JP5679804B2 - Geological exploration system - Google Patents

Description

  The present invention relates to a geological exploration system that performs geological exploration during tunnel excavation and the like.

  In mountain tunnel construction and urban shield tunnel construction, if there is a soft stratum such as a fault crush zone in front of the face, it is necessary to change the support pattern, reinforce or improve the ground prior to tunnel excavation, etc. In order to carry out tunnel excavation safely and rationally, it is necessary to investigate the geological conditions ahead of the tunnel face in advance and grasp it with high accuracy.

  For this reason, conventionally, as means for exploring the geology in front of the face, refraction method elastic wave exploration using the refracted wave of the elastic wave oscillated from the ground surface, and reflected wave using the reflected wave of the elastic wave oscillated from the face Elastic wave exploration is performed (see Patent Document 1).

  Refraction seismic exploration is effective for understanding the formation of the strata, but is not suitable for understanding low-velocity layers such as fault fracture zones that affect tunneling, and the deeper the covering, Exploration reliability decreases.

  In addition, reflection seismic exploration can grasp the position of geological discontinuities such as fault fracture zones, but it is difficult to grasp the degree of geological hardness, so it is It is difficult to distinguish between a soft part such as a fault fracture zone and a hard part that is a high-velocity layer, and the fault fracture zone existing in front of the face cannot be grasped with high accuracy. In particular, in a low earth covering environment, elastic waves are reflected even on the ground surface, so the accuracy of geological analysis is significantly reduced.

  Therefore, in recent years, an exploration technique using a direct wave of an elastic wave oscillated from a face has been considered so that the degree of geological hardness can be grasped (see Patent Document 1).

  In this exploration method, a direct wave of an elastic wave oscillated from an oscillation point is received at the receiving point, and the propagation velocity of this elastic wave is analyzed by tomography, so that the geological structure of the section cut through the ground is grasped. is there.

JP 2003-014863 A

  However, since the conventional exploration method is a two-dimensional exploration, it was only possible to analyze the geological structure of a section cut from a natural ground. For this reason, if a high-speed layer that is harder than the cross-section to be analyzed exists at a position off the cross-section to be analyzed, the refracted wave or reflected wave from the high-speed layer is observed at the receiving point before direct observation of the elastic wave Since waves are observed as the initial motion, the accuracy of tomographic analysis is reduced, and there is a problem that the degree of geological hardness in front of the face cannot be properly grasped.

  Then, an object of this invention is to provide the geological exploration system which can grasp | ascertain the degree of hardness of the geology ahead of a face with high precision.

The geological exploration system according to the present invention is a geological exploration system for exploring the geology in front of the face of a tunnel excavated based on the propagation time of elastic waves, and includes an elastic wave oscillating means for oscillating elastic waves, and an elastic wave oscillating means An oscillation time detecting means for detecting an oscillation time at which an elastic wave is oscillated from, an elastic wave receiving means for receiving an elastic wave, a receiving time detecting means for detecting a receiving time when the elastic wave receiving means receives an elastic wave, and an oscillation Tunneling using tomographic analysis from the propagation time of elastic waves from the elastic wave oscillation means to the elastic wave reception means calculated based on the oscillation time detected by the time detection means and the vibration reception time detected by the vibration reception time detection means The analysis means for generating the elastic wave velocity distribution ahead of the face of the face, the oscillation time detected by the oscillation time detection means and the vibration reception time detected by the vibration reception time detection means are aligned on the same time axis. And either one of the elastic wave oscillating means or the elastic wave receiving means is disposed in the tunnel pit, and either the elastic wave oscillating means or the elastic wave receiving means is disposed on the ground surface in front of the face. A plurality of two-dimensional or three-dimensional arrangements are made, and the oscillation time detecting means and the receiving time detecting means are arranged at either the tunnel tunnel where the elastic wave receiving means is arranged or the ground surface in front of the face and the same time. When the elastic wave is oscillated from the elastic wave oscillating means, the synchronizing means is a radio transmission means arranged in either the tunnel pit where the elastic wave oscillating means is arranged or the ground surface in front of the face Thus, the trigger signal is wirelessly transmitted to the oscillation time detecting means and the vibration receiving time acquiring means, and the oscillation time detecting means sets the reception timing of the trigger signal to the oscillation time when the elastic wave is oscillated from the elastic wave oscillating means .
According to the geological exploration system of the present invention, the elastic wave oscillating means and the elastic wave receiving means are arranged separately in the tunnel pit and the ground surface in front of the face, so that the elastic wave detected by the oscillation time detecting means The propagation speed of the elastic wave can be measured from the oscillation time and the elastic wave receiving time detected by the receiving time detecting means. And, by arranging a plurality of two-dimensionally or three-dimensionally either the elastic wave oscillating means or the elastic wave receiving means on the ground surface part in front of the face, the propagation path of the elastic wave in front of the face can be increased. In addition, since the three-dimensional elastic wave velocity distribution can be generated by the analysis means, the degree of hardness of the geology in front of the face can be grasped with high accuracy in consideration of the surrounding geological condition. The accuracy of tomography analysis can be improved by synchronizing the time axes of the oscillation time detecting means and the vibration receiving time detecting means. Since the oscillation time detection means and the vibration reception time detection means have the same time information, the time axes of the oscillation time detection means and the vibration reception time detection means can be matched, and an elastic wave oscillates from the elastic wave oscillation means. This is notified to the oscillation time detecting means and the vibration receiving time detecting means by wireless transmission of a trigger signal, so that the timing at which the elastic wave is oscillated from the elastic wave oscillating means in the oscillation time detecting means and the vibration receiving time detecting means is substantially real time. Can know. Thereby, the propagation time of the elastic wave from the elastic wave oscillating means to the elastic wave receiving means can be calculated with high accuracy.

