JP6258010B2 - Elastic wave velocity measuring method and elastic wave velocity measuring system - Google Patents

Description

  The present invention relates to an elastic wave velocity measuring method and an elastic wave velocity measuring system for measuring an elastic wave velocity in the ground.

  Conventionally, when constructing structures such as tunnels and dams, the underground geology is investigated by measuring the elastic wave velocity in the ground of the construction site. This measurement of elastic wave velocity is performed before construction of the structure and the measurement results are reflected in the design strength, etc., and are also performed sequentially during the construction of the structure, and the design data is reviewed using the measurement results. Etc. are performed.

  As a method for measuring the elastic wave velocity, for example, as shown in FIG. 7, blasting with an explosive such as dynamite is performed at an oscillation point 700, and the times at which vibrations due to blasting arrive at a plurality of measurement points 702A to 702J are measured. A method of estimating the elastic wave velocity between the blasting point 700 and the measurement points 702A to 702J is generally performed (for example, see Patent Document 1 below).

  Further, as a more simple method of measuring the elastic wave velocity, for example, as shown in FIG. 8B, vibration is generated by hitting the ground surface G with a hammer 800 and is installed at a predetermined distance from the vibration occurrence location. There is known a method of estimating an elastic wave velocity between a vibration generation point and a measurement point by measuring the arrival time of vibration with the measuring device 802. In this method, as shown in FIG. 8A, the distance L from the vibration measuring device 802 is changed to generate vibrations at a plurality of locations, and a travel time curve composed of the vibration arrival time T (ΔT) and the distance L (ΔL) is obtained. The elastic wave velocity V is obtained by creating the elastic wave velocity.

JP 07-259472 A

  In the method using explosive blasting and the method using a hammer as described above, in order to prevent confusion between vibration caused by blasting for elastic wave velocity measurement and other vibrations, construction work should be performed when making measurements during construction of the structure. There is a problem that it needs to be interrupted. Moreover, in the method using blasting with the above-mentioned explosive, it is necessary to install a plurality of vibration measuring devices, and there is a problem that the measurement is complicated. Further, in the method using the hammer described above, since vibration is generated by human power, the measurement range is at most about 40 to 50 m, and there is a problem that measurement in a wide range cannot be performed.

  The present invention has been made in view of the above-described problems of the prior art, and provides an elastic wave velocity measuring method and an elastic wave velocity measuring system capable of measuring an elastic wave velocity in the ground by a simple method. For the purpose.

In order to solve the above-described problems and achieve the object, an elastic wave velocity measuring method according to the present invention is an elastic wave velocity measuring method for measuring an elastic wave velocity in the ground, and includes noise and vibration at an arbitrary oscillation point. At the same time, a measurement step of measuring the arrival time of the noise and the arrival time of the vibration generated in the oscillation step at a measurement point that is a predetermined distance away from the oscillation point, and the measurement step Based on the measured arrival time of the noise and the predetermined distance, a generation time estimation step for estimating the generation time of the noise and the vibration, and the generation of the noise and the vibration estimated in the generation time estimation step time on the basis on the arrival time of the vibration, and a seismic velocity calculating step of calculating the elastic wave velocity in the ground between the measuring point and the oscillation point, the generation time estimation The sound velocity value is corrected based on the temperature near the measurement point or the oscillation point, and the time required to reach the noise is calculated by dividing the predetermined distance by the sound velocity value. The generation time of the noise and the vibration is estimated by subtracting the time required for the arrival of the noise from the arrival time, and in the elastic wave velocity calculation step, the vibration is calculated from the generation time of the noise and the vibration and the arrival time of the vibration. And the elastic wave velocity is calculated by dividing the predetermined distance by the arrival time of the vibration .
An elastic wave velocity measurement system according to the present invention is an elastic wave velocity measurement system for measuring an elastic wave velocity in the ground, and an oscillation device that simultaneously generates noise and vibration at an arbitrary oscillation point, and the oscillation A noise measurement device that measures the arrival time of the noise generated by the device at a measurement point that is a predetermined distance away from the oscillation point, and a vibration measurement that measures the arrival time of the vibration generated by the oscillation device at the measurement point Based on the apparatus, the arrival time of the noise and the predetermined distance, the generation time of the noise and the vibration is estimated, and based on the estimated generation time of the noise and the vibration and the arrival time of the vibration, and an elastic wave velocity calculating unit for calculating a seismic velocity in the ground between the measuring point and the oscillation point, Oyo the noise caused by the acoustic wave velocity calculating device The generation time of the vibration is corrected by correcting the sound speed value based on the temperature in the vicinity of the measurement point or in the vicinity of the oscillation point, and dividing the predetermined distance by the sound speed value to obtain the time required to reach the noise. Is calculated by subtracting the time required to reach the noise from the arrival time of the noise,
The elastic wave velocity is calculated by the elastic wave velocity calculating device by calculating the time required to reach the vibration from the generation time of the noise and vibration and the arrival time of the vibration, and determining the arrival time of the vibration by the predetermined distance. It is made by dividing by time .

