Method and apparatus for investigating ground condition between tunnels

Abstract

To enable accurate two-dimensional assessment of ground conditions between adjacent tunnels.SOLUTION: A method for investigating ground conditions between adjacent tunnels 10 and 20 comprises: arranging measurement devices 40 and 60 respectively on opposing sidewalls of the adjacent tunnels 10 and 20, each including acoustic sensors 46 and 62 that transmit and receive ultrasonic waves; and detecting acoustic waves propagated between the acoustic sensors 46 and 62.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method and device for investigating ground conditions between tunnels, and in particular to a method and device for investigating ground conditions between tunnels that are suitable for use when investigating the condition of the ground between tunnels when constructing an evacuation passage or the like between adjacent tunnels. [Background technology]

[0002] Investigating and understanding soil properties is important for the safe and economical construction of underground structures such as tunnels.

[0003] Therefore, in tunnel construction, ground surveys such as the results of past ground surveys, elastic wave exploration from the ground surface, and soil tests using drilling are carried out from the investigation and design stages to predict the ground properties.

[0004] However, when there are few past ground survey results or when ground surveys are difficult due to restrictions on the ground surface, it is difficult to accurately grasp the necessary soil properties.

[0005] This is also true in construction work to build a structure such as a connecting passage 30 between two tunnels 10, 20, as seen in road tunnels and subway tunnels, as exemplified in FIG.

[0006] In construction of access roads and other structures, a portion of the tunnel wall must be cut and widened, and the ground in that area must be improved in advance by injecting chemicals, freezing the ground, etc., in order to improve the strength and watertightness of the ground. This ground improvement method is determined by the properties of the target ground, so it is necessary to accurately understand the soil properties.

[0007] This is because if there is ground (defective area) B within the ground improvement area A, as shown in Figure 2, that is difficult for chemicals to penetrate, or ground C that is not suitable for freezing, the effectiveness of the ground improvement will be limited, and there is a risk of accidents such as flooding or ground collapse.

[0008] One method of soil investigation is to drill from above ground.

[0009] In particular, when accurately investigating the joint area, several borings D are made in an approximately horizontal direction from inside the tunnel, as shown in Figure 2.

[0010] Patent Document 1 describes a method for detecting ground collapses or the like at the tunnel face or other parts using ultrasound or the like.

[0011] In addition, Patent Document 2 describes a method in which two boreholes are drilled on both the left and right sides of a tunnel face, one of which is used as a receiving hole and drilled to the depth to be measured, and the other is used as an oscillator hole. The method describes a method in which an impact is applied to an oscillation hole to serve as an oscillation source, an oscillation signal from the oscillation hole is received by a receiving point installed within the receiving hole, and the oscillation time from the oscillation point and the received waveform at the receiving point are measured, thereby determining the distribution of the elastic wave velocity of the ground ahead of the face from the measurement results and making it possible to predict the geology ahead of the face.

[0012] Furthermore, Patent Document 3 describes a technique for detecting the location of an underground structure adjacent to a tunnel using sound waves. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Patent No. 6393100 [Patent Document 2] Patent No. 2817076 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-174505 [Patent Document 4] Japanese Patent Application Publication No. 11-117686 Summary of the Invention [Problem to be solved by the invention]

[0014] However, boring from the surface presents economic problems when drilling to great depths.

[0015] Furthermore, as shown in Figure 2, the method of drilling several holes D in a roughly horizontal direction from inside the tunnel only provides one-dimensional information on the boring lines, making it impossible to conduct a detailed investigation, and there may be gaps in the investigation, making it impossible to improve the defective part B.

[0016] Furthermore, the technology described in Patent Document 1 does not go so far as to grasp the soil classification of the natural ground.

[0017] Furthermore, the technology described in Patent Document 2 cannot be adopted when it is not possible to provide a borehole in an appropriate position due to ground restrictions.

[0018] Furthermore, the technology described in Patent Document 3 has problems such as not being able to survey the ground between tunnels.

[0019] From the above perspective, there was a need for a method to accurately grasp the ground conditions in the ground improvement area A between tunnels as shown in Figure 2.

[0020] The present invention has been made to solve the above-mentioned conventional problems, and its object is to make it possible to accurately grasp the ground conditions between adjacent tunnels on a planar basis. [Means for solving the problem]

[0021] The present invention solves the above problem by installing acoustic sensors that emit and receive ultrasonic waves on the opposing side walls of adjacent tunnels, detecting acoustic waves propagating between the acoustic sensors, and investigating the condition of the ground between the tunnels.

[0022] Here, the acoustic sensor can be disposed in a through hole provided in the side wall of the tunnel.

