JPH10307128A - Method for predicting slope disaster by acoustic emission technology - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve precision in a slope disaster predicting method, for actualization, which uses an acoustic emission technology. SOLUTION: Along with an acoustic emission technology wherein parameters are the number and magnitude of AE(acoustic emission) which takes place following a breakdown of a slope 1, the same sound as generated periodically at an artificial sound source 5 set at an AE sensor 3 and its opposite side across a collapse part of the slope 1 is measured with the AE sensor 3 and such parameter of an observed value as the level of its decay is also/additionally used. Thus, a prediction precision is improved by utilizing such nature as a sound decays as a breakdown proceeds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a slope disaster prediction method using an emission method.

[0002]

2. Description of the Related Art Conventionally, slope disaster prediction is performed by a method of restricting traffic on a road by rainfall or by predicting the occurrence of a disaster by visually observing a small rock falling from a slope to a road. It is a method of the degree. Prediction by these methods mostly depends on the experience of the predictor, and there are many problems as a prediction method.

[0003] The collapse of the Toyohama tunnel in Kodaira, Hokkaido in February 1996 reaffirmed the need for advanced methods for predicting landslides and preserving human lives. It is a situation that is being carried out in various fields. At the research level, we take advantage of the fact that slopes have undergone small-scale destruction before large-scale collapses have taken place, and we have developed acoustic emissions (sounds associated with slope failures: (Hereinafter referred to as AE) has been studied in many ways for predicting large-scale collapse in advance.

[0004] In other words, the method of predicting slope disasters by the AE method that has been carried out at the conventional research level is based on a change in the frequency of occurrence of AEs (the more AEs near the collapse of a large slope, the more AEs)
Is predicted) by observing a change in AE amplitude (a large AE occurs as a large-scale slope collapse approaches). In addition, Japanese Patent Application Laid-Open No.
In the proposal disclosed in Japanese Patent Publication No. 01, AE (Acoustic Emission), in which sound energy is released due to cracks and deformation occurring inside the ground, is supplemented by an AE sensor buried underground. Converted to electrical signal
Inputs and analyzes the count data of the AE electric signal connected to the E sensor to the computer, analyzes the number of AE signals received by the AE sensor, and changes in the amplitude distribution and other physical phenomena that occur inside the ground. In the method of monitoring the safety of the conventional ground where the evaluation has been performed, and expressing only the number of the collapse locations of the ground on the one-dimensional coordinates on the waveguide and evaluating the AE signal, Since it is assumed that the collapse position is evaluated only by the number, the position is located for all the waves propagating through the waveguide, so when the collapse position is located in one-dimensional coordinates, a clear position It is stated that a more accurate method for locating a slope failure position by AE energy is provided. The content of the method is to evaluate the accumulation of AE energy in the evaluation method of the collapse position where the AE sound generated due to the internal destruction behavior of the ground is converted into an electric signal and evaluated and analyzed. According to the conventional method using numbers, both the large AE wave and the small AE wave are only one wave, but in the present proposal, the size of the AE wave is represented on one-dimensional coordinates because the evaluation is based on the accumulation of AE energy. The conventional method based on the counting of AE signals makes it possible to clearly identify the ground collapse position.

[0005]

However, in reality, a technique of measuring the sound of destruction of rock or ground by using an acoustic emission technique to predict a disaster on a slope has not been put to practical use. This is because the AE measurement always includes noise, so whether the obtained AE data is a significant sound generated due to the destruction of the slope, or a noise generated from rainfall or vehicles traveling on the road, etc. The main reason is that the technology is difficult. That is, in order to remove noise, measures such as lowering the sensitivity of the measurement sensor are taken. However, a significant AE itself generated due to the destruction of the slope is a very small signal. The AE itself cannot be measured. Therefore, it is necessary to extract only a significant signal from data containing noise obtained by a high-sensitivity measurement sensor, but this is difficult, and this is a major obstacle to practical use.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the slope disaster prediction accuracy of an acoustic emission method and to make it practical.