  According to the present invention, noise and vibration are simultaneously generated at the oscillation point, the arrival time of the noise and the arrival time of the vibration at the measurement point are respectively measured, and between the oscillation point and the measurement point based on the measurement result Calculate the elastic wave velocity in the ground. Thereby, the vibration used for the measurement can be distinguished from other vibrations, and the elastic wave velocity can be measured without interrupting the construction work even during the construction of the structure.

It is explanatory drawing which shows the structure of the elastic wave velocity measurement system 10 concerning embodiment. 3 is a graph showing an example of a waveform measured by a noise measurement device 104. 3 is a graph showing an example of a waveform measured by a vibration measuring device 106. It is explanatory drawing explaining the elastic wave velocity calculation method by the elastic wave velocity calculation apparatus. 3 is a flowchart showing a procedure of an elastic wave velocity measuring method by the elastic wave velocity measuring system 10. FIG. 5 is an explanatory diagram showing elastic wave velocity distribution at the time of designing a tunnel T. It is explanatory drawing which shows the elastic wave velocity measuring method concerning a prior art. It is explanatory drawing which shows the elastic wave velocity measuring method concerning a prior art.

  Exemplary embodiments of an elastic wave velocity measuring method and an elastic wave velocity measuring system according to the present invention will be described below in detail with reference to the accompanying drawings. In the present embodiment, measurement of elastic wave velocity at a tunnel excavation site will be described as an example.

(Embodiment)
FIG. 1 is an explanatory diagram illustrating a configuration of an elastic wave velocity measurement system 10 according to an embodiment. As described above, in this embodiment, the elastic wave velocity in the ground around the tunnel T being excavated is measured. The tunnel T shown in FIG. 1 is excavated from the wellhead E, and a tunnel is formed up to the face P. The face P is provided with an oscillation device 102 that simultaneously generates noise and vibration. In the present embodiment, the oscillation device 102 is a device that blasts with explosives in excavation of the tunnel T such as dynamite, and generates noise and vibration by blasting. Hereinafter, a point where the oscillation device 102 is installed is referred to as an “oscillation point”.

  Also, at the wellhead E, a noise measuring device 104 that measures the arrival time of the noise generated by the oscillator 102 at a measurement point (wellhead E) that is a predetermined distance (distance L in FIG. 1) from the oscillation point, and the oscillator A vibration measuring device 106 is provided that measures the arrival time of vibration generated by 102 at a measurement point. The noise measurement device 104 and the vibration measurement device 106 are installed at substantially the same position, and the point is set as a measurement point. The distance L between the measurement point and the oscillation point is accurately measured in advance. Further, the noise measurement device 104 and the vibration measurement device 106 may be housed in the same housing, or a single measurement device having the functions of both devices may be installed at the measurement point.

  The noise measuring device 104 and the vibration measuring device 106 can employ various types of conventionally known ones, but for the convenience of measurement, a small, light and dry cell drive type is preferable. The data measurement by the noise measurement device 104 and the vibration measurement device 106 is preferably performed at a high frequency in order to increase measurement accuracy.

