Vibration receiving device and installation method thereof

Abstract

To provide a vibration receiving device and its installation method capable of improving the measurement accuracy of elastic waves from the front of a working face by blasting and facilitating installation.SOLUTION: The vibration-receiving device (10) includes a geophone (11) for detecting an elastic wave (6) generated by drilling and blasting, a signal transmission member (cable (12)) for transmitting data detected by the geophone (11), a recording unit (data logger (13)) for recording the data, a protection member (14) for protecting the cable (12), and a soundproof member (15) interposed between an outer peripheral surface of the data logger (13) and an inner peripheral surface of the vibration-receiving hole (5).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a seismic receiver used in a tunnel face ahead detection system and a method for installing the same. [Background technology]

[0002] In mountain tunnel construction, it is important to understand in advance the rock mass information, such as fracture zones and spring water zones, which may cause problems during construction. In order to understand the rock mass information in advance, underground reflection seismic surveys using the principles of reflection seismic surveys have been carried out. TSP (Tunnel Seismic Prediction) is known as a conventional method of underground reflection seismic surveys. TSP is a method developed by Amberg of Switzerland. TSP is a technology that predicts the ground conditions ahead of the tunnel face by generating vibrations (elastic waves) through sequential blasting in multiple blast holes drilled into the tunnel wall, and receiving and analyzing the reflected waves from crushed zones and other areas with receivers in multiple receiver holes. Details of TSP are disclosed, for example, in Non-Patent Document 1.

[0003] However, TSP had the problem of requiring construction to be interrupted because exploration was carried out using blasting specifically for exploration, which reduced construction efficiency. To solve this problem, a long-distance exploration method using tunnel excavation blasting as the seismic source (T-BEP (Taisei-Blast Excavation Prospecting) (registered trademark)) was developed. Details of T-BEP are disclosed in Patent Document 1, for example. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Katsuhisa Yotsuzuka and Shigeru Shinohara, Tunnel Face Prediction System TSP303: Predicting the Presence of Fault Zones, Geological Boundaries, and Springs Ahead of the Tunnel Face Using 3D Analysis of Seismic Reflection Method, Construction Machinery Construction, Vol. 68, No. 5, May 2016 [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-24089 Summary of the Invention [Problem to be solved by the invention]

[0006] In the TSP mentioned above, because the seismic source is the exploration blast, drilling work must be interrupted when the exploration ahead of the face is carried out, which results in the problem of prolonging the drilling work.In addition, with the long-distance exploration method (T-BEP), there is a gap between the seismic logger installed at the hole mouth and the hole wall, which allows the blasting sound to enter the hole, and the cable connecting the seismic logger and the seismometer comes into contact with the hole wall, which causes noise in the measurement results.

[0007] From this perspective, an object of the present invention is to provide a receiving device and an installation method thereof that can improve the accuracy of measuring elastic waves from in front of the face caused by blasting. [Means for solving the problem]

[0008] The first invention for solving the above problem is a receiving device installed in a receiving hole drilled in the wall surface of a tunnel shaft, characterized in that it comprises a receiver that detects elastic waves generated by excavation and blasting, a signal transmission member that transmits data detected by the receiver, a recording unit that records the data, a protective member that protects the signal transmission member, and a soundproofing member interposed between the outer surface of the recording unit and the inner surface of the receiving hole. In the vibration receiving device of the present invention, it is preferable that the signal transmission member is a cable and the recording unit is a data logger. With this configuration, a protective member is attached to the signal transmission member (cable), so the signal transmission member (cable) does not interfere with the inner surface of the vibration receiving hole. In addition, a soundproofing member is interposed in the gap between the recording unit (data logger) and the vibration receiving hole, making it difficult for blasting sounds to enter the vibration receiving hole. This makes it difficult for noise to be introduced into the measurement results, thereby improving measurement accuracy.

[0009] In the vibration receiving device of the present invention, the protective member preferably has a tubular core material attached to the outer circumferential surface of the cable and an outer circumferential surface of the core material, and the outer circumferential surface of the core material is preferably made of a softer material than the core material. With this configuration, the protective member has a relatively hard core material, making it easy to attach to the cable. Furthermore, the soft outer circumferential surface of the vibration receiving hole makes it less likely to get caught.