And it is preferable that a vibration receiving time detection means will start the detection of the vibration receiving time when an elastic wave receiving means receives an elastic wave, if a trigger signal is received. In this way, the vibration receiving time detecting means starts detecting the vibration receiving time after receiving the trigger signal, so that the elastic wave from the elastic wave oscillating means to the elastic wave receiving means is detected only by the vibration receiving time detected by the vibration receiving time detecting means. Wave propagation time can be calculated with high accuracy.
In these cases, it is preferable that any one of the elastic wave oscillating means and the elastic wave receiving means is arranged in the tunnel mine. As described above, since a plurality of either the elastic wave oscillating means or the elastic wave receiving means can be arranged in the tunnel well, the propagation path of the elastic wave in front of the face can be greatly increased. The degree of hardness can be grasped with higher accuracy.

  According to the present invention, the degree of geological hardness in front of the face can be grasped with high accuracy.

It is a longitudinal section showing the geological exploration system concerning a 1st embodiment. It is the top view which showed the example of arrangement | positioning of an elastic wave receiving device. It is the figure which showed the example of a recording of the waveform and time information by a waveform acquisition apparatus. It is the flowchart which showed the procedure of three-dimensional tomography analysis. It is a longitudinal cross-sectional view which shows the geological exploration system which concerns on 2nd Embodiment. It is a longitudinal cross-sectional view which shows the geological exploration system which concerns on 3rd Embodiment. It is a longitudinal cross-sectional view which shows the geological exploration system which concerns on 4th Embodiment. It is a longitudinal cross-sectional view which shows the geological exploration system which concerns on 5th Embodiment. The elastic wave velocity distribution which is a simulation result of the comparative example is shown. The elastic wave velocity distribution which is the simulation result of an Example is shown.

  Hereinafter, a preferred embodiment of a geological exploration system according to the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

[First Embodiment]
FIG. 1 is a longitudinal sectional view showing a geological exploration system according to the first embodiment. As shown in FIG. 1, the geological exploration system 1 according to the present embodiment calculates the propagation speed of elastic waves between the tunnel A mine and the ground surface in front of the face before excavating the tunnel A. Investigate the degree of geological hardness in front of the face. In addition, as shown in FIG. 1, the fault crushing zone B which is a low-velocity layer exists in front of the face of the tunnel A.

  The geological exploration system 1 is detected by an oscillation-side facility 10 for oscillating an elastic wave in the tunnel A mine, a vibration-receiving facility 20 for receiving an elastic wave that has reached the ground surface in front of the face, and an oscillation-side facility 10. And an analysis computer 30 for grasping the degree of geological hardness in front of the face based on the detected information and the information detected by the receiving side equipment 20.

  The oscillation side equipment 10 includes an elastic wave oscillation device 11, an oscillation time detection device 12, a time information reception device 13, an optical transmission line 14, and a clock device 15.

  The elastic wave oscillating device 11 is an oscillation point that is arranged on a face in the tunnel A mine and oscillates an elastic wave toward the front of the face. The elastic wave oscillating device 11 is composed of, for example, a hammer or a mechanical oscillator (for example, an electromagnetic hammer, a hydraulic impactor, a vibrator) or the like. Usually, when digging through the tunnel A, it blasts with a face about four times a day. Therefore, it is preferable to apply this blasting to the elastic wave oscillator 11. In a low earth covering environment of about 10 to 20 m, an elastic wave oscillated by a hammer or a mechanical oscillator is transmitted to the ground surface. In a high earth covering environment of 100 m or more, high energy such as blasting is generated. Since elastic waves are not transmitted to the ground surface unless elastic waves are generated, it is also preferable to determine means used for the elastic wave oscillation device 11 according to the degree of covering.

  The oscillation time detection device 12 is arranged in the vicinity of the face in the tunnel A well like the elastic wave oscillation device 11 and detects the oscillation time of the elastic wave oscillated from the elastic wave oscillation device 11. That is, the oscillation time detection device 12 includes an internal clock (not shown) and an initial motion detection sensor (not shown) that detects the initial motion of the elastic wave oscillated from the elastic wave oscillation device 11. The oscillation time detection device 12 detects the oscillation time of the elastic wave oscillated from the elastic wave oscillation device 11 by recording the time of the internal clock when the initial motion detection sensor detects the initial motion of the elastic wave. Note that the oscillation time detection device 12 includes, for example, a vibration measurement device that measures vibration, and records the vibration waveform measured by the vibration measurement device together with the time information of the internal clock, and generates an elastic wave from the recorded waveform. It is also possible to detect the oscillation time of the elastic wave oscillated from the elastic wave oscillating device 11 by detecting the initial movement.

  The time information receiving device 13 is arranged outside the tunnel A mine and receives time information transmitted from a time information transmitting device (not shown). The time information transmitter is, for example, a GPS (Global Positioning System) satellite (not shown) or a standard frequency time signal station (not shown). The time information receiver 13 is, for example, GPS information transmitted from a GPS satellite. A receiver for receiving GPS time information included in the receiver, a receiver for receiving standard time information included in a standard radio wave transmitted from a standard frequency information station, and the like.

  The optical transmission line 14 includes an optical fiber cable 14a extending in the tunnel A pit, an optical transmitter 14b connected to one end of the optical fiber cable 14a and connected to the time information receiver 13, and an optical fiber cable 14a. And an optical receiver 14c connected to the clocking device 15 and connected to the other end of the clock. When the time information receiver 13 receives the time information, the optical transmitter 14b optically transmits the time information to the optical receiver 14c through the optical fiber cable 14a. For this reason, the clocking device 15 arranged in the tunnel A mine can acquire the time information received by the time information receiving device 13 in substantially real time.

