JP2002168612A - Method for measuring displacement of bedrock - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method with which the displacement of bedrock can be measured with high accuracy as much as possible, even though the cast is relatively low. SOLUTION: This method uses an acceleration sensor or speed sensor, which measures the acceleration or speed of vibrations caused by the displacement of the bedrock. The acceleration or speed sensor is fixedly set up in a measuring hole bored into the bedrock. The displacement of the bedrock is obtained by receiving and measuring the vibrations, caused by the displacement of the bedrock by means of the sensor and respectively integrating measured acceleration values twice or speed values once with time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the amount of mechanical displacement of a rock mass caused by an artificial or spontaneous cause.

[0002]

2. Description of the Related Art In measuring the behavior of a rock mass, a high-precision strain gauge is usually used for measuring the dynamic displacement amount of a rock mass which is artificially or spontaneously generated due to blasting work, mine excavation, earthquake or landslide. Is arranged at a predetermined position in the rock, and the obtained data is analyzed to obtain a displacement amount. In addition, a plurality of measuring rods having different lengths are inserted into the boring holes, and the expansion and contraction of these rods are measured with a dial gauge or the like to measure the displacement amount of the rock between the rods. Further, Japanese Patent Application Laid-Open No. 2000-97736 discloses that a magnetic flux output from a transmitting unit buried in rock is received by a receiving unit arranged on the ground, and the obtained output voltage is detected. A method of measuring the amount of displacement by performing division processing is disclosed.

[0003]

However, the measuring method using a strain gauge not only increases the size of the entire system but also allows the strain gauge once fixed to be easily moved to another place and reused. Not expensive. Also,
In the case of measuring the amount of displacement using a measuring rod, since the measurement of expansion and contraction is performed at intervals such as once a day or once a week, the amount of displacement cannot be continuously grasped. Further, in the technique described in the above publication, since the magnetic flux output from the transmitting unit to the receiving unit is affected by noises such as the earth's magnetic field and the lines of magnetic force in the rock, it is difficult to perform an accurate measurement.

[0004] It is an object of the present invention to provide a measuring method which can measure the displacement of a rock mass with high accuracy and continuously while being relatively inexpensive.

[0005]

According to the present invention, there is provided a method for measuring the amount of displacement of a rock using an acceleration sensor or a speed sensor for measuring the acceleration or speed of vibration accompanying the rock displacement. That is, an acceleration sensor or a speed sensor is fixed and installed in the measurement hole excavated in the rock. Then, the vibration is received by an acceleration sensor or a speed sensor,
The displacement amount of the rock is obtained by time-integrating the measured acceleration value or the measured speed value twice in the case of acceleration and once in the case of speed.

It is desirable that the acceleration sensor or the speed sensor have as high a sensitivity as possible, but it is not particularly limited to a specific structure. For example, an elastic wave velocity sensor described in Japanese Patent Application Laid-Open No. 11-166857 for investigating a rock fault or the like may be used. The acceleration sensor or speed sensor simultaneously measures the acceleration or speed of vibration due to displacement from three directions of the X axis, Y axis and Z axis,
It is desirable to obtain the three-dimensional displacement amount of the rock by performing the integration processing. A plurality of sensors are installed at required intervals on the rock to be measured, for example, by changing the depth position.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the method of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual configuration diagram showing an example in which the method of the present invention is applied to measurement of rock displacement around a tunnel. In the figure, reference numeral 1 is a tunnel, 2 is a bedrock, and 3 is a measurement hole excavated in the bedrock. The acceleration sensor 4 (4a-
4d) is inserted and fixed. The acceleration sensor 4 receives the vibration generated by the displacement of the rock through the inner wall surface of the measurement hole, and continuously outputs the measured value to the outside. In the present embodiment, four acceleration sensors 4 are arranged in the length direction of the measurement holes 3 and individually output measured value signals.

The measured acceleration signal is supplied to the first integrating circuit 5
And time-integrated to obtain a speed signal. Then, the speed signal is further input to the second integration circuit 6 and time-integrated again. The signal processed by the second integration circuit 6 becomes a displacement signal 7.
Each output signal such as a measured acceleration signal is amplified by an amplifier circuit as necessary and input to a subsequent circuit. The processing for these integration and amplification for the measured acceleration signal is
It is performed continuously. In addition, a correction circuit may be provided for an output signal from the integration circuit.