[0010] In the vibration receiving device of the present invention, the outer surface of the exterior material preferably has an uneven shape. With this configuration, the contact area between the exterior material and the inner surface of the vibration receiving hole is small, so the exterior material is less likely to get caught on the inner surface of the vibration receiving hole when the protective member is attached. Furthermore, since the convex parts of the exterior material abut the inner surface, the protective member is stably held in the vibration receiving hole 5.

[0011] In the vibration receiving device of the present invention, it is preferable that at least one of the core material and the exterior material has vibration absorbing properties. With this configuration, vibrations are less likely to be transmitted to the cable, which reduces noise generation and further improves measurement accuracy.

[0012] In the vibration receiving device of the present invention, the cable preferably has a slack forming section that forms slack for installing the vibration receiving device in the vibration receiving hole, and the slack forming section is preferably formed in a spiral shape with an outer diameter smaller than the inner diameter of the vibration receiving hole. With this configuration, the cable extends when installing the vibration receiving device, so that the vibration receiving device, protective member, and data logger can be inserted sequentially into the vibration receiving hole. This makes it easier to install the vibration receiving device in the vibration receiving hole.

[0013] In the vibration receiving device of the present invention, the straight sections of the cable located on both sides of the excess length forming section are preferably connected by an elastic body that can expand and contract, and the cable in the excess length forming section shrinks to its shortest length after installation of the device. With this configuration, the cable does not sag after installation in the vibration receiving hole of the vibration receiving device, so the cable does not come into contact with the inner surface of the vibration receiving hole. This makes it less likely that noise will be introduced into the measurement results, further improving measurement accuracy.

[0014] In the geophone device of the present invention, it is preferable that the geophone comprises a main body and a holder that extends and retracts from the main body and presses against the inner circumferential surface of the geophone hole, and the data logger comprises an input means for extending and retracting the holder. With this configuration, the geophone can be installed in the geophone hole in a stable state.

[0015] The second invention for solving the above problem is a method for installing a geodesic device, comprising a first installation step of inserting a geodesic device that detects elastic waves generated by excavation and blasting and a data transmission cable connected to the geodesic device into a geodesic hole drilled in the wall surface of a tunnel, an installation step of attaching a protective member to the cable inside the geodesic hole, and a second installation step of installing a data logger that records measurement data detected by the geodesic device at the opening of the geodesic hole, characterized in that a soundproofing member is attached to the outer peripheral surface of the data logger before the second installation step. According to the method for installing a vibration receiving device of the present invention, the vibration receiving device can be smoothly and easily installed in the vibration receiving hole. Furthermore, the cable does not interfere with the inner peripheral surface of the vibration receiving hole, and the blasting sound is less likely to penetrate into the vibration receiving hole. This reduces the amount of noise in the measurement results, thereby improving measurement accuracy.

[0016] In the method for installing a geophone according to the present invention, in the first installation step, the input means provided on the data logger is pressed to project a holding part installed on the geophone so as to be able to protrude and press it against the inner wall of the geophone hole, thereby positioning the geophone. According to this method, the work of extending and retracting the holding part can be easily performed.

[0017] In the method for installing a geophone device of the present invention, in the first installation step, a push-in member is fitted to the geophone, the geophone is pushed into the geophone hole, the holding part is protruded to position the geophone, and then the push-in member is pulled out. With this method, the geophone can be easily pushed deep into the geophone hole and positioned. [Effects of the Invention]

[0018] According to the vibration receiving device and the installation method of the present invention, it is possible to improve the accuracy of measuring elastic waves from in front of the face caused by blasting. [Brief explanation of the drawings]

[0019] [Figure 1] This is an overall configuration diagram of the face ahead detection system. [Figure 2] FIG. 1 is a cross-sectional view showing a vibration receiving device according to an embodiment. [Figure 3] FIG. 1 is a cross-sectional view showing a geophone. [Figure 4] FIG. 2 is a front view showing the input means on the surface of the data logger. [Figure 5] (a) is a side cross-sectional view of the inside of the pushing member, and (b) is a side cross-sectional view of the inside of the base part of the receiver. [Figure 6] FIG. 10 is a cross-sectional view showing a conventional vibration receiving device. [Figure 7] 1A is a spectrum diagram of an elastic wave detected by a conventional vibration receiving device, and FIG. 1B is a spectrum diagram of an elastic wave detected by the vibration receiving device according to the embodiment. [Figure 8] FIG. 10 is a cross-sectional view showing a vibration receiving device according to a second embodiment. [Figure 9] 10A and 10B are diagrams showing the cable slack forming portion of the vibration receiving device of the second embodiment, where (a) is an enlarged side view showing the contracted state, and (b) is an enlarged side view showing the extended state. [Figure 10] FIG. 10 is a cross-sectional view showing the installation state of a vibration receiving device according to a second embodiment in a vibration receiving hole. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Each drawing is merely a schematic illustration to allow a sufficient understanding of the present invention. Therefore, the present invention is not limited to the illustrated examples. In each drawing, common or similar components are designated by the same reference numerals, and redundant explanations thereof will be omitted.