  The clocking device 15 is connected to the oscillation time detection device 12 in the tunnel A mine, and synchronizes the internal clock of the oscillation time detection device 12 with the received time information. Thereby, the oscillation time detection device 12 can detect the oscillation time of the elastic wave oscillated by the elastic wave oscillation device 11 based on the time information transmitted from the time information transmission device. When the time information receiving device 13 receives GPS time information transmitted from a GPS satellite, it is possible to detect the oscillation time of the elastic wave oscillated by the elastic wave oscillating device 11 with reference to this GPS time information. When the time information receiving device 13 receives the standard time information transmitted from the standard frequency time signal station, it is possible to detect the oscillation time of the elastic wave oscillated by the elastic wave oscillating device 11 with reference to the standard time information. .

  The receiving side equipment 20 includes a plurality of elastic wave receiving devices 21 (21 a to 21 f), a waveform acquisition device 22, a time information receiving device 23, and a clocking device 24. The elastic wave receiving devices 21a to 21f all have the same configuration, and will be described below as the elastic wave receiving device 21 unless otherwise specified.

  The elastic wave receiving device 21 is disposed on the ground surface in front of the face and receives the elastic wave oscillated from the elastic wave oscillating device 11 of the oscillation side equipment 10 by measuring the vibration propagated from the tunnel A tunnel. It is. The elastic wave receiving device 21 can transmit the measured vibration waveform to the waveform acquiring device 22.

  FIG. 2 is a plan view showing an arrangement example of the elastic wave receiving device. As shown in FIG. 2, the elastic wave receiving device 21 is two-dimensionally (planarly) or three-dimensionally (three-dimensionally) dispersedly arranged on the surface of the tunnel A in front of the face. That is, the elastic wave receiving devices 21 are not arranged linearly only in the tunnel A digging direction, but are arranged in the tunnel A traveling direction, and also in the direction orthogonal to the tunnel A digging direction. Be placed. The elastic wave receiving device 21 does not necessarily have to be arranged as shown in FIG. 2, but is appropriately arranged at an optimal position according to the shape of the ground surface, the environment, and the like.

  The waveform acquisition device 22 is a data logger that is arranged on the ground surface in front of the face like the elastic wave receiving device 21 and records the waveform of the elastic wave received by each elastic wave receiving device 21. That is, the waveform acquisition device 22 includes an internal clock (not shown) and a plurality of channels (not shown) to which the elastic wave receiving devices 21 are connected. Then, the waveform acquisition device 22 acquires the vibration waveform transmitted from each elastic wave receiving device 21 through each channel, and records the vibration waveform and the time information of the internal clock together. Therefore, by detecting the initial motion of the elastic wave from the recorded waveform and comparing the detected initial motion with the recorded time information, it is possible to obtain the receiving time of the elastic wave received by each elastic wave receiving device 21. It becomes.

  FIG. 3 is a diagram showing a recording example of the waveform and time information by the waveform acquisition device 22. In FIG. 3, the receiving point a is a recording of the waveform transmitted from the elastic wave receiving device 21a, the receiving point b is a recording of the waveform transmitted from the elastic wave receiving device 21b, and the time t is a recording of time information. . Thus, since the waveform transmitted from each elastic wave receiving device 21 and the time information are recorded together, each waveform can be easily compared with the time information. By detecting the initial motion, it is possible to easily obtain the receiving time of the elastic wave received by each elastic wave receiving device 21.

  The time information receiving device 23 is arranged in the vicinity of the clocking device 24 and receives time information transmitted from a time information transmitting device (not shown). The time information transmitting device is, for example, a GPS satellite (not shown) or a standard frequency time signal station (not shown). The time information receiving device 23 is, for example, the same as the time information receiving device 13 of the oscillation side equipment 10, for example. , A receiving device that receives GPS time information included in GPS information transmitted from a GPS satellite, and a receiving device that receives standard time information included in standard radio waves transmitted from a standard frequency reporting station.

  The clocking device 24 is connected to the time information receiving device 23 and the waveform acquisition device 22, and synchronizes the internal clock of the waveform acquisition device 22 with the time information received by the time information receiving device 23. As a result, the waveform acquisition device 22 uses the time information transmitted from the time information transmitting device as a reference in the same manner as the time information receiving device 13 of the oscillation-side equipment 10, and determines the receiving time of the elastic wave received by each elastic wave receiving device 21. The oscillation time detection device 12 and the waveform acquisition device 22 can be aligned on the same time axis. When the time information receiving device 23 receives GPS time information transmitted from a GPS satellite, it is possible to detect the receiving time of the elastic wave received by each elastic wave receiving device 21 with reference to this GPS time information. When the time information receiving device 23 receives the standard time information transmitted from the standard frequency time signal station, the receiving time of the elastic wave received by each elastic wave receiving device 21 is detected based on the standard time information. Can do.

  The analysis computer 30 is disposed at an arbitrary position such as a building office and analyzes the degree of hardness of the geology in front of the face. That is, the analysis computer 30 determines the elasticity based on the oscillation time of the elastic wave detected by the oscillation time detection device 12 and the vibration wave reception time obtained from each waveform and time information recorded by the waveform acquisition device 22. The propagation speed of the elastic wave from the wave oscillating device 11 to each elastic wave receiving device 21 is calculated. And the analysis computer 30 produces | generates the elastic wave velocity distribution ahead of a face by tomography analysis from each propagation velocity, and displays the result on a display etc.

  As described above, since each elastic wave receiving device 21 is arranged two-dimensionally or three-dimensionally, the propagation path of each elastic wave from the elastic wave oscillating device 11 to each elastic wave receiving device 21 is three-dimensional. It is expressed. Therefore, the analysis computer 30 performs a three-dimensional tomography analysis from the propagation velocity of the elastic wave in each propagation path, and generates a three-dimensional elastic wave velocity distribution.

