through which the first measurement cable 41a and the second measurement cable 41b pass.

[0060] In this way, concrete is poured into the pouring space with the end of the first measurement cable 41a (and the end of the second measurement cable 41b) guided through the communication passage 30a into the inner space P of the tunnel T (see FIG. 10). As a result, the first measurement cable 41a is installed inside the lining body 20.

[0061] Next, a step of connecting the measurement cable 41 to the connection cable 7 (step S19 shown in FIG. 5) is performed. After the lining body 20 is formed, the soil backfilled on the invert 30 is removed, and a roadbed section 35 is formed (paved) on the invert 30. Then, a perforated ceramic pipe 6 and a corridor section 5 are installed on the roadbed section 35. A connection cable 7 for communication is wired inside the perforated ceramic pipe 6 installed inside the corridor section 5.

[0062] One end of the first measurement cable 41a and the second measurement cable 41b, which are led into the tunnel T through the communication passage 30a, is connected to the connection cable 7 in the porous earthenware pipe 6 inside the corridor section 5. As a result, the first measurement cable 41a and the second measurement cable 41b are connected to the measurement unit 60 through the connection cable 7.

[0063] Through the above steps, the tunnel lining structure 100 shown in FIG. 1 is constructed.

[0064] By repeating each of the above steps, the lining body 20 is constructed sequentially along the axial direction of the tunnel T, thereby forming the tunnel T. The first measurement cable 41a and the second measurement cable 41b to be embedded in the newly constructed lining body 20 are connected to the existing first measurement cable 41a and the second measurement cable 41b that are led from the end of the existing lining body 20.

[0065] Generally, when wiring the measurement cable 41, it is necessary to avoid equipment such as the lining formwork 85 installed to cast the lining body 20 and a drainage pipe (not shown) installed on the shoulder of the invert 30 along the axial direction of the tunnel T to excavate the tunnel face. In contrast, in this embodiment, the first measurement cable 41a and the second measurement cable 41b pass through a communication passage 30a installed at the bottom of the tunnel T, so that the first measurement cable 41a can be guided inside the tunnel T. This makes it easy to avoid other equipment inside the tunnel T, such as the lining formwork 85 and the drainage pipe, and makes it easier to wire the first measurement cable 41a and the second measurement cable 41b.

[0066] Next, a modification of this embodiment will be described.

[0067] In the above embodiment, the entire cross section of the invert 30 is formed at once. Alternatively, the left and right halves of the invert 30 may be formed separately. Specifically, first, the invert excavation surface 3 is formed and the support structure 10 is constructed on one side (e.g., the right side) of the cross section perpendicular to the axis of the tunnel T, as in the above embodiment. Next, a cable support is installed inside the support structure 10, and the second measurement cable 41b is supported by the cable support. At this time, a portion of the second measurement cable 41b to be placed on the left cross section is temporarily stored near the center in the left-right direction. In this state, the invert 30 is formed on the right cross section, as in the above embodiment. Once the invert 30 is formed on the right cross section in this way, the invert 30 on the right cross section is temporarily backfilled with soil from the excavated ground. This allows a work vehicle to be placed on the backfilled ground on the right cross section and form the invert 30 on the left cross section.

[0068] Next, in the left cross section, the invert excavation surface 3 is formed and the support structure 10 is constructed, as in the right cross section. Next, a cable support is installed inside the support structure 10 in the left cross section, and a portion of the second measurement cable 41b, which was temporarily stored in the center, is supported by the cable support. Concrete is then poured in the left cross section as well, to form the invert 30. At this time, as in the above embodiment, a communication passage 30a is formed in the shoulder of the left cross section of the invert 30.

[0069] Even in such a modified example, the inverter 30 can be formed in the same manner as in the above embodiment.

[0070] In the above embodiment, the measurement device 40 has a first measurement cable 41a embedded inside the lining 20 and a second measurement cable 41b embedded inside the invert 30. However, a configuration in which both the first measurement cable 41a and the second measurement cable 41b are provided is not essential, and the measurement device 40 may have only either the first measurement cable 41a or the second measurement cable 41b. When the measurement device 40 has only the first measurement cable 41a, step S12 in FIG. 5 is omitted in the tunnel construction method. When the measurement device 40 has only the second measurement cable 41b, step S16 in FIG. 5 is omitted in the tunnel construction method.