[0021] Fig. 1 is a diagram showing the overall configuration of a tunnel tunnel inspection system that employs a seismic receiving device according to an embodiment. As shown in Fig. 1, the tunnel inspection system includes a blasting device 1, a detector 2, and a seismic receiving device 10 according to an embodiment of the present invention. The blasting device 1 is a device that initiates excavation blasting. In excavation blasting, explosives (not shown) placed at the tunnel face 3 are detonated to break up the natural ground. The blasting device 1 is connected to the explosives by a blasting main line 4. The blasting device 1 is placed closer to the tunnel entrance than the vibration receiving hole 5 drilled into the tunnel wall surface. As tunnel excavation progresses, the blasting device 1 may be placed closer to the face than the vibration receiving hole 5.

[0022] The detector 2 detects shot marks that indicate the start timing of excavation blasting. The detector 2 is connected to a data logger 13, which is a recording unit of the seismic receiver 10, so that they can communicate wirelessly (e.g., WiFi (registered trademark)). The detector 2 transmits the detected shot marks to the data logger 13. The detector 2 is connected to the blasting machine 1 via a coaxial cable 9, and is placed inside the tunnel on the tunnel entrance side of the blasting machine 1. Note that the recording unit is not limited to the data logger 13. The recording unit may be another device, such as a recording device equipped with a memory card.

[0023] Fig. 2 is a cross-sectional view showing a vibration receiving device according to an embodiment. The vibration receiving device 10 detects and records elastic waves generated by excavation blasting and is installed in a vibration receiving hole drilled in the wall surface of the tunnel. The vibration receiving device 10 includes a vibration receiver 11, a cable 12, a data logger 13, a protective member 14, and a soundproofing member 15.

[0024] The receiver 11 detects elastic waves 6 generated by the excavation blast. The receiver 11 is a roughly rod-shaped body with a diameter smaller than the diameter of the receiver hole 5, and is placed at the back (tip) of the receiver hole 5. The elastic waves 6 are reflected by the crushed zone 7 in front of the tunnel face, and then reach the receiver 11 through the natural ground.

[0025] 3 is a cross-sectional view of the geophone 11, showing the holder 24 protruding outward. As shown in FIG. 3, the geophone 11 includes a housing 21 serving as the main body, a cap 22, a geophone 23, the holder 24, and a motor 25.

[0026] The housing 21 is a generally cylindrical body. A holding unit 24 in a closed state (retracted state) and a motor 25 are disposed in a hollow portion of the housing 21. A part of the side surface of the housing 21 is open, and the holding unit 24 housed in the housing 21 can protrude radially outward through the opening in the side surface. The cap 22 is the head of the geophone 11 and is connected to the tip of the housing 21. The geophone 23 is a sensor (seismometer) that detects elastic waves 6 reflected from the fracture zone 7 by the excavation blast. The geophone 23 is received in the cap 22.

[0027] The holding part 24 is a member that fixes the geophone 11 to the hole wall of the vibration receiving hole 5. The holding part 24 comprises a block 241, a pair of first arms 242, 242, a second arm 243, and an actuator 244. A parallel link mechanism is formed by the block 241, the pair of first arms 242, 242, and the actuator 244. The block 241 is the part that abuts against the hole wall of the vibration receiving hole 5 when the holding part 24 is in an open state (protruding state). A pair of first arms 242, 242 connect the block 241 and the actuator 244. A second arm 243 connects the block 241 and the side surface of the base of the housing 21. The actuator 244 is driven by the motor 25 to move in the axial direction.