[0023] Furthermore, the acoustic sensors can first be distributed over the entire opposing side walls of the tunnel to easily investigate the overall condition of the ground between the tunnels, and then, based on the results of the investigation of the overall condition, acoustic sensors can be added to necessary parts of the tunnel side walls to conduct a more detailed investigation.

[0024] Furthermore, the acoustic sensors disposed on both tunnel side walls can be synchronized using a time synchronization system using satellite positioning.

[0025] Furthermore, the acoustic sensors installed on both tunnel side walls can be shifted in the longitudinal direction of the tunnel or deployed horizontally to enable three-dimensional investigation of the ground between the tunnels.

[0026] The present invention also solves the above-mentioned problems by providing an apparatus for investigating the ground between tunnels, which is characterized by comprising acoustic sensors for emitting and receiving ultrasonic waves, which are arranged on the opposing side walls of adjacent tunnels, and means for detecting acoustic waves propagating between the acoustic sensors and investigating the condition of the ground between the tunnels.

[0027] Here, the tunnel may be constructed by a shield method or a jacking method, and the through hole may be formed in a skin plate or a chemical injection hole of the tunnel. [Effects of the Invention]

[0028] According to the present invention, it is possible to accurately grasp the surface properties of the ground between adjacent tunnels. [Brief explanation of the drawings]

[0029] [Figure 1] A perspective view showing an example of a tunnel and connecting shaft installed side by side [Figure 2] Cross section of the connecting tunnel [Figure 3] FIG. 1 is a perspective view showing the overall configuration of an embodiment of the present invention. [Figure 4] A diagram showing the configuration of the measurement device [Figure 5] A block diagram showing the configuration of the signal analyzer. [Figure 6] A diagram showing an example of the placement of the sensor units. [Figure 7] 1A and 1B are a perspective view and a side view, respectively, showing an example of a sensor unit; [Figure 8] FIG. 10 is a perspective view and a side view of another example of the sensor unit. [Figure 9] FIG. 10 is an enlarged cross-sectional view showing the specific configuration of the sensor unit. [Figure 10] A flow chart showing the installation procedure for the sensor unit. [Figure 11] Cross-sectional view corresponding to the installation procedure in Figure 10 [Figure 12] A flowchart showing an example of the investigation procedure. [Figure 13] A cross-sectional view showing the details of the investigation procedure in Figure 12. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the contents described in the following embodiments. Furthermore, the components in the embodiments described below include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the components disclosed in the embodiments described below may be combined as appropriate, or may be selected and used as appropriate.

[0031] The overall structure of an embodiment of the present invention is shown in Fig. 3. This embodiment includes an oscillator measuring device 40 installed in one of the adjacent tunnels 10, a Global Navigation Satellite System (GNSS) antenna (referred to as a GNSS antenna) 50 connected to the oscillator measuring device 40, a receiver measuring device 60 installed in the other of the adjacent tunnels 20, a GNSS antenna 68 connected to the receiver measuring device 60, a signal line 52 connecting the oscillator measuring device 40 and the GNSS antenna 50 via a vertical shaft 11 connecting the tunnel 10 to the ground surface, a signal line 70 connecting the receiver measuring device 60 and the GNSS antenna 68 via a vertical shaft 21 connecting the tunnel 20 to the ground surface, and a signal analyzer 78 that receives signals from the oscillator measuring device 40 and the receiver measuring device 60 via a signal receiving unit 80 and performs the necessary signal processing and analysis.

[0032] As shown in detail in Figure 4, the oscillation side measurement device 40 comprises a signal generator 42 that generates a multiplexed oscillation signal, such as a pseudo-random wave, emitted from an oscillation acoustic sensor (hereinafter referred to as the oscillation sensor) 46, an amplifier 44 that amplifies the output of the signal generator 42 and provides it to the oscillation sensor 46, a signal line 52 that sends the signal generated by the signal generator 42 to a GNSS time synchronization system 48, and a GNSS antenna 50 connected to the GNSS time synchronization system 48.

[0033] As shown in detail in Figure 4, the receiving measuring device 60 also includes a data logger 64 that records the output of the receiving acoustic sensor (hereinafter simply referred to as the receiving sensor) 62, a signal line 70 that sends the received signal recorded by the data logger 64 to a GNSS time synchronization system 66, and a GNSS antenna 68 connected to the GNSS time synchronization system 66.