[0071] Furthermore, in the above embodiment, the communication passage 30a is formed in the invert 30. In contrast to this, if the tunnel T does not have an invert 30, the communication passage 30a may be formed in the ground constituting the bottom of the tunnel T. When the communication passage 30a is formed in the ground, the communication passage 30a can be formed, for example, by excavating the ground.

[0072] In the above embodiment, when forming the invert 30, concrete is poured using a formwork, so that the communication passage 30a is formed in the invert 30 by a so-called box-cutting method. However, the method for forming the communication passage 30a in the invert 30 is not limited to this, and the communication passage 30a may be formed by cutting a part of the invert 30, for example.

[0073] In the above embodiment, the first straight portions 42a, 42b and the second straight portions 43a, 43b of the first measurement cable 41a and the second measurement cable 41b are provided on one side (the left side) of the left and right sides. However, the wiring paths of the first measurement cable 41a and the second measurement cable 41b are not limited to those in the above embodiment and may be configured arbitrarily. When the first measurement cable 41a or the second measurement cable 41b is taken out from the right side in the left-right direction and connected to the measurement unit 60, a communication path 30a may be formed on the right side of the inverter 30 or the ground, and the first measurement cable 41a or the second measurement cable 41b may be taken out through the communication path 30a.

[0074] In the above embodiment, the first measurement cable 41a is embedded in the lining body 20, and the second measurement cable 41b is embedded in the invert 30. Alternatively, the first measurement cable 41a may be embedded in the sprayed concrete 11 of the support structure 10. Alternatively, a support structure 10 similar to the lining body 20 may be provided inside the invert excavation surface 3, and the second measurement cable 41b may be embedded in the sprayed concrete of the support structure 10.

[0075] In the above embodiment, one crossing portion 45 of the measurement cable 41 is provided for each lining 20 or invert 30. However, multiple crossing portions 45 may be provided within a single lining 20 or invert 30. In this case, a straight portion may be provided to connect the crossing portions 45. When multiple crossing portions 45 are provided, it is desirable to provide multiple setup rebars to determine the positions of the first support portions 80, 82 of the cable support portion. In this case, the first support portions 80, 82 are provided in multiple rows in the circumferential direction corresponding to the number of crossing portions 45. The setup rebars extend along the axial direction of the tunnel T at intervals in the circumferential direction. By installing the first support portions 80, 82 along the setup rebars, it becomes easier to align the positions of the first support portions 80 between different cross sections, thereby improving the efficiency of the installation work of the measurement cable 41.

[0076] According to the above embodiment, the following advantageous effects are achieved.

[0077] The tunnel construction method of this embodiment includes the steps of placing a linear first measurement cable 41a along the inner wall of the tunnel T, placing a lining formwork 85 so as to cover the inner wall of the tunnel T to form a pouring space between the inner wall of the tunnel T and the lining formwork 85, providing a communication passage 30a at the bottom of the tunnel T that connects the pouring space with an inner space P radially inward of the lining formwork 85 relative to the axis of the tunnel T, and pouring concrete into the pouring space with one end of the measurement cable 41 in the pouring space being guided to the inner space P through the communication passage 30a.

[0078] In addition, the tunnel construction method of this embodiment includes the steps of excavating the ground to form an invert excavation surface 3, placing a linear second measurement cable 41b along the inner wall of the invert excavation surface 3, and pouring concrete onto the invert excavation surface 3 so that the second measurement cable 41b is embedded to form an invert 30 at the bottom of the tunnel T. In the step of forming the invert 30, a communication passage 30a is formed in the tunnel T that communicates with an inner space P located radially inside the axis of the tunnel T, and the second measurement cable 41b is guided to the inner space P through the communication passage 30a.

[0079] In addition, the tunnel construction method of this embodiment includes a step of excavating the ground to form an invert excavation surface 3, a step of pouring concrete onto the invert excavation surface 3 to form an invert 30 at the bottom of the tunnel T, and a step of forming a connecting passage 30a in the invert 30.