[0028] When motor 25 rotates forward, it moves actuator 244 in the forward axial direction (from the base of housing 21 toward cap 22), and when motor 25 rotates backward, it moves actuator 244 in the reverse axial direction (from cap 22 toward the base of housing 21). When actuator 244 is moved in the forward axial direction, the parallel link mechanism unfolds and holding portion 24 is in a protruding state (see FIG. 3), and when actuator 244 is moved in the reverse axial direction, the parallel link mechanism is folded and holding portion 24 is in a retracted state. In addition, in Figure 3, an end cap 27 that covers the base of the housing 21 is shown, but when the geophone 11 is in use, the end cap 27 is removed and the cable 12 is connected to the geophone 11.

[0029] As shown in Figure 2, cable 12 is a signal transmission member that transmits data detected by geophone 11. Cable 12 connects geophone 11 and data logger 13 so that they can communicate with each other, and is installed in the middle of geophone hole 5. When the survey ahead of the working face is completed, the worker removes data logger 13 from the entrance of geophone hole 5, and then reels in cable 12 to easily retrieve geophone 11 located at the back of geophone hole 5. Note that the signal transmission member is not limited to cable 12. The signal transmission member may be any other linear member, such as an optical fiber cable.

[0030] The data logger 13 is a device that records various data. The data logger 13 receives and records data on the elastic waves 6 transmitted from the geophone 11 via the cable 12. The data logger 13 includes a wireless unit (not shown), a recording unit (not shown), and an input means (not shown). The wireless unit is a functional unit that receives shot marks from the detector 2 via wireless communication. The recording unit is a functional unit that records data on the elastic waves 6 detected by the geophone 23 of the geophone 11. The input means is a means for operating the holding unit 24 of the geophone 11 to retract. The input means is, for example, a switch provided at a position exposed to the outside of the receiving hole 5 (see Figure 4). Note that the input means is not limited to a switch, and may be a mechanism that receives a retraction signal via wireless communication and operates the holding unit 24. The data logger 13 is placed at the entrance of the vibration receiving hole 5. The data logger 13 has a cylindrical main body 51 with a diameter smaller than the diameter of the vibration receiving hole 5, and a disk-shaped flange 52 with a diameter larger than the diameters of the main body 51 and the vibration receiving hole 5. The data logger 13 is positioned by inserting the main body 51 into the vibration receiving hole 5 and engaging the flange 52 with the open end of the vibration receiving hole 5.

[0031] Figure 4 is a front view showing the input means on the surface of the data logger. As shown in Figure 4, a protrusion switch 53 and a retraction switch 54 are provided on the inner surface of the tunnel hole of the flange portion 52, which serve as input means for extending and retracting the holding portion 24. The input means controls the operation of the motor 25, which extends and retracts the holding portion 24, and transmits an activation signal for the motor 25. When the operator presses the protrusion switch 53, the holding portion 24 extends and retracts, pressing against the wall of the receiving hole 5. When the operator presses the retraction switch 54, the holding portion 24 retracts into the housing 21, releasing the geophone 11 from its fixed position. A power switch 55 for the data logger 13 and a card holder 56 for storing an SD card for data storage are also provided on the inner surface of the tunnel hole of the flange portion 52.

[0032] The protective member 14 is a member that protects the cable 12 and is provided to surround the cable 12. The protective member 14 is made of a resin such as urethane. The protective member 14 has a core material 31 and an exterior material 32. The core material 31 is a tubular member that is attached to the outer surface of the cable 12 and is made of a relatively hard resin. The core material 31 has vibration absorption properties and sound absorption properties. The inner diameter of the core material 31 is larger than the outer diameter of the cable 12, making it easy to attach the core material 31 to the outer surface of the cable 12. The exterior material 32 is a component attached to the outer circumferential surface of the core material 31 and is made of a resin material (e.g., urethane sponge) that is softer than the core material 31. The exterior material 32 has vibration-absorbing and sound-absorbing properties. The exterior material 32 is bonded to the outer circumferential surface of the core material 31, and the core material 31 and the exterior material 32 are integrated together. The outer circumferential surface of the exterior material 32 has an uneven shape and is formed with a corrugated cross section. The exterior material 32 has multiple protrusions 33 formed around its entire periphery that abut against the inner circumferential surface of the vibration receiving hole 5 from the inside, thereby fixing the protective member 14 inside the vibration receiving hole 5. Furthermore, by reducing the contact area of ​​the exterior material 32 with the inner circumferential surface of the vibration receiving hole 5, the coefficient of friction with the hole wall can be reduced, making it easier to insert the exterior material 32 into the vibration receiving hole 5.