  The analysis computer 30 may acquire the elastic wave oscillation time and the elastic wave receiving record from the oscillation time detection device 12 and the waveform acquisition device 22 by wireless communication or wired communication, and a storage storing these information. The operator may carry the medium to acquire the elastic wave oscillation time and the elastic wave receiving record from the oscillation time detection device 12 and the waveform acquisition device 22. Further, since the position coordinates of the elastic wave oscillation device 11 and the elastic wave receiving devices 21 are necessary in calculating the propagation speed of each elastic wave, it is preferable to obtain these position coordinates in advance.

  Here, the three-dimensional tomography analysis by the analysis computer 30 will be described in detail.

  In the conventional two-dimensional tomographic analysis, it is difficult to obtain accurate results when the underground structure changes three-dimensionally. In addition, in order to conduct high-accuracy exploration, it is necessary to set a cross section that is not easily affected by the three-dimensional structure, which is not suitable for evaluating the geology ahead of the tunnel face as in the present invention.

  Therefore, in the three-dimensional tomography analysis by the analysis computer 30, the Eikonal equation (a finite difference approximation of the wave equation) is improved, and the correction amount of the slowness (Slowness) of each elastic wave line is weighted and averaged. The modified SIRT method (iterative reconstruction method) is used to obtain the correction amount of the grid slowness. Then, the iterative calculation is performed until the propagation path of the elastic wave obtained by the calculation matches the measured propagation path.

ここで、ｔ_Ｌは、弾性波発振装置１１から各弾性波受振装置２１に至る弾性波の伝播時間、Ｌは、弾性波発振装置１１から各弾性波受振装置２１に至る距離、Ｖは、各格子を通る弾性波の伝播速度である。 First, the wave of the measured elastic wave passing through a certain lattice is expressed by the following equation (1).

Here, t _L is the propagation time of the elastic wave from the elastic wave oscillator 11 to each elastic wave receiver 21, L is the distance from the elastic wave oscillator 11 to each elastic wave receiver 21, and V is each It is the propagation speed of elastic waves through the lattice.

ここで、Ｓｉは、各節点におけるスローネス、ｔｃ及びＬｃは、計算された波動の伝播時間及び距離、Ｇａｕｓｓ_Ｒは、ガウスの確率分布、Ｍｉｎ_Ｄは、ある格子Ｐｎと波動Ｌとの距離である。 In general, the propagation path of the elastic wave is not a straight line, but rather is greatly curved due to the density difference between the ground layers. Therefore, the propagation path is assumed to follow the velocity model shown in the following equation (2).

Here, Si is the slowness at each node, tc and Lc are the propagation time and distance of the calculated wave, Gauss _R is the Gaussian probability distribution, and Min _D is the distance between a certain lattice Pn and the wave L. .

  Under these conditions, a three-dimensional tomography analysis is performed according to the procedure shown in FIG. FIG. 4 is a flowchart showing the procedure of three-dimensional tomography analysis.

  As shown in FIG. 4, first, in step S1, an analysis range and analysis accuracy are set, and a mesh is created. Since the analysis accuracy depends on the lattice spacing, the analysis accuracy and calculation conditions are comprehensively determined, for example, a mesh with a 1.0 m interval is used.

  Next, in step S2, appropriate waveforms are extracted from all the waveforms (see FIG. 3) recorded by the waveform acquisition device 22, and filtering for removing noise is performed. This filtering is performed mainly by emphasizing the necessary frequency band and cutting the unnecessary frequency band and restoring the attenuated waveform.

  Next, in step S <b> 3, the initial motion of each waveform recorded by the waveform acquisition device 22 is picked up to obtain the reception time at which each elastic wave receiving device 21 receives the elastic wave, and each elastic wave receiving from the elastic wave oscillating device 11. The propagation velocity of each elastic wave reaching the device 21 is calculated.

  Next, in step S4, an initial elastic wave velocity model (see FIG. 10) in front of the face that is the analysis target range is constructed from the propagation velocity of each elastic wave calculated in step S3. At this time, if significant features (position, elastic wave velocity, etc.) such as stratum boundaries and faults are predicted from the preliminary geological survey results, the information is also included in the initial elastic wave velocity model, so that the accuracy can be further improved. High exploration is possible.

  Next, in step S5, the propagation time of each elastic wave from the elastic wave oscillator 11 to each elastic wave receiver 21 is calculated using the initial elastic wave velocity model constructed in step S4. The calculation is repeated until the calculated propagation time approaches the measurement time recorded by the waveform acquisition device 22.

  Next, in step S6, an elastic wave velocity distribution, which is three-dimensional data, is generated from the calculation result of step S5, and the three-dimensional elastic wave velocity distribution is displayed on a display or the like. If necessary, various conditions are reset as appropriate, and the process returns to step S4 to perform reanalysis.

  Then, by referring to the three-dimensional elastic wave velocity distribution displayed on the display, the degree of geological hardness in front of the face can be grasped. For example, the position of the fault crush zone B, which is the low-velocity layer, and the hardness The degree of propagation (elastic wave propagation velocity) can be grasped.

  As described above, according to the first embodiment, the elastic wave oscillator 11 and the elastic wave receivers 21 are arranged separately in the tunnel A pit and the ground surface in front of the face. The propagation speed of the elastic wave can be measured from the oscillation time of the elastic wave detected by the waveform acquisition unit and each receiving time of the elastic wave obtained from each waveform and time information recorded by the waveform acquisition device 22. Further, by arranging a plurality of elastic wave receiving devices 21 two-dimensionally or three-dimensionally on the ground surface in front of the face, the propagation path of the elastic wave in front of the face can be increased, and the analysis computer 30 performs a third order. Since the original elastic wave velocity distribution can be generated, the degree of hardness of the geology in front of the face can be grasped with high accuracy while considering the surrounding geological condition.