[0034] For example, a signal analyzer 78 is provided on the ground surface 8, which receives, processes, and analyzes signals from the transmitting-side measuring device 40 and the receiving-side measuring device 60. As shown in detail in Fig. 5, this signal analyzer 78 is equipped with a signal receiving unit 80 including an antenna, a signal demodulation unit 82 which demodulates the received signal, for example, demodulating a pseudo-random wave into a pulse wave, an arrival velocity / amplitude reading unit 84 which reads the arrival velocity and amplitude, an inverse calculation unit 86, and a 2D / 3D data output unit 88, and causes acoustic waves to propagate between the transmitting sensor 46 and the receiving sensor 62, and creates maps of the propagation velocity and amplitude attenuation rate of the acoustic waves, thereby creating accurate maps of the geological structure, etc.

[0035] The signal analysis device 78 does not necessarily have to be placed on the ground surface, but may be placed near the measurement devices 40 and 60. It may also be installed in an office away from the tunnel via the cloud.

[0036] An example of the layout of the sensors 46, 62 is shown in Figure 6. When investigating a horizontal surface, the sensors 46, 62 are installed horizontally as shown in the upper part of Figure 6, and the directivity of the sensor 46 in the sensor unit 200 is aligned with the horizontal plane, as shown in an example of the sensor 46 in Figure 7.

[0037] On the other hand, when investigating the cross-sectional direction, the sensors 46 and 62 are installed in the vertical direction as shown in the lower part of Figure 6, and the directivity of the sensor 46 in the sensor unit 200 is aligned with the cross-section as shown in Figure 8, for example, to obtain two-dimensional (2D) and three-dimensional (3D) information.

[0038] 9, the sensor unit 200 is a cylindrical body having a sensor 202, which serves as the oscillation sensor 46 or the receiving sensor 62, disposed at its front end and a waterproof connector 204 connected to its rear end. The sensor 202 may be a cylindrical sensor with a diameter of approximately 20 mm and a height of approximately 28 mm. A signal line 206, which serves as the signal line 52 or 70, extends from the waterproof connector 204.

[0039] The tip of the sensor unit 200 penetrates the ground, for example, by penetrating the skin plate 12, which is a segment of the tunnels 10 and 20, and is connected to the center by a mouth valve 90 consisting of a main valve 100, for example, a ball valve, a pre-bender 110 with a trapezoidal thread, and a water injection valve 120 connected to the pre-bender 110.

[0040] The pre-bender 110 includes a packing 112, a trapezoidal screw 114, and a water-stopping rubber 116, and after the tunnel is inserted, the trapezoidal screw 114 fits in to ensure water-stopping performance.

[0041] The procedure for installing the sensor unit 200 will be described below with reference to FIG.

[0042] First, in step S1000, as shown in Fig. 11(A), grout holes 14 are installed in the skin plate 12. A resin check valve is built into the grout holes 14, and caps 16 with O-rings are provided.

[0043] Next, in step S1100, as shown in FIG. 11(B), the mouth valve 90, which is composed of the main valve 100, the pre-bender 110, and the water injection valve 120, is attached.

[0044] Next, in step S1200, as shown in Figure 11(C), the check valve, skin plate 12, and backfill layer of natural ground built into the grout hole 14 are removed using a core drill 130 having a diamond pit 132 with a core lifter built into the tip to prevent it from falling out.

[0045] Next, the process proceeds to step S1300, where the sensor unit 200 incorporating the sensor 202, which is the oscillation sensor 46 or the receiving sensor 62, is inserted into the mouth valve 90 and attached, as shown in FIG. 11(D).

[0046] Next, proceed to step S1400, where, as shown in Figure 11(E), the sensor unit 200 is screwed in and fixed, the water injection valve 120 is opened to inject water into the hole, and the signal line 206 is wired to the sensor unit 200. At this time, the packing 112 of the pre-bender 110 seals the water when the sensor unit 200 is inserted, and after insertion, the trapezoidal screw 114 fits in to ensure watertightness. Furthermore, screwing in the sensor unit can improve watertightness and adhesion to the external ground.

[0047] Next, the process proceeds to step S1500, and measurement is performed in the state shown in FIG. 11(F).

[0048] Next, proceed to step S1600, and as shown in Figure 11(G), after pulling out and removing the sensor unit 200, dismantle the mouth valve 90 and install a water stop plug 134 to temporarily stop the water flow until the O-ring cap 16 is restored, and then dismantle the mouth valve 90 into the main valve 100, pre-bender 110, and water inlet valve 120 and remove them.

[0049] Next, the process proceeds to step S1700, where the O-ring cap 16 is attached and restored as shown in FIG. 11(H).

[0050] When conducting an investigation, it would take a long time to conduct a detailed investigation of the entire ground improvement area A from the beginning, so as shown in Figure 12, the investigation procedure is as follows: first, in step S2000, as shown in Figure 13(A), a portion of the oscillation sensor 46, e.g., half, and a portion of the receiving sensor 62, e.g., half, are operated to conduct a rough investigation of the entire ground improvement area A.