[0007]

In order to achieve the above object, a slope disaster prediction method using an acoustic emission method according to the present invention has two parameters, the number and the size of AEs generated due to the destruction of the slope. AE with acoustic emission method with slope collapse
The same sound periodically generated from an artificial sound source installed on the opposite side of the sensor is measured by the AE sensor, and the parameter of the observed value of the degree of attenuation is additionally used. The prediction accuracy is improved by utilizing the property of being easily attenuated.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. As shown in the figure, the AE sensor 3 is installed near the predicted position 2 of the slip failure of the disaster prediction target slope 1 with the waveguide 4 buried underground to measure AE. The parameters at the time of measurement are two, that is, the number and magnitude of AEs generated when the slope 1 is broken. On the other hand, an artificial sound source 5 is installed on the opposite side of the AE sensor 3 across the collapse portion of the slope 1 (the collapse position of the slope (the predicted position 2 in the figure)
It is quite possible to make a rough estimate of). The same sound (frequency, amplitude, etc.) is periodically generated from this sound source 5, and this sound is measured by the AE sensor 3 installed on the opposite side across the collapsed portion. Since cracks and the like are generated as the destruction progresses at the collapsed portion, even if the same sound is generated from the sound source 5, the sound measured by the AE sensor 3 changes to a small sound. In other words, it is possible to predict the degree of the destruction by utilizing the property that the sound is easily attenuated as the destruction progresses. Thus, in addition to the number and magnitude of AEs caused by the destruction of the slope, the degree of attenuation of the artificially generated sound is observed, and by using this, the accuracy of slope disaster prediction is improved.

There are many possible artificial sound sources, such as a method of generating electricity electrically by a speaker and a method of mechanically hitting the ground. If the sound is generated for a period of, for example, about one minute in a day and the method is continued for a long period of time, normal AE measurement can be performed for most of the day. It is.

[0010]

As described above, the present invention has the following advantages. The method according to the present invention in which an artificial sound is generated in addition and combined and the sound is observed is advantageous in that the nature (loudness, etc.) of the sound of the generating source is known, so that separation from noise is easy. Having. For example, when a sound louder than an artificially generated sound is observed, it is clear that the signal is noise, and the noise can be easily separated. Also, while the conventional method of predicting slope disasters by AE at the research level is a so-called passive measurement that targets only sound generated due to the collapse of a slope, the present invention artificially measures This is an active measurement such as generating a sound and measuring it. Therefore, in the case where only a minute AE that cannot be caught by the sensor is generated, but the slope is being broken, the conventional method does not generate the AE and the slope is sound. While it is conceivable to evaluate that, in the present invention, to observe the attenuation of the artificially generated sound, the change in the attenuation of the sound is captured and the evaluation that the destruction is in progress is evaluated This greatly increases the accuracy of slope disaster prediction.

[Brief description of the drawings]

FIG. 1 shows a conceptual diagram of AE measurement according to the present invention.

[Explanation of symbols]

 1 Slope for disaster prediction 2 Predicted position 3 AE sensor 4 Waveguide 5 Sound source

Continuing from the front page (72) Inventor Muneaki Hatanaka 1-5-1, Otsuka, Inzai City, Chiba Prefecture Inside the Technical Research Institute of Takenaka Corporation (72) Inventor Takafumi Shimokawachi 1-5-1, Otsuka 1, Inzai City, Chiba Prefecture Co., Ltd. Inside Takenaka Corporation Technical Research Institute (72) Inventor Toshiaki Ishise 1-5-1, Otsuka, Inzai City, Chiba Prefecture Inside Takenaka Corporation Technical Research Institute (72) Inventor Go Nishinakagawa 1-5-1, Otsuka, Inzai City, Chiba Prefecture Takenaka Corporation Technical Research Institute, Inc. (72) Inventor Takao Ueda 8-2-1-1, Ginza, Chuo-ku, Tokyo Inside Takenaka Corporation, Tokyo Main Store (72) Inventor Takeshi Nagayama 8-chome, Ginza, Chuo-ku, Tokyo 21-1 Takenaka Civil Engineering Co., Ltd. (72) Inventor Takeshi Kunishima 8-21-1, Ginza, Chuo-ku, Tokyo Inside Takenaka Road Co., Ltd.

Claims (4)

[Claims] 1. An artificial emission method which is installed on the opposite side of an AE sensor across a slope collapse part in an acoustic emission method in which parameters are two of the number and magnitude of AEs generated due to slope failure. The same sound that is periodically generated from a sound source is measured by the AE sensor, and the parameter of the observed value of the degree of attenuation is additionally used. The prediction is made using the property that the sound is easily attenuated as the destruction progresses. A slope disaster prediction method using an acoustic emission method characterized by improving accuracy. 2. The slope disaster prediction method according to claim 1, wherein the artificial sound source is an electrically generated speaker sound. 3. The slope disaster prediction method according to claim 1, wherein the artificial sound source is a sound that strikes the ground mechanically. 4. The method according to claim 1, wherein the generation time of the artificial sound source is set to a short time within a day, and the normal A
4. The slope disaster prediction method according to claim 1, 2 or 3, wherein the method does not hinder E measurement.