  In addition, by arranging the oscillation time detection device 12 in the tunnel A mine and arranging the waveform acquisition device 22 on the ground surface in front of the face, the oscillation time of the elastic wave and the vibration reception time of the elastic wave can be detected in real time. . Since the time axis of the oscillation time detection device 12 and the waveform acquisition device 22 is synchronized by the time information transmitted from the time information transmission device, the error on the time axis between the oscillation time and the vibration reception time of the elastic wave is minimized. Can be. Thereby, the propagation time of the elastic wave from the elastic wave oscillator 11 to the elastic wave receiver 21 can be calculated with high accuracy.

[Second Embodiment]
Next, a geological exploration system according to the second embodiment will be described. FIG. 5 is a longitudinal sectional view showing a geological exploration system according to the second embodiment. As shown in FIG. 5, the geological exploration system 2 according to the second embodiment is basically the same as the geological exploration system 1 according to the first embodiment, and a plurality of elastic wave oscillators 11 are arranged. Only the difference. For this reason, in the following description, only the part different from the first embodiment will be described, and the description of the same part as the first embodiment will be omitted.

  The oscillation-side equipment 10 of the geological exploration system 2 includes a plurality of elastic wave oscillation devices 11 (11a to 11c), and the oscillation time detection device 12 is an oscillation time of an elastic wave oscillated from each elastic wave oscillation device 11. Is detected. The elastic wave oscillator 11 only needs to be able to oscillate an elastic wave from a different location. For this reason, it is not always necessary to physically prepare a plurality of elastic wave oscillators 11, and the same elastic wave oscillator 11 may oscillate elastic waves from different locations at different times. As described above, since the working face advances as the tunnel A is dug, the position where blasting is performed moves with the passage of time. Therefore, blasting that is performed a plurality of times at different times at different times may be used as each elastic wave oscillator 11. Each elastic wave oscillator 11 is preferably arranged two-dimensionally (planarly) or three-dimensionally (three-dimensionally), but may be arranged linearly.

  The oscillation time detecting device 12 detects the oscillation time of the elastic wave oscillated from each elastic wave oscillating device 11, and the waveform acquisition device 22 of the receiving side equipment 20 is the elastic wave oscillated from each elastic wave oscillating device 11. For each wave, the waveform transmitted from each elastic wave receiving device 51 and the time information of the internal clock are recorded together.

  Then, the analysis computer 30 is based on the oscillation time of each elastic wave detected by the oscillation time detection device 12 and the vibration wave reception time obtained from each waveform and time information recorded by the waveform acquisition device 22. The propagation speed of the elastic wave from each elastic wave oscillator 11 to each elastic wave receiver 21 is calculated.

  At this time, the analysis computer 30 stores the calculated propagation speed of the elastic wave and various information detected this time. That is, when an elastic wave is oscillated by blasting, each time blasting is performed, the oscillation time of each elastic wave detected by the oscillation time detection device 12, each waveform and time information recorded by the waveform acquisition device 22, and the elastic wave This is reflected when the elastic wave is oscillated by the next blast.

  Then, the analysis computer 30 adds the information accumulated to the propagation velocity of the elastic wave calculated this time, generates an elastic wave velocity distribution in front of the face by tomography analysis, and displays the result on a display or the like. The analysis method by the analysis computer 30 is the same as that in the first embodiment.

  As described above, a plurality of elastic wave oscillators 11 are arranged in the tunnel A tunnel, and the tomographic analysis including past accumulated information is performed to greatly increase the propagation path of the elastic wave in front of the face. Therefore, the degree of geological hardness in front of the face can be grasped with higher accuracy.

[Third Embodiment]
Next, a geological exploration system according to the third embodiment will be described. FIG. 6 is a longitudinal sectional view showing a geological exploration system according to the third embodiment. As shown in FIG. 6, the geological exploration system 3 according to the third embodiment is basically the same as the geological exploration system 1 according to the first embodiment, and the arrangement of the oscillation side equipment and the receiving side equipment is switched. Is different. For this reason, in the following description, only the part different from the first embodiment will be described, and the description of the same part as the first embodiment will be omitted.

  The geological exploration system 3 is detected by an oscillation side equipment 40 for oscillating an elastic wave at the surface part in front of the face, a vibration receiving side equipment 50 for receiving an elastic wave reaching the tunnel A tunnel, and the oscillation side equipment 40. And an analysis computer 30 for grasping the degree of geological hardness in front of the face based on the detected information and the information detected by the receiving side equipment 50.

  The oscillation-side facility 40 includes an elastic wave oscillation device 41 (41a to 41f), an oscillation time detection device 42, a time information reception device 43, and a clock device 44. The elastic wave oscillating devices 41a to 41f move one elastic wave oscillating device 41 to generate elastic waves at a plurality of points. However, the elastic wave oscillating devices 41 are arranged at a plurality of points to be elastic. A wave may be generated. Even in the latter case, since the elastic wave oscillators 41a to 41f all have the same configuration, the following description will be made as the elastic wave oscillator 41 unless otherwise specified.

  The elastic wave oscillating device 41 oscillates an elastic wave from the ground surface in front of the face toward the tunnel A, and is distributed two-dimensionally (planarly) or three-dimensionally (three-dimensionally) in the ground part in front of the face. Be placed. That is, each elastic wave oscillator 41 is not arranged linearly only in the tunnel A digging direction, like each elastic wave receiving device 21 of the first embodiment shown in FIG. A plurality are arranged in the traveling direction, and a plurality are also arranged in a direction orthogonal to the tunnel A digging direction.

  The oscillation time detection device 42 is arranged on the ground surface in front of the face like the elastic wave oscillation device 41 and detects the oscillation time of the elastic wave oscillated from each elastic wave oscillation device 41. That is, the oscillation time detection device 42 includes an internal clock (not shown) and a plurality of initial motion detection sensors (not shown) that detect the initial motion of the elastic wave oscillated from each elastic wave oscillation device 41. Then, the oscillation time detection device 42 detects the oscillation time of the elastic wave oscillated from each elastic wave oscillation device 41 by recording the time of the internal clock when each initial motion detection sensor detects the initial motion of the elastic wave. To do.