[0051] Next, in step S2100, for range E where a problem was found, a detailed investigation is carried out by operating all of the oscillation sensors 46 and all of the receiving sensors 62 within range E, as shown in Fig. 13(B). This allows the necessary investigation to be carried out over the entire range in a shorter amount of time than if a detailed investigation of the entire range were carried out.

[0052] In this embodiment, the installation is easy because the transmission and reception of signals between the oscillation-side measuring device 40 and the receiving-side measuring device 60 and the signal analyzing device 78 are performed wirelessly. However, it is also possible to perform some or all of the transmission and reception of signals between the oscillation-side measuring device 40 and the receiving-side measuring device 60 and the signal analyzing device 78 by wire.

[0053] In this embodiment, multiple oscillations by pseudo-random waves are used, so that the investigation time can be shortened.

[0054] In the above embodiment, a new hole was drilled in the skin plate of the tunnel to conduct the survey, but if a chemical injection hole for injecting a chemical solution into the ground is formed, as shown in Patent Document 4, for example, it is possible to attach the sensor unit using this chemical injection hole. Because the sensor unit 200 in the above embodiment has a small diameter, it can be easily installed in a chemical injection hole that has a restricted outer diameter, and watertightness can be maintained.

[0055] The type of connecting passage 30 is not limited to evacuation purposes, and the ground conditions between tunnels can be investigated for purposes other than connecting passage 30. [Explanation of symbols]

[0056] 10, 20...Tunnel 12...Skin plate 14...Grout hole 30...Connecting passage 40...Oscillation side measurement device 42...Signal generator 46...Oscillation (acoustic) sensor 48, 66...GNSS time synchronization system 50, 68...GNSS antenna 52, 70...Signal wire 60...Receiving side measuring device 62... Receiving (acoustic) sensor 64...Data logger 78...Signal analysis device 80...Signal receiving unit 82...Signal demodulation unit 84... Arrival speed / amplitude reading unit 86...Inverse calculation unit 88...2D / 3D output unit 90...Mouth valve 100...Main valve 110...Pre-bender 120...Water inlet valve 130...Core drill 200...Sensor unit 202...Sensor

Claims

1. Acoustic sensors that emit and receive ultrasonic waves are installed on the opposing side walls of the adjacent tunnels, Detecting an acoustic wave propagating between the acoustic sensors, A method for investigating ground conditions between tunnels, characterized by investigating the condition of the ground between tunnels.

2. 2. The method for investigating ground conditions between tunnels according to claim 1, wherein the acoustic sensor is disposed in a through hole installed in a tunnel side wall.

3. 2. A method for investigating ground properties between tunnels according to claim 1, characterized in that the acoustic sensors are first distributed over the entire opposing side walls of the tunnel to easily investigate the overall condition of the ground between the tunnels, and then, based on the results of the investigation of the overall condition, additional acoustic sensors are added to necessary parts of the tunnel side walls to conduct a detailed investigation.

4. 2. A method for investigating ground conditions between tunnels according to claim 1, characterized in that synchronization between the acoustic sensors arranged on both tunnel side walls is performed using a time synchronization system using satellite positioning.

5. A method for investigating ground properties between tunnels as described in claim 1, characterized in that the acoustic sensors arranged on both tunnel side walls are shifted in the longitudinal direction of the tunnel or deployed horizontally to conduct a three-dimensional investigation of the ground between the tunnels.

6. acoustic sensors for emitting and receiving ultrasonic waves, which are disposed on opposing side walls of the adjacent tunnels; a means for detecting acoustic waves propagating between the acoustic sensors to investigate the condition of the ground between the tunnels; An investigation device for investigating ground conditions between tunnels, characterized by comprising:

7. 7. The device for investigating ground conditions between tunnels according to claim 6, wherein the acoustic sensor is disposed in a through hole provided in a side wall of the tunnel.

8. The device for investigating ground conditions between tunnels as described in claim 7, characterized in that the tunnel is constructed using a shield method or a jacking method, and the through hole is formed in the skin plate or chemical injection hole of the tunnel.

9. The device for investigating ground conditions between tunnels as described in claim 6, characterized in that it is equipped with a time synchronization system using satellite positioning to synchronize the acoustic sensors arranged on both tunnel side walls.

10. The device for investigating ground properties between tunnels described in claim 6, characterized in that the acoustic sensors arranged on both tunnel side walls are shifted in the longitudinal direction of the tunnel or deployed horizontally so as to conduct a three-dimensional investigation of the ground between the tunnels.

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