  FIG. 2 is a graph showing an example of a waveform measured by the noise measurement device 104. FIG. 3 is a graph showing an example of a waveform measured by the vibration measuring device 106. 2 and 3, the vertical axis represents noise or vibration intensity, and the horizontal axis represents time. 2 and 3, the measurement is performed at the same time, and the distance between the oscillation point and the measurement point (predetermined distance L) is 300 m. In the graph of FIG. 3, the vibration (waveform 31) due to the blasting without reaching the time point reaches the measurement point at time T1. Thereafter, the vibration due to the second stage blasting (waveform 32) at time T2, the vibration due to the third stage blasting (waveform 33) at time T3, and the vibration due to the fourth stage blasting (waveform 34) at time T4, respectively. The point has been reached. In addition, after the vibration (waveform 34) due to the fourth blast, the blast vibration is unknown due to the influence of low frequency noise. Note that blasting is not necessarily performed a plurality of times, and may be performed at least once.

  Moreover, in the graph of FIG. 2, the noise by the blast of the heart reaches the measurement point at time T5. Time T5 is substantially the same as time T4 in FIG. 3 (vibration arrival time due to the fourth blast), and it can be seen that the time required for the noise to reach is longer than vibration. In the graph of FIG. 2, noise due to blasting after the second stage cannot be clearly identified.

  Returning to the description of FIG. 1, the noise measuring device 104 and the vibration measuring device 106 are connected to an elastic wave velocity calculating device 108. The elastic wave velocity calculation device 108 estimates the generation time of noise and vibration based on the arrival time of noise and the distance between the oscillation point and the measurement point (predetermined distance L), and the estimated generation time of the noise and vibration Based on the arrival time of vibration, the elastic wave velocity in the ground between the oscillation point and the measurement point is calculated. The elastic wave velocity calculation device 108 includes a CPU, a ROM that stores and stores a calculation program, a RAM as an operation area of the calculation program, an EEPROM that holds various data in a rewritable manner, an interface unit that interfaces with peripheral devices, An output unit for outputting a calculation result is included.

  FIG. 4 is an explanatory diagram for explaining an elastic wave velocity calculation method by the elastic wave velocity calculator 108. The graph of FIG. 4 is a superposition of the graphs of FIG. 2 and FIG. The elastic wave velocity calculation device 108 first estimates the generation time of noise and vibration based on the arrival time of noise and the predetermined distance L. At this time, the elastic wave velocity calculation device 108 divides the predetermined distance L by the sound velocity value to calculate the required time for noise arrival. Then, the noise occurrence time is estimated by subtracting the noise arrival time from the noise arrival time.

  Specifically, using FIG. 4, the predetermined distance L in FIG. 4 is 300 m as in FIGS. 2 and 3, and when the sound velocity value is 340 m / sec, the required time Tα of noise at the predetermined distance L is 300/340 = 0.882 (sec). The noise and vibration occurrence time Tβ can be estimated by subtracting the noise required time Tα from the time T5 when the noise reaches the measurement point. Since the sound speed value changes depending on the temperature, if the sound speed value is corrected and the generation time of noise and vibration is estimated based on the temperature near the measurement point or the oscillation point, the acoustic wave velocity The calculation accuracy can be further improved.

  Subsequently, the elastic wave velocity calculation device 108 estimates the elastic wave velocity in the ground between the oscillation point and the measurement point based on the generation time of the noise and vibration and the arrival time of the vibration. More specifically, the elastic wave velocity calculation device 108 calculates the required time for vibration from the generation time of noise and vibration and the arrival time of vibration, and divides the predetermined distance L by the required time for arrival of vibration to generate the elastic wave. Estimate speed.

  More specifically, the elastic wave velocity calculation device 108 uses the difference between the noise and vibration generation time Tβ and the vibration arrival time T1 due to the blasting of the center as the vibration required time Tγ. In the example of FIG. 4, the required time Tγ of vibration is about 0.0988 sec. Then, the elastic wave velocity in the ground is calculated by dividing the predetermined distance L by the required arrival time Tγ of vibration. In the example of FIG. 4, the elastic wave velocity is 300 / 0.0988 = 3040 m / sec (approximately 3.0 km / sec).