  The time information receiving device 43 is arranged in the vicinity of the clocking device 44 and receives time information transmitted from a time information transmitting device (not shown). The time information transmitter is, for example, a GPS satellite (not shown) or a standard frequency time signal station (not shown), and the time information receiver 43 is, for example, a GPS time included in GPS information transmitted from a GPS satellite. It is a receiving device that receives information or a receiving device that receives standard time information included in a standard radio wave transmitted from a standard frequency reporting station.

  The clock device 44 is connected to the time information receiver 43 and the oscillation time detector 42, and synchronizes the internal clock of the oscillation time detector 42 with the time information received by the time information receiver 43. Thereby, the oscillation time detecting device 42 can detect the oscillation time of the elastic wave oscillated by the elastic wave oscillating device 41 with reference to the time information transmitted from the time information transmitting device. In addition, when the time information receiver 43 receives GPS time information transmitted from a GPS satellite, it is possible to detect the oscillation time of the elastic wave oscillated by the elastic wave oscillator 41 with reference to this GPS time information. When the time information receiving device 43 receives the standard time information transmitted from the standard frequency time information station, the oscillation time of the elastic wave oscillated by the elastic wave oscillating device 41 can be detected based on the standard time information. .

  The receiving side equipment 50 includes an elastic wave receiving device 51, a waveform acquisition device 52, a time information receiving device 53, an optical transmission path 54, and a clock device 55.

  The elastic wave receiving device 51 is disposed in the vicinity of the face in the tunnel A mine, detects a vibration propagating through the ground, and receives an elastic wave oscillated from each elastic wave oscillating device 41 of the oscillation side equipment 40. It is. The elastic wave receiving device 51 can transmit the measured vibration waveform to the waveform acquisition device 52. It is desirable to install a plurality of elastic wave receiving devices 51 in the vicinity of the face.

  The waveform acquisition device 52 is a data logger that is disposed in the vicinity of the face in the tunnel A pit, similarly to the elastic wave receiving device 51, and records the waveform of the elastic wave received by the elastic wave receiving device 51. That is, the waveform acquisition device 52 includes an internal clock (not shown) and is connected to the elastic wave receiving device 51. Then, the waveform acquisition device 52 records the vibration waveform transmitted from the elastic wave receiving device 51 and the time information of the internal clock together. Therefore, an elastic wave receiving device is detected for each elastic wave oscillated from each elastic wave oscillator 41 by detecting the initial motion of the elastic wave from the recorded waveform and comparing the detected initial motion with the recorded time information. It is possible to obtain the receiving time of the elastic wave received by 51.

  The time information receiving device 53 is arranged outside the tunnel A mine and receives time information transmitted from a time information transmitting device (not shown). The time information transmitting device is, for example, a GPS satellite (not shown) or a standard frequency time signal station (not shown), and the time information receiving device 53 is similar to the time information receiving device 43 of the oscillation side equipment 40, for example. , A receiving device that receives GPS time information included in GPS information transmitted from a GPS satellite, and a receiving device that receives standard time information included in standard radio waves transmitted from a standard frequency reporting station.

  The optical transmission line 54 includes an optical fiber cable 54a extending in the tunnel A tunnel, an optical transmitter 54b connected to one end of the optical fiber cable 54a and connected to the time information receiver 53, and an optical fiber cable 54a. And an optical receiver 54c connected to the timing device 55. When the time information receiver 53 receives the time information, the optical transmitter 14b optically transmits the time information to the optical receiver 14c through the optical fiber cable 14a. For this reason, the timing device 55 arranged in the tunnel A mine can acquire the time information received by the time information receiving device 53 in substantially real time.

  The clock device 55 is connected to the waveform acquisition device 52 in the tunnel A mine, and synchronizes the internal clock of the waveform acquisition device 52 with the received time information. Thereby, the waveform acquisition device 52 detects the receiving time of the elastic wave received by the elastic wave receiving device 51 on the basis of the time information transmitted from the time information transmitting device in the same manner as the time information receiving device 53 of the oscillation side equipment 40. The oscillation time detection device 42 and the waveform acquisition device 52 can be aligned on the same time axis. When the time information receiving device 53 receives GPS time information transmitted from a GPS satellite, it is possible to detect the receiving time of the elastic wave received by the elastic wave receiving device 51 with reference to this GPS time information. When the time information receiving device 53 receives standard time information transmitted from the standard frequency time signal station, it is possible to detect the receiving time of the elastic wave received by the elastic wave receiving device 51 with reference to the standard time information. .

  Then, the analysis computer 30 is based on the oscillation time of each elastic wave detected by the oscillation time detection device 42 and the vibration wave reception time obtained from each waveform and time information recorded by the waveform acquisition device 52. The propagation speed of the elastic wave from each elastic wave oscillation device 41 to the elastic wave receiving device 51 is calculated. And the analysis computer 30 produces | generates the elastic wave velocity distribution ahead of a face by tomography analysis from each propagation velocity, and displays the result on a display etc. The analysis method by the analysis computer 30 is the same as that in the first embodiment.

  Thus, even if the elastic wave oscillation device and the elastic wave receiving device are interchanged, the propagation path of the elastic wave is the same as in the case of the first embodiment. The degree of hardness can be grasped with high accuracy.

[Fourth Embodiment]
Next, a geological exploration system according to the fourth embodiment will be described. FIG. 7 is a longitudinal sectional view showing a geological exploration system according to the fourth embodiment. As shown in FIG. 7, the geological exploration system 4 according to the fourth embodiment is basically the same as the geological exploration system 1 according to the first embodiment, and only the time synchronization method is different. For this reason, in the following description, only the part different from the first embodiment will be described, and the description of the same part as the first embodiment will be omitted.

  The oscillation side equipment 10 includes an elastic wave oscillation device 11, an oscillation time detection device 12, and an underground radio transmission device 61.

