JPH05112923A - Evaluating method for natural ground with ae measurement - Google Patents

Abstract

PURPOSE:To enable the change of destructive behavior in the internal section of natural ground, to be estimated in real time by grouping the AE signals of generation factors different from each other, and by monitoring the change of the number of generations of the representative AE(acoustic emission) signals of respective groups. CONSTITUTION:AE signals grasped by AE sensors 3, 3 inserted in natural ground 1 are converted to electric signal, and the input to a signal processor 9 is provided. After that, the input to a personal computer 10 is provided, and the waveforms of the AE signals are monitored by an oscilloscope 11. Then, the AE signals of generation factors different from each other are grouped, and from the change of the number of generations of the representative AE signals of respective groups, the change of momentarily changing destructive behavior in the internal section of the natural ground 1 is estimated in real time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used when the stability of natural ground is monitored by the AE method in construction work such as cut slopes artificially formed by cutting natural ground and underground rock caverns. It relates to a method for evaluating a natural ground by AE measurement.

[0002]

2. Description of the Related Art As a method of monitoring the safety of natural ground, AE (acoustic emission) in which sound energy is released due to cracks or deformations generated inside the natural ground
Is captured by an AE sensor embedded in the ground and converted into an electric signal, and the count data of the counting circuit of the AE electric signal connected to the AE sensor is input to the computer, analyzed, and received by the AE sensor. A method has been used to estimate the stability of the ground by estimating the physical phenomenon occurring inside the ground from the changes in the number of AE signals generated (the number of AE events) and the amplitude distribution.

[0003]

The AE method measures the amount of ground movement, and compares it with the method of monitoring the safety of the ground based on the state of change of the ground, so that the sign of rock mass collapse can be detected at an early stage. There is an advantage that it can be detected from. This is because AE occurs due to minute cracks and deformation inside the natural ground.

However, the conventional AE method does not employ an analysis method that reflects the characteristics of individual AE signals when evaluating measurement data. That is, even if signals having different characteristics were measured, they were all treated as similar signals. A microscopic view of the fracture behavior when a rock mass collapses shows that the internal fracture mechanism changes from moment to moment, and it has different characteristics according to this change.
E signal is generated.

Since the conventional analysis method does not consider such a signal characteristic, the physical meaning of the result obtained by the AE measurement becomes unclear, and the reliability of the ground stability monitoring method itself by the AE method is unclear. It also reduces sex. The present invention has been proposed in view of the above problems of the prior art, and the purpose thereof is to be able to distinguish the factors causing AE, and to analyze the fracture behavior inside the ground that changes momentarily. The point is to provide a method for evaluating natural grounds by AE measurement, which can be known to.

[0006]

In order to achieve the above object, according to the method for evaluating a natural ground by AE measurement according to the present invention, AE signals having different generation factors are grouped,
From the change in the number of representative AE signals generated in each group,
It is intended to estimate the destruction phenomenon inside the ground.

[0007]

According to the present invention, when the AE sound generated due to the internal destruction behavior of the natural ground is captured, converted into an electric signal and measured and analyzed, the AE signal calculated by the processing device of the signal is calculated. The AE signals are grouped according to a preset program from the characteristic parameters. Furthermore, it automatically recognizes typical signals of AE signals belonging to each group,
The time-dependent change in the number of occurrences of the same signal is output in real time, and from the output results, a phenomenon that is developing inside the ground is estimated, and that phenomenon is often seen in the initial stage when the ground collapses. By judging whether it is a phenomenon that occurs just before the collapse, the stability of the ground is evaluated correctly.

[0008]

EXAMPLES Next, examples shown in the drawings, in which the present invention is applied to cutting work, will be described. 1 is a ground, 2 is a cut slope, 3 is an AE sensor inserted in the ground, 4 is a wave guide,
Reference numeral 5 is a filling mortar for fixing the AE sensor, 6 is an underground displacement observing hole, 7 is a ground surface displacement meter, and 8 is a slip surface.

The AE signal captured by the AE sensor 3 is converted into an electric signal, input to the signal processing device 9 for measurement, input to the personal computer 10, and the oscilloscope 11 observes the waveform of the AE signal. .. Then, several AE parameters calculated by the signal processing device 9 are combined, and a dimensionlessized value is plotted on the horizontal axis as shown in FIG.
ram).

Generally, when different destruction mechanisms occur in the ground 1, the signal characteristics are different,
In the histogram, A group, B group, C
Groups are formed. Thus, the AE signal (AE count number) that is most frequently generated in each of the groups A, B, and C is shown in FIG.
A, Nb, Nc are considered, and the change of each group A, B, C is estimated from the change of each representative value Na, Nb, Nc with time. Each group represents physical phenomena inside the ground, group A shows signals due to local cracks and deformations that appear in the early stage of ground collapse, and group B is operating at the construction site. It is assumed that the signals of heavy machinery and the like are shown, and the group C represents the signal when the slip surface 8 starts to be formed and the ground is greatly deformed. And the stability of the ground can be evaluated correctly from the change of these groups.

In the example shown in the figure, since the signal of the C group starts to increase rapidly, it can be predicted that the ground collapse will occur very soon.

[0012]

According to the present invention, in AE measurement of natural ground, AE signals having different generation factors are grouped,
Since the destruction phenomenon inside the natural ground is estimated from the number of representative AE signals generated in each group, it becomes possible to distinguish the cause of AE generation, and the change in the destruction behavior inside the natural ground that changes moment by moment. Can be known in real time. In addition, since noise from heavy machinery at the construction site can be identified, it is possible to remove from the measured AE signals those signals that are not directly related to the destruction behavior of the ground. The stability of can be evaluated.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a state of implementation of a method for evaluating a natural ground by AE measurement according to the present invention.

FIG. 2 shows a histogram of an AE signal.

FIG. 3 is an explanatory diagram showing changes over time of the representative value of each group of AE signals.

[Explanation of symbols]

 1 Natural ground 3 AE sensor 8 Slip surface 9 Signal processing device 10 Personal computer 11 Oscilloscope

Claims (1)

[Claims] 1. A generated in association with the internal fracture behavior of natural ground
In the ground evaluation method that captures E sound, converts it to an electric signal, and measures and analyzes it, we group the AE signals with different generation factors, and change the number of representative AE signals generated in each group. , A method for evaluating a ground by AE measurement, which is characterized by estimating a fracture phenomenon inside the ground.