[0033] The soundproofing member 15 is a member interposed between the outer peripheral surface of the data logger 13 and the inner peripheral surface of the vibration receiving hole 5. The soundproofing member 15 is a tubular member made of, for example, butyl rubber, and also has vibration-damping properties. The soundproofing member 15 is wrapped around the main body 51 of the data logger 13. The thickness dimension of the soundproofing member 15 is the same size as the gap between the outer peripheral surface of the main body 51 and the inner peripheral surface of the vibration receiving hole 5. Multiple soundproofing members 15 (three in this embodiment, on the hole opening side, in the middle, and at the back) are provided at predetermined intervals in the axial direction of the main body 51.

[0034] Next, we will explain the installation method of the above-configured vibration receiving device 10. The installation method of the vibration receiving device 10 according to this embodiment includes a first installation step, a mounting step, and a second installation step. The first installation step involves inserting the geophone 11 and the cable 12 connected to it into the receiving hole 5 drilled in the tunnel wall. In this step, the cable is connected to the geophone 11 in advance, and the geophone 11 is pushed into a predetermined position deep inside the receiving hole 5 with the holding part 24 of the geophone 11 retracted. The geophone 11 is pushed into the receiving hole 5 via a pushing member 100 (see Figure 5) attached to the base end (the end near the hole opening) of the geophone 11. The pushing member 100 is cylindrical, and the geophone 11 is pushed in with the cable 12 inserted through its hollow interior. Once the geophone 11 is pushed into the predetermined position, the protrusion switch 53 of the input means of the data logger 13 is pressed to expand the holding part 24 and press it against the wall of the receiving hole 5, thereby positioning the geophone 11. Once positioning is complete, the pushing member 100 is withdrawn.

[0035] The structure of the pusher member 100 will be described below. Figure 5 (a) is a side-view internal cross-sectional view of the pushing member, and (b) is a side-view internal cross-sectional view of the base of the geophone. As shown in Figure 5 (a), the pushing member 100 is a cylindrical body that pushes the geophone 11 deep into the receiving hole 5. The pushing member 100 has multiple rod portions 101, multiple joint portions 102, and guide receiving portions 103, 103. The geophone 11 has guide portions 36, 36 formed at its base. The pushing member 100 is connected to the guide portions 36. The rod portion 101 is a square cylindrical body that constitutes the main body of the pushing member 100 . The joints 102 connect adjacent rod portions 101. By adding rod portions 101 using the joints 102, the overall length of the pushing member 100 can be adjusted. The guide receiving portions 103, 103 receive the guide portions 36, 36 of the geophone 11. The guide receiving portions 103, 103 are connected to the tip of the leading rod portion 101, and extend from the tip of the leading rod portion 101 in the axial direction of the pushing member 100 and opposite the geophone 11.

[0036] As shown in Figure 5 (b), the guide portions 36, 36 of the geophone 11 are needle-shaped bodies that extend from the base of the geophone 11 in the axial direction of the geophone 11 and so as to face the pushing member 100. The guide portions 36, 36 are received in the guide receiving portions 103, 103, thereby aligning the rotational position of the pushing member 100 around its axis with the rotational position of the geophone 11 around its axis. Because the rod portion 101 has a square cylindrical shape, it can be seen that the guide receiving portion 103 is horizontal when inserted into the core material 31. Suppose that the geophone 11 is placed in a predetermined position (out of reach of a worker) within the geophone hole 5 with the cable 12 connected to the base of the geophone 11. When the worker wants to push the geophone 11 deep into the geophone hole 5, the worker receives the guide parts 36, 36 into the guide receiving parts 103, 103. The worker then pushes the pushing member 100 deep into the geophone hole 5, thereby pushing the geophone 11 deep into the geophone hole 5 and placing the geophone 11 in the desired position.

[0037] The attachment process is a process of attaching the protective member 14 to the cable 12 inserted into the vibration receiving hole 5. In this process, the protective member 14 is inserted into the vibration receiving hole 5 so that the cable 12 passes through the hollow portion of the protective member 14, in which the core material 31 and the outer material 32 are integrated. At this time, since the core material 31 is relatively hard, it is easy to push it along the cable 12. In addition, since the outer surface of the outer material 32 has an uneven shape, the contact area with the inner surface of the vibration receiving hole 5 is small, and frictional resistance is reduced. Furthermore, since the outer material 32 is relatively soft, it can come into contact with the inner surface of the vibration receiving hole 5 and deform toward the opening of the hole. Therefore, the outer material 32 is unlikely to get caught on the inner surface of the vibration receiving hole 5 and can be smoothly pushed deep into the hole, making it easy to install the protective member 14.