  FIG. 6 is an explanatory diagram showing the elastic wave velocity distribution when the tunnel T is designed. In FIG. 6, the elastic wave velocity between the oscillation point 600 and the measurement point 602 is estimated to be 3.6 to 4.4 km / sec (see the underlined portion). On the other hand, the elastic wave velocity measured by the elastic wave velocity measuring system 10 is 3.0 km / sec, and the actual elastic wave velocity is slower than the design prediction. That is, the ground around the measurement area may be softer than predicted, and the support pattern at the time of design may need to be reviewed.

  FIG. 5 is a flowchart showing the procedure of the elastic wave velocity measuring method by the elastic wave velocity measuring system 10. In the flowchart of FIG. 5, the measurer first installs the oscillation device 102 at the blasting point, and the noise measurement device 104 and the vibration measurement device 106 at the measurement point (step S501). At this time, the distance (predetermined distance L) between the blasting point and the measuring point is accurately measured.

  Next, blasting is performed by the oscillation device 102, and noise and vibration are generated simultaneously (step S502). Simultaneously with step S502, noise and vibration generated by blasting are measured by the noise measuring device 104 and the vibration measuring device 106 (step S503). When the measurement is completed, the elastic wave velocity calculation device 108 estimates the blast time (noise and vibration occurrence time) from the distance between the blast point and the measurement point and the arrival time of the noise (step S504). Then, the arrival time of vibration is estimated from the blast time and the arrival time of vibration, and the elastic wave velocity is further calculated (step S505). The elastic wave velocity calculation device 108 outputs the calculated elastic wave velocity by display or the like (step S506), and ends the processing according to this flowchart.

  As described above, the elastic wave velocity measuring system 10 according to the embodiment generates noise and vibration at the oscillation point at the same time, measures the arrival time of the noise and the arrival time of the vibration at the measurement point, and measures them. Based on the result, the elastic wave velocity in the ground between the oscillation point and the measurement point is calculated. Thereby, the vibration used for the measurement of elastic wave velocity can be distinguished from other vibrations, and the elastic wave velocity can be measured even during construction of the structure without interrupting the construction work.

  Further, the elastic wave velocity measuring system 10 estimates the generation time of noise and vibration from the predetermined distance L, the sound velocity value, and the arrival time of the noise, so it is not necessary to record the generation time of the vibration strictly. Vibrations in construction work can be used for measurement. In addition, when calculating using the sound velocity value, if the sound velocity value is corrected based on the temperature near the measurement point or the oscillation point, the measurement accuracy of the elastic wave velocity can be further improved. it can.

  In addition, since the elastic wave velocity measurement system 10 uses an arbitrary point in the tunnel T during excavation as an oscillation point and a measurement point, the surrounding geology is consistent with the prediction at the time of design while the excavation work of the tunnel T is advanced. Can be confirmed. In the elastic wave velocity measurement system 10, if the oscillation point is the face of the tunnel T, the elastic wave velocity can be measured using blasting for advancing tunnel excavation. There is no need to perform blasting, and cost and human costs can be reduced.

  In FIG. 1, the oscillation device 102 is provided at the face P, and the noise measurement device 104 and the vibration measurement device 106 are provided at the wellhead E. However, the installation location (oscillation point) of the oscillation device 102, the noise measurement device 104, and the vibration measurement The installation location (measurement point) of the device 106 can be an arbitrary location around the tunnel T. Further, a soundproof door or the like may be provided at the wellhead E so that noise generated by blasting does not leak to the surroundings.

  Further, in the present embodiment, the case where the elastic wave velocity around the tunnel being excavated is described, but the present invention is not limited to this, and the present invention is applied to the measurement of elastic wave velocity at the design investigation stage of the tunnel to be constructed. May be. Further, the present invention may be applied not only to tunnels but also to construction of other structures such as dams.