[0080] In these configurations, the first measurement cable 41a or the second measurement cable 41b passes through the communication passage 30a provided at the bottom of the tunnel T, so that the first measurement cable 41a or the second measurement cable 41b can be easily guided into the tunnel T while avoiding other facilities inside the tunnel T, such as the lining formwork 85 and drainage pipes. This makes it easier to wire the first measurement cable 41a or the second measurement cable 41b.

[0081] In addition, the tunnel construction method of this embodiment further includes a step of placing a linear second measurement cable 41b along the invert excavation surface 3, and in the step of forming the invert 30, concrete is poured onto the invert excavation surface 3 so that the second measurement cable 41b is embedded.

[0082] In this configuration, the second measurement cable 41b also passes through the communication passage 30a, so that the second measurement cable 41b can be easily guided to the inside of the tunnel T while avoiding other equipment in the tunnel T. This makes it easier to wire the second measurement cable 41b.

[0083] In addition, the tunnel construction method of this embodiment further includes a step of connecting one end of the first measurement cable 41a led into the inner space P to another connection cable 7 inside a porous ceramic pipe 6 extending from the entrance of the tunnel T, and the porous ceramic pipe 6 is installed inside a corridor section 5 installed inside the tunnel T.

[0084] In this configuration, the first measurement cable 41a is connected to the measurement unit 60 without protruding into the inner space P of the inner wall of the tunnel T. This makes it possible to avoid interference of the first measurement cable 41a with mechanical equipment used for tunnel construction and equipment installed inside the tunnel T while the tunnel T is in service, thereby reducing the risk of the first measurement cable 41a being broken.

[0085] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments. [Explanation of symbols]

[0086] 3: Invert excavation surface 5: Corridor 6: Porous ceramic pipe (pipe section) 7: Connection cable (connection wiring) 30: Invert 30a: Communication path 41a: First measuring cable (detection part) 41b: Second measurement cable (bottom detection part) 85: Lining formwork T: Tunnel

Claims

1. A tunnel construction method comprising: disposing a linear detector along an inner wall of the tunnel; A process of placing a lining formwork so as to cover the inner wall of the tunnel and forming a casting space between the inner wall of the tunnel and the lining formwork; A step of providing a communication passage at the bottom of the tunnel that communicates the pouring space with an inner space radially inside the lining formwork relative to the axis of the tunnel; Pouring concrete into the pouring space with one end of the detection unit in the pouring space being guided to the inner space through the communication passage; and connecting one end of the detection unit led into the internal space to a connection wiring in a duct extending from the tunnel entrance, The pipeline section is provided inside a corridor section provided in the tunnel. Tunnel construction methods.

2. A tunnel construction method comprising: disposing a linear detector along an inner wall of the tunnel; A process of placing a lining formwork so as to cover the inner wall of the tunnel and forming a casting space between the inner wall of the tunnel and the lining formwork; A step of providing a communication passage at the bottom of the tunnel that communicates the pouring space with an inner space radially inside the lining formwork relative to the axis of the tunnel; Pouring concrete into the pouring space with one end of the detection unit in the pouring space being guided to the inner space through the communication passage; excavating the ground to form an invert excavation surface; pouring concrete onto the invert excavation surface to form an invert at the bottom of the tunnel; forming the communication passage in the invert; In the step of forming the invert, concrete is poured in a state where a box-cut formwork for the communication passage is provided on the invert excavation surface. Tunnel construction methods.

3. The tunnel construction method according to claim 2, The method further includes a step of arranging a linear bottom detection unit along the invert excavation surface, In the step of forming the invert, concrete is poured onto the invert excavation surface so that the bottom detection unit is embedded. Tunnel construction methods.

4. A tunnel construction method comprising: excavating the ground to form an invert excavation surface; A step of arranging a linear bottom detection unit along the inner wall of the invert excavation surface; and forming an invert at the bottom of the tunnel by pouring concrete onto the invert excavation surface so that the bottom detection unit is embedded, In the step of forming the invert, a box-cut form for a communication passage that communicates with an inner space located radially inside the axis of the tunnel in the tunnel is provided on the invert excavation surface, concrete is poured to form the communication passage, and the bottom detection unit is led to the inner space through the communication passage. Tunnel construction methods.

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