[0038] The second installation step is a step of installing the data logger 13 at the opening of the vibration receiving hole 5. Before the second installation step, a soundproofing member 15 is attached to the outer peripheral surface of the main body 51 of the data logger 13 in advance. In the second installation step, the data logger 13 together with the soundproofing member 15 is pushed into the opening of the vibration receiving hole 5. At this time, the outer peripheral surface of the soundproofing member 15 slides against the inner peripheral surface of the vibration receiving hole 5 and is fitted into the vibration receiving hole 5. As a result, the gap between the data logger 13 and the vibration receiving hole 5 is filled with the soundproofing member 15, making it difficult for blasting sounds to enter the vibration receiving hole 5.

[0039] Next, to compare the vibration receiving device 10 of this embodiment with a conventional vibration receiving device, we will explain a comparison experiment in which each vibration receiving device was installed in approximately the same location and elastic waves from the same blast were simultaneously measured. Figure 6 is a cross-sectional view of the conventional vibration receiving device, Figure 7(a) is a spectrum diagram of elastic waves detected by the conventional vibration receiving device, and Figure 7(b) is a spectrum diagram of elastic waves detected by the vibration receiving device of this embodiment. As shown in Figure 6, the conventional vibration receiving device does not have a protective member attached to the cable 12, and no soundproofing member attached to the data logger 13. As a result, the cable 12 comes into contact with the inner surface of the vibration receiving hole 5, creating a gap between the data logger 13 and the vibration receiving hole 5.

[0040] When elastic waves were measured using the receiver shown in Figure 6, it was found that the amplitude exceeded 0.15 and noise was present at frequencies of 175 Hz, 210 Hz, and 375 Hz, as shown in Figure 7(a). The cause of this noise is thought to be that the cable 12 and data logger 13 came into contact with the inner surface of the receiver hole 5, causing vibrations to be transmitted to the cable 12 and data logger 13, and that the blasting sound entered through the gap between the data logger 13 and the receiver hole 5, affecting the receiver 11. When the same elastic waves were measured using the vibration receiving device 10 of this embodiment, in which the above-mentioned causes had been eliminated by attaching the protective member 14 and the soundproofing member 15, it was confirmed that the signal was dominant in the 40 Hz frequency range, as shown in Figure 7(b), and it was found that the noise countermeasures had been effective.

[0041] In other words, with the geophone device 10 according to the embodiment of the present invention, the cable 12 is fitted with a protective member 14, so that the cable 12 does not interfere with the inner surface of the geophone hole 5. Furthermore, the protective member 14 absorbs sound waves propagating through the air and suppresses vibrations of the cable 12 that accompany the initial movement. This reduces noise pick-up when the geophone 11 detects vibrations (elastic waves). Furthermore, a soundproofing member 15 is installed in the gap between the data logger 13 and the geophone hole 5, making it difficult for blasting sounds to penetrate the geophone hole 5. Furthermore, the soundproofing member 15 absorbs sound waves propagating through the air and suppresses vibrations of the data logger 13 that accompany the initial movement. This prevents the geophone 11, cable 12, and data logger 13 from being affected by blasting sounds and vibrations, reducing noise pick-up in the measurement results and improving measurement accuracy. Furthermore, the earthquake receiving device 10 of this embodiment can be easily installed and removed.

[0042] The protective member 14 has a relatively hard core material 31, making it easy to attach to the cable 12 inside the vibration receiving hole 5. The outer jacket material 32 is relatively soft, making it less likely to get caught on the inner circumferential surface of the vibration receiving hole 5 and easier to insert into the vibration receiving hole 5. Furthermore, the outer circumferential surface of the outer jacket material 32 has an uneven shape, which reduces the contact area between the outer jacket material 32 and the inner circumferential surface of the vibration receiving hole 5, making it less likely for the outer jacket material 32 to get caught on the inner circumferential surface of the vibration receiving hole 5. Furthermore, the convex portions 33 of the outer jacket material 32 abut against the inner circumferential surface of the vibration receiving hole 5, so the protective member 14 is held stably inside the vibration receiving hole 5. Furthermore, the core material 31 and outer jacket material 32 of the protective member 14 have vibration absorption properties, making it difficult for vibrations to be transmitted from the vibration receiving hole 5 to the cable 12, reducing noise generation and further improving measurement accuracy. The geophone 11 is provided with a holding portion 24, and the data logger 13 is provided with an input means for extending and retracting the holding portion 24, so that the geophone 11 can be easily inserted into the receiving hole 5 with the holding portion 24 retracted, and the geophone 11 can be stably mounted in the receiving hole 5 with the holding portion 24 protruding.