  The underground radio transmission device 61 is connected to the oscillation time detection device 12 in the tunnel A tunnel, and performs underground radio communication using a low-frequency radio wave.

  Then, when the initial time of the elastic wave is detected by an initial motion detection sensor or the like, the oscillation time detection device 12 transmits a trigger signal from the underground radio transmission device 61 toward the ground surface in front of the face by underground radio. This trigger signal may be an oscillation time of an elastic wave or a simple pulse signal.

  The receiving side equipment 20 includes a plurality of elastic wave receiving devices 21 (21 a to 21 f), a waveform acquisition device 22, and an underground radio receiving device 62.

  The underground radio receiving device 62 is connected to the waveform acquisition device 22 at the ground surface in front of the face, receives a trigger signal transmitted from the underground radio transmission device 61 by underground radio, and transmits it to the waveform acquisition device 22. To do.

  When the waveform acquisition device 22 receives the trigger signal from the underground radio reception device 62, the time of the internal clock at the time when the trigger signal is received is set as the oscillation time when the elastic wave is oscillated from the elastic wave oscillation device 11. Record. That is, since the underground radio by the underground radio transmission device 61 and the underground radio reception device 62 can be ignored by an order of magnitude faster than the propagation time of the elastic wave, the waveform acquisition device 22 includes the elastic wave oscillation device 11. The oscillation time can be recorded at substantially the same timing as the timing of oscillating the elastic wave. Thereafter, as described above, the waveform acquisition device 22 records the vibration waveform transmitted from each elastic wave receiving device 21 and the time information of the internal clock together.

  Thus, by recording the oscillation time of the elastic wave with the waveform acquisition device 22, the time axis of the oscillation time and the vibration receiving time can be matched, so that the recording information of the oscillation-side equipment 10 is not interposed. The propagation time of the elastic wave from the elastic wave oscillating device 11 to each elastic wave receiving device 21 can be calculated with high accuracy.

  The waveform acquisition device 22 stops recording the waveform until the trigger signal is transferred from the underground radio reception device 62, and at the timing when the start signal transmitted from the underground radio reception device 62 is received, Recording of the waveform transmitted from the elastic wave receiving device 21 may be started. As a result, the waveform acquisition device 22 can obtain the receiving time of the elastic wave received by each elastic wave receiving device 21 with reference to the time when the waveform is recorded. It is possible to determine the propagation time of the elastic wave from when the wave is oscillated until each elastic wave receiving device 21 receives the vibration.

[Fifth Embodiment]
Next, a geological exploration system according to the fifth embodiment will be described. FIG. 8 is a longitudinal sectional view showing a geological exploration system according to the fifth embodiment. As shown in FIG. 8, the geological exploration system 5 according to the fifth embodiment is basically the same as the geological exploration system 4 according to the fourth embodiment, and triggers from the oscillation side equipment 10 to the vibration receiving side equipment 20. Only the method of transmitting a signal is different. For this reason, in the following description, only the part which is different from the fourth embodiment will be described, and the description of the part similar to the fourth embodiment will be omitted.

  The geological exploration system 5 is a radio master unit 71 and a radio slave unit 72 that perform normal radio communication instead of the underground radio transmission device 61 and the underground radio reception device 62 of the geological exploration system 4 according to the fourth embodiment. Furthermore, a plurality of relay devices 73 (73a to 73e) are installed on a route from the wireless master device 71 through the tunnel A to the wireless slave device 72. In addition, since all the relay machines 73a-73e are the same structures, below, it demonstrates as the relay machine 73 except the case where it designates especially.

  The oscillation time detection device 12 wirelessly transmits a trigger signal from the wireless master device 71 when the initial motion of the elastic wave is detected by an initial motion detection sensor or the like. Then, each relay station 73 sequentially transfers this trigger signal to the wireless slave unit 72, and the wireless slave unit 72 receives the transmitted trigger signal and transmits it to the waveform acquisition device 22.

  The waveform acquisition device 22 that has received the trigger signal transmitted from the wireless slave device 72 records the time of the internal clock when the trigger signal is received as the oscillation time at which the elastic wave was oscillated from the elastic wave oscillation device 11. . That is, since the wireless communication between the wireless master device 71 and the wireless slave device 72 via the relay device 73 can be ignored by orders of magnitude faster than the propagation time of the elastic wave, the waveform acquisition device 22 can generate the elastic wave oscillation. The oscillation time can be recorded at substantially the same timing as when the device 11 oscillates the elastic wave. Thereafter, as described above, the waveform acquisition device 22 records the vibration waveform transmitted from each elastic wave receiving device 21 and the time information of the internal clock together.

  In this way, even when the trigger signal is transmitted from the oscillation time detection device 12 of the oscillation side equipment 10 to the waveform acquisition device 22 of the vibration reception side equipment 20 by wireless communication via the relay 73, it is the same as in the fourth embodiment. There is an effect.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, in the first embodiment, it has been described that the receiving time of the elastic wave received by each elastic wave receiving device 21 is detected by the analysis computer 30 based on each waveform and time information recorded by the waveform acquiring device 22. However, it is good also as what the waveform acquisition apparatus 22 detects.

  Each embodiment can be appropriately combined. For example, the arrangement in which the elastic wave oscillation device and the elastic wave receiving device described in the second embodiment are replaced may be applied to other embodiments. Further, the technique for performing tomographic analysis including the past accumulated information described in the third embodiment may be applied to other embodiments.

  Next, examples of the present invention will be described.