  In this embodiment, an oscillation device using explosives is used as an example of the oscillation device 102. However, the present invention is not limited to this, and noise and vibration are simultaneously generated by other construction equipment used for tunnel excavation such as a compactor. May be. In this embodiment, one noise measurement device 104 and one vibration measurement device 106 are installed. However, the present invention is not limited to this, and a plurality of noise measurement devices 104 and vibration measurement devices 106 are prepared. Measurements may be made at multiple locations.

  DESCRIPTION OF SYMBOLS 10 ... Elastic wave velocity measuring system, 102 ... Oscillator, 104 ... Noise measuring device, 106 ... Vibration measuring device, 108 ... Elastic wave velocity calculating device

Claims (6)

An elastic wave velocity measuring method for measuring an elastic wave velocity in the ground,
An oscillation process for simultaneously generating noise and vibration at an arbitrary oscillation point;
A measurement step of measuring the arrival time of the noise generated in the oscillation step and the arrival time of the vibration at a measurement point that is a predetermined distance away from the oscillation point;
A generation time estimation step of estimating the generation time of the noise and the vibration based on the arrival time of the noise measured in the measurement step and the predetermined distance;
An elastic wave that calculates an elastic wave velocity in the ground between the oscillation point and the measurement point based on the noise and the vibration generation time and the vibration arrival time estimated in the generation time estimation step. Including a speed calculation step ,
In the generation time estimation step, the sound speed value is corrected based on the temperature in the vicinity of the measurement point or the oscillation point, and the time required for reaching the noise is calculated by dividing the predetermined distance by the sound speed value. , Subtracting the time required to reach the noise from the arrival time of the noise to estimate the generation time of the noise and the vibration,
In the elastic wave velocity calculating step, the time required to reach the vibration is calculated from the generation time of the noise and the vibration and the arrival time of the vibration, and the predetermined distance is divided by the required time to reach the vibration. Calculate wave velocity,
The elastic wave velocity measuring method characterized by the above-mentioned. The oscillation point and the measurement point are arbitrary points in the tunnel being excavated,
The elastic wave velocity measuring method according to claim 1 . The oscillation point is the face of the tunnel, and the measurement point is a tunnel entrance or an arbitrary location within the tunnel anti-node,
The elastic wave velocity measuring method according to claim 2 . In the oscillation step, the noise and the vibration are generated by blasting with explosives in excavation of the tunnel.
Elastic wave velocity measurement method according to claim 2 or 3, characterized in that. An elastic wave velocity measurement system for measuring elastic wave velocity in the ground,
An oscillation device that simultaneously generates noise and vibration at an arbitrary oscillation point;
A noise measurement device that measures the arrival time of the noise generated by the oscillation device at a measurement point that is a predetermined distance away from the oscillation point;
A vibration measurement device for measuring the arrival time of the vibration generated by the oscillation device at the measurement point;
Based on the arrival time of the noise and the predetermined distance, the generation time of the noise and the vibration is estimated, and based on the estimated generation time of the noise and the vibration and the arrival time of the vibration, the oscillation point And an elastic wave velocity calculating device for calculating an elastic wave velocity in the ground between the measurement point and the measurement point ,
The estimation of the generation time of the noise and the vibration by the elastic wave velocity calculation device corrects the sound speed value based on the temperature in the vicinity of the measurement point or in the vicinity of the oscillation point, and sets the predetermined distance to the sound speed value. Divided by calculating the required time for reaching the noise, and subtracting the required time for reaching the noise from the time the noise reaches,
The elastic wave velocity is calculated by the elastic wave velocity calculating device by calculating the time required to reach the vibration from the generation time of the noise and vibration and the arrival time of the vibration, and determining the arrival time of the vibration by the predetermined distance. Made by dividing by time,
An elastic wave velocity measuring system characterized by that.   The oscillation point and the measurement point are arbitrary points in the tunnel being excavated,
  The oscillation device generates the noise and the vibration by blasting with explosive in excavation of the tunnel,
  The elastic wave velocity measuring system according to claim 5.

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