[0043] FIG. 8 is a cross-sectional view showing a vibration receiving device according to a second embodiment, and FIG. 9 is a diagram showing the excess length forming portion of the cable of the vibration receiving device according to the second embodiment, where (a) is an enlarged side view showing the contracted state, (b) is an enlarged side view showing the extended state, and FIG. 10 is a cross-sectional view showing the vibration receiving device according to the second embodiment installed in a vibration receiving hole. As shown in FIG. 8, the vibration receiving device 110 of the second embodiment includes a vibration receiver 11, a cable 112, a data logger 13, a protective member 14, and a soundproofing member 15. The vibration receiving device 110 of this embodiment differs in the shape of the cable 112 from the cable 12 of the previous embodiment. Note that the other configurations are the same as those of the previous embodiment, so the same reference numerals are used and their description will be omitted.

[0044] As shown in Figures 8 and 9, the cable 112 has a slack forming section 113 and a straight section 114. The slack forming section 113 is a section for forming slack for installing the vibration receiving device 110 in the vibration receiving hole 5, and is stretchable. The slack forming section 113 has a curled cord shape in which the cable main body is wound in a spiral (coil) shape, and is stretchable. In other words, the slack forming section 113 can be stretched by pulling both sides or one side, and can form slack that is equal to or greater than the distance between the vibration receiving device 11 and the data logger 13. The slack forming section 113 has an outer diameter smaller than the inner diameter (diameter) of the vibration receiving hole 5. In this embodiment, the outer diameter of the slack forming section 113 is smaller than the inner diameter of the protective member 14. The slack forming section 113 is formed to have a length equivalent to the axial length of the protective member 14 in a contracted state, and is configured to be housed inside the protective member 14. The length of the surplus length forming part 113 is not limited to the above shape, and may be shorter or longer than the protective member 14. The position of the surplus length forming part 113 is not limited to the above shape, and may be arranged closer to the geophone 11 than the protective member 14, or closer to the data logger 13.

[0045] The straight section 114 is a section that is not wound in a spiral but is formed in a straight line, and is located on both sides of the slack forming section 113. The cable 112 in the straight section 114 is continuous with the cable 112 at the end of the slack forming section 113. The straight section 114 on the bottom side of the vibration receiving hole 5 is connected to the vibration receiver 11, and the straight section 114 on the opening side of the vibration receiving hole 5 is connected to the data logger 13. Elastic body 115 As shown in FIG. 9 , the straight portions 114, 114 of the cable 112 located on either side of the slack forming portion 113 are connected to each other by an elastic body 115 that can stretch freely. The elastic bodies 115 are formed, for example, from linear rubber members, and are fixed to the ends of the straight portions 114 on either side of the slack forming portion 113. The elastic bodies 115 are formed to a length equivalent to that of the slack forming portion 113 in its contracted state, i.e., its shortest state. When the slack forming portion 113 is pulled, the elastic bodies 115 are stretched together with the slack forming portion 113. When the tension on the slack forming portion 113 is released, the elastic bodies 115 pull the straight portions 114, 114 together, returning the slack forming portion 113 to its original shape.

[0046] When installing the receiver device 110 in the receiver borehole 5, as shown in FIG. 10 , the receiver 11, protective member 14, and data logger 13 are inserted into the receiver borehole 5 in this order. If the receiver 11 is installed in a predetermined position and the data logger 13 is outside the receiver borehole 5, the cable 112 will require more slack than when it was installed. In this embodiment, when the receiver 11 is installed in a predetermined position and the slack forming portion 113 of the cable 112 is pulled, the spiral portion unfolds, allowing the cable to be elongated. This allows the data logger 13 to wait outside the receiver borehole 5. After the protective member 14 is installed, the data logger 13 can be inserted into the opening of the receiver borehole 5. At this time, the straight portions 114, 114 are pulled together by the elastic body 115, and the slack forming portion 113 gradually returns to its original shape, preventing the cable 112 from bending. This allows the cable 112 to be held in the center of the vibration receiving hole 5, preventing the cable 112 from getting caught between the data logger 13 and the vibration receiving hole 5. This reduces the risk of the cable 112 getting caught in equipment or the like and being damaged. In this embodiment, an elastic body 115 is provided inside the slack forming portion 113, so that the slack forming portion 113 can be reliably returned to its original shape. It is also possible to have the original shape restored only by the extra length forming portion 113 without providing the elastic body 115.