  First, as a comparative example to the embodiment, in order to perform two-dimensional tomography analysis, a two-dimensional model in which a fault fracture zone B exists in front of the face of tunnel A is created, and eleven elastic wave oscillators are formed in tunnel A. 11 were arranged in a straight line, and 15 elastic wave receiving devices 21 were arranged in a straight line on the ground surface in front of the face. In this two-dimensional model, the elastic wave propagation velocity Vp in the fault crush zone B is 3 km / s, and the elastic wave propagation velocity Vp in other positions is 4 km / s. Then, the propagation velocity of the elastic wave from each elastic wave oscillator 11 to each elastic wave receiver 21 was simulated, and the elastic wave velocity distribution ahead of the face was generated by two-dimensional tomography analysis. FIG. 9 shows an elastic wave velocity distribution as a simulation result of the comparative example, and an elastic crush band obtained from this elastic wave velocity distribution is indicated by B ′.

  On the other hand, as an example, in order to perform three-dimensional tomography analysis, a three-dimensional model in which a fault crushing zone B exists in front of the face of tunnel A is created, and sixty elastic wave oscillators 11 are arranged in the tunnel A well. Originally arranged, 36 elastic wave receiving devices 21 were two-dimensionally arranged on the ground surface in front of the face. In this three-dimensional model, the elastic wave propagation velocity Vp in the fault crush zone B is 3 km / s, and the elastic wave propagation velocity Vp in other positions is 4 km / s. Then, the propagation velocity of the elastic wave from each elastic wave oscillator 11 to each elastic wave receiver 21 was simulated, and an elastic wave velocity distribution in front of the face was generated by three-dimensional tomography analysis. FIG. 10 shows an elastic wave velocity distribution, which is a simulation result of the example, and an elastic crush band obtained from the elastic wave velocity distribution is indicated by B ′.

  As shown in FIG. 9, in the comparative example, the position of the fault crush zone B 'and the degree of hardness can be grasped to some extent, but it is difficult to say that it is clear. In addition, since the formation at a position outside the analysis target cross section is unknown, it is difficult to determine whether or not a fault crush zone exists at the position of the fault crush zone B 'grasped from the elastic wave velocity distribution.

  On the other hand, as shown in FIG. 10, in the embodiment, since the elastic wave velocity distribution is displayed three-dimensionally, it is possible to clearly grasp the position of the analyzed fault crush zone B ′ and the degree of hardness. Is possible. Moreover, since the fault fracture zone B ′ is shown as a wide area, it is easy to determine whether or not the fault fracture zone exists at the position of the fault fracture zone B ′ that is grasped from the elastic wave velocity distribution. Can do.

  DESCRIPTION OF SYMBOLS 1-6 ... Geological exploration system, 10 ... Oscillation side equipment, 11 (11a-11c) ... Elastic wave oscillation device, 12 ... Oscillation time detection device, 13 ... Time information receiving device, 14 ... Optical transmission line, 14a ... Optical fiber Cable, 14b ... Optical transmitter, 14c ... Optical receiver, 15 ... Clocking device, 20 ... Vibration receiving side equipment, 21 (21a-21f) ... Elastic wave receiving device, 22 ... Waveform acquisition device (vibration time detecting means), DESCRIPTION OF SYMBOLS 23 ... Time information receiver, 24 ... Clock device, 26 ... Underground radio receiver, 30 ... Analysis computer (vibration time detection means, analysis means), 40 ... Oscillation side equipment, 41 (41a-41f) ... Elastic wave Oscillating device, 42 ... oscillation time detecting device, 43 ... time information receiving device, 44 ... clocking device, 50 ... receiving device, 51 ... elastic wave receiving device, 52 ... waveform acquisition device (vibration time detecting means), 53 ... Time information receiver 54 ... Optical transmission line, 54a ... Optical fiber cable, 54b ... Optical transmitter, 54c ... Optical receiver, 55 ... Clocking device, 61 ... Underground wireless transmitter, 62 ... Underground wireless receiver, 71 ... Wireless Master unit, 72: wireless slave unit, 73 (73a to 73e) ... relay unit, A ... tunnel, B ... fracture zone.

Claims (3)

A geological exploration system for exploring the geology ahead of the face of a tunnel excavating based on the propagation time of elastic waves,
Elastic wave oscillation means for oscillating an elastic wave;
Oscillation time detecting means for detecting an oscillation time at which an elastic wave is oscillated from the elastic wave oscillating means;
Elastic wave receiving means for receiving elastic waves;
A receiving time detecting means for detecting a receiving time when the elastic wave receiving means receives the elastic wave;
From the propagation time of the elastic wave from the elastic wave oscillation means to the elastic wave reception means calculated based on the oscillation time detected by the oscillation time detection means and the vibration reception time detected by the vibration reception time detection means, the tomography An analysis means for generating an elastic wave velocity distribution in front of the face of the tunnel using analysis;
Synchronization means for matching the oscillation time detected by the oscillation time detection means and the vibration reception time detected by the vibration reception time detection means on the same time axis;
Have
In the tunnel mine, either one of the elastic wave oscillation means or the elastic wave receiving means is disposed,
On the ground surface in front of the face, either one of the elastic wave oscillating means or the elastic wave receiving means is two-dimensionally or three-dimensionally arranged,
The oscillation time detection means and the vibration reception time detection means are arranged on either the tunnel pit or the ground surface in front of the face where the elastic wave vibration reception means is arranged, and have the same time information.
When the elastic wave is oscillated from the elastic wave oscillating means, the synchronizing means is triggered by a radio transmission means arranged either in the tunnel pit where the elastic wave oscillating means is arranged or on the ground surface in front of the face. Wirelessly transmitted to the oscillation time detection means and the vibration receiving time acquisition means,
The geological exploration system, wherein the oscillation time detection means sets the reception timing of the trigger signal as an oscillation time when an elastic wave is oscillated from the elastic wave oscillation means. 2. The geological exploration system according to claim 1 , wherein when receiving the trigger signal, the receiving time detection unit starts detecting a receiving time at which the elastic wave receiving unit receives an elastic wave. The geological exploration system according to claim 1 or 2 , wherein a plurality of either the elastic wave oscillating means or the elastic wave receiving means are arranged in a tunnel mine.

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