An example of a measurement output signal of the acceleration sensor 4 is as follows.
As shown in FIG. The figure shows a measurement record of the acceleration sensor for 0.6 seconds. The measured acceleration of the vibration reaches a peak at about 0.13 seconds, and becomes substantially zero at about 0.27 seconds. FIG. 3 shows a relationship between time and speed of a speed signal obtained by integrating the measured acceleration signal of FIG. The speed is about 3.6 (kine) at the peak. FIG. 4 shows a displacement amount obtained by time-integrating the speed signal of FIG. 3 again. It can be seen that the displacement that started at 0.13 seconds ends at about 0.27 seconds, and the amount of displacement was about 0.18 cm.

FIG. 5 is a table showing a comparison between the measured value of the displacement of the rock when measured using a μ strain gauge type displacement meter and the displacement at the corresponding time obtained by the method of the above embodiment. is there. The circle displacement in the figure indicates the peak displacement exemplified in FIG.
Also, the square marks indicate the final displacement value at 0.6 seconds in the case of FIG. The results of the comparison over 10 times are almost perfectly consistent. Therefore, it can be understood that the displacement measurement by the method of the present invention can be performed with almost no error as compared with the measurement by the conventional displacement meter.

In the measurement hole, a speed sensor can be provided instead of an acceleration sensor. In this case, the output signal from the speed sensor is input to the second integration circuit as shown by the path 7 in FIG. 1, and only one time integration process is performed. The result is no different from using an acceleration sensor. The acceleration sensor does not detect the acceleration of the vibration from one direction but arranges it three-dimensionally, thereby enabling displacement measurement in the X-axis, Y-axis, and Z-axis directions. In this case, either the case where the detection unit of the sensor is three-dimensionally arranged or the case where the acceleration sensor is three-dimensionally arranged may be used.

[0012]

According to the present invention, the following effects can be obtained. The amount of displacement of the rock is calculated by integrating the value measured by the acceleration sensor or the speed sensor twice or once with time, so that the displacement can be measured with the highest possible accuracy while being relatively inexpensive. . In addition, unlike the case where the displacement meter is read at a spot with a time interval, the vibration wave is continuously measured, so that the displacement amount of the rock can be continuously measured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an application example of a method according to an embodiment of the present invention.

FIG. 2 is a waveform chart showing an example of a measured acceleration signal output from an acceleration sensor.

FIG. 3 is a waveform diagram showing a speed signal obtained by time-integrating the measured acceleration signal of FIG. 2;

FIG. 4 is a graph showing a rock displacement amount obtained by time-integrating the speed signal of FIG. 3 again.

FIG. 5 is a table showing a comparison between a displacement value obtained by the method of the present invention and a value measured by a displacement meter.

[Explanation of symbols]

 1 Tunnel. 2 Bedrock. 3 Measurement hole. 4 (4a to 4d) acceleration sensors. 5 First integration circuit. 6 Second integration circuit.

 ──────────────────────────────────────────────────続 き Continued on the front page (71) Applicant 500548079 Hope Construction Consultant Co., Ltd. 2-3-2 Kamisui, Kumamoto City, Kumamoto Prefecture (72) Inventor Atsuo Hirata 5-15-8 Izumi, Kumamoto City, Kumamoto Prefecture Within Technology Co., Ltd. (72) Inventor Masahiko Yamazoe 2-3-2 Kamisui, Kumamoto-shi, Kumamoto F-term in Licotec Co., Ltd. (Reference) 2D043 AA00 AB07 2F069 AA02 AA04 AA06 AA43 BB40 GG19 GG41 GG65 HH30 NN06 2F076 BB09 BD02 BD04 BD19 BE09

Claims (3)

[Claims] An acceleration sensor for measuring acceleration of vibration accompanying displacement of a rock is fixed in a measurement hole excavated in the rock, and acceleration values received and measured by the acceleration sensor are time-integrated twice. A method for measuring the amount of displacement of a rock mass, wherein the displacement amount of the rock mass is obtained by performing the method. 2. A speed sensor for measuring a speed of vibration accompanying displacement of a rock is fixed in a measurement hole excavated in the rock, and an acceleration value received and measured by the speed sensor is
A method for measuring the displacement of a rock mass, wherein the displacement amount of the rock mass is obtained by performing time integration once. 3. The acceleration sensor or the speed sensor according to claim 1,
The rock mass displacement amount measuring method according to claim 1 or 2, wherein an acceleration or a speed due to vibrations from three directions of the X axis, the Y axis and the Z axis is measured to obtain a three-dimensional displacement amount of the rock mass.