[0047] While the embodiments for carrying out the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified as appropriate without departing from the spirit of the present invention. In the above-described embodiments, the exterior material 32 of the protective member 14 is provided over the entire length of the core material 31, but this is not limited to this. A plurality of exterior materials 32 may be provided at intervals in the axial direction of the core material 31. With this configuration, the contact area between the exterior material 32 and the inner surface of the vibration receiving hole 5 can be further reduced, making it even easier to insert the protective member 14 into the vibration receiving hole 5. Furthermore, the soundproofing material 15 is attached by wrapping it around the main body 51 of the data logger 13, but this is not limitative. For example, it may be attached by applying rubber or the like to the outer circumferential surface of the main body 51. With this configuration, the thickness of the soundproofing material 15 can be adjusted according to the shape of the inner circumferential surface of the vibration receiving hole 5. [Explanation of symbols]

[0048] 5 Receiving hole 10 Sound receiver 11 Geophone 12 Cable (signal transmission component) 13 Data logger (recording unit) 14 Protective material 15 Soundproofing materials 24 Holding part 31 Core material 32 Exterior materials 53 Protruding switch (input means) 54 Immersion Switch (Input Method) 100 Push-in member 110 Sound receiver 112 Cable 113 Extra length forming section 114 Straight section 115 Elastic Body

Claims

1. A vibration receiving device installed in a vibration receiving hole drilled in the wall surface of a tunnel, a geophone for detecting elastic waves generated by excavation and blasting; a signal transmission member for transmitting data detected by the geophone; a recording unit for recording the data; a protection member for protecting the signal transmission member; a soundproofing member interposed between the outer peripheral surface of the recording unit and the inner peripheral surface of the vibration receiving hole. A vibration receiving device characterized by:

2. the signal transmission member is a cable, The recording unit is a data logger 2. The vibration receiving device according to claim 1.

3. the protective member has a tubular core material attached to an outer circumferential surface of the cable, and an outer circumferential surface of the core material, The exterior material is made of a material that is softer than the core material.

3. The vibration receiving device according to claim 2.

4. The outer circumferential surface of the exterior material has an uneven shape.

4. The vibration receiving device according to claim 3.

5. At least one of the core material and the exterior material has vibration absorption properties.

4. The vibration receiving device according to claim 3.

6. the cable has a slack forming portion that forms a slack for installing the vibration receiving device in the vibration receiving hole, The extra length forming portion is formed in a spiral shape with an outer diameter smaller than the inner diameter of the vibration receiving hole.

4. The vibration receiving device according to claim 3.

7. The straight portions of the cable located on both sides of the extra length forming portion are connected to each other by an elastic body that is stretchable and retractable, The cable at the extra length forming portion is shortened to the shortest length after the device is installed.

7. The vibration receiving device according to claim 6.

8. The receiver includes a main body and a holding part that extends from the main body and presses against the inner circumferential surface of the receiver hole. The data logger is provided with an input means for causing the holding portion to appear and disappear.

3. The vibration receiving device according to claim 2.

9. a first installation step of inserting a georeceiver that detects elastic waves generated by excavation and a data transmission cable connected to the georeceiver into a georeceiver hole drilled in the tunnel wall surface; an attachment step of attaching a protective member to the cable in the vibration receiving hole; a second installation step of installing a data logger at the opening of the seismic receiving hole, the data logger recording the measurement data detected by the seismic receiver; Before the second installation step, a soundproofing material is attached to the outer periphery of the data logger. A method for installing a seismic receiving device.

10. In the first installation step, by pressing an input means provided on the data logger, a holding part provided on the geophone in a retractable manner is protruded and pressed against the inner wall of the geophone hole, thereby positioning the geophone.

10. The method for installing a vibration receiving device according to claim 9.

11. In the first installation step, the push-in member is fitted to the geophone, the geophone is pushed into the receiving hole, the holding portion is protruded to position the geophone, and then the push-in member is pulled out. The method for installing a vibration receiving device according to claim 10.

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