JPH11132838A - Vibration detection apparatus and measurement method of ground vibration propagation velocity thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce influence of disturbance in harsh environments by placing a cover, which covers ground and an outer region of a vibration sensor, in non-contact with the vibration sensor. SOLUTION: A vibration detection apparatus comprises a dome shaped cover 2 is covered the whole of an outer region of a vibration sensor 1 together with ground and is non-contacted with the vibration sensor 1. The cover 2 is formed with a transparency acrylic plastic plate, and a wire 3 transmits a signal from the vibration sensor 1 is led from holes 2 to an outside and connected to a receiver. The wire 3 is placed with enough looseness so that vibration does not propagate from the cover 2 to the vibration sensor 1. Since the cover 2 prevents the vibration sensor 1 from being directly exposed to wind, rain and pebble stones, influence of disturbance is reduced in harsh environments.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration detecting device for detecting ground vibration and a method for measuring the propagation speed of ground vibration waves using the same.

[0002]

2. Description of the Related Art Conventionally, seismic signals have been detected by detecting ground vibrations, and physical properties such as allowable bearing capacity of the ground have been measured. In this case, the necessary signal is the seismic signal itself, and only the surface wave (Rayleigh wave) propagated from the shaker, and vibration other than the intended signal appears as noise.

[0003]

However, when a vibration detecting device currently on the market is exposed to wind and rain, pebbles, sand, dust, etc., which fly due to the vibration or the wind due to the wind and rain, hit the vibration detecting device, and the vibration is detected. Became noise, leading to measurement errors. In particular, in the case of a vibration detection sensor that detects acceleration, the above-described impact has caused a large measurement error. When the measurement is completed in a short time, the measurer can protect the vibration detecting device with an umbrella or the like, but when the measurement is performed for a long time, such measures are not taken.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and to provide a vibration detecting device which is hardly affected by disturbance even in a bad environment, and a method for measuring the propagation velocity of ground vibration waves using the vibration detecting device. Aim.

[0005]

A vibration detecting apparatus according to claim 1 (hereinafter referred to as "the present invention 1") is provided with a vibration sensor for detecting vibration of the ground and a non-contact with the vibration sensor. It consists of a cover that can cover the outer periphery of the vibration sensor together with the ground when installed.

The material of the cover used in the present invention 1 is not particularly limited, and examples thereof include a metal material and a synthetic resin material.

[0007] The shape of the cover used in the present invention 1 is not particularly limited, and may be, for example, a hemisphere, a prism (a rectangular parallelepiped,
Cubic), cylindrical, pyramidal, conical, and the like.

The cover used in the first aspect of the present invention preferably covers the entire outer periphery of the vibration sensor together with the ground, but this is not limited as long as it is not affected by wind and rain. Further, this is not the case even when the unevenness of the ground is large and it is difficult to cover the entire outer periphery of the vibration sensor.

In the present invention 1, the number of vibration sensors covered by one cover may be one or more. Further, the vibration sensor may be partially embedded in the ground. In this case, the cover may cover the entire outer periphery of the portion of the vibration sensor exposed from the ground.

According to a second aspect of the present invention, in the vibration detecting apparatus according to the first aspect of the present invention, at least a part of the cover is formed of a damping material.

Examples of the vibration damping material used in the present invention 2 include rubber and synthetic resin foam.
The vibration damping material may be laminated on a metal material or a synthetic resin material.

In the second aspect of the present invention, at least a part of the cover is formed of the damping material, but the entire cover may be formed of the damping material. In particular, the wiring section for transmitting the signal from the vibration sensor to the receiver has a high possibility of contact with the cover, and therefore, it is effective to form the wiring section with a vibration damping material. However, this is not particularly necessary when the wiring is sufficiently protected in advance by a damping material such as rubber.

[0013] In the second aspect of the present invention, the contact portion between the cover and the ground may be formed of a damping material. In this way, the impact on the cover is prevented from being transmitted to the vibration sensor via the ground, and even when the ground is uneven, the elasticity of the damping material allows the entire outer periphery of the vibration sensor to be covered. Can be covered.

According to a third aspect of the present invention, there is provided a method for measuring the propagation velocity of a ground vibration wave, wherein the vibration detecting device according to the first or second aspect of the present invention is attached to the ground to be measured.
A vibration wave propagated by vibrating the ground is detected by the vibration detection device, and a propagation speed of the vibration wave of the ground is calculated from the vibration wave.

In order to calculate the propagation speed of the vibration wave on the ground, for example, the phase difference Δt between the vibration waves detected by the two vibration detection devices is obtained, and the distance between the vibration detection devices is determined by the phase difference Δ
It can be obtained by dividing by t. In order to obtain the phase difference Δt, the time difference at which the cross-correlation coefficient between the vibration waves detected at the two vibration detection distances becomes the maximum value is obtained by, for example, fast Fourier transform (FFT) or frequency / wave number spectrum analysis. it can.

In this case, by detecting only the vertical component (Rayleigh wave) of the vibration wave, the allowable supporting force of the ground and the shear modulus can be obtained.

[0017]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an example of the vibration detecting device according to the first embodiment of the present invention. In FIG. 1, 1 is a vibration sensor,
2 is a cover, 3 is wiring. As shown in FIG. 1, a vibration detection device includes a vibration sensor 1 for detecting ground vibration.
And a hemispherical cover 2 that is provided in non-contact with the vibration sensor 1 and covers the entire outer periphery of the vibration sensor 1 together with the ground. The cover 2 is formed of a transparent acrylic plate, and a wiring 3 for transmitting a signal from the vibration sensor 1 is not shown from the vibration sensor 1 through a hole 2 a provided in the cover 2. Connected to receiver. The wiring 3 is sufficiently slackened so that no vibration is transmitted from the cover 2 to the vibration sensor 1.

FIG. 2 is a sectional view showing another example of the vibration detecting device according to the first embodiment of the present invention. In FIG. 2, 1 is a vibration sensor, 2 is a cover, 3 is a wiring, and 5 is an insertion part to the ground. As shown in FIG. 2, the vibration detecting device includes a vibration sensor 1 that detects vibration of the ground, a hemispherical cover 2 that is provided in non-contact with the vibration sensor 1, and covers the entire outer periphery of the vibration sensor 1 together with the ground. And an insertion portion 5 for insertion into the ground. The cover 2 is formed of a transparent acrylic plate, and the vibration sensor 1
From the vibration sensor 1 to transmit the signal from
A hole 2a provided in the cover 2 is connected to a receiver (not shown). The wiring 3 is sufficiently slackened so that no vibration is transmitted from the cover 2 to the vibration sensor 1.
From the vibration sensor 1, an insertion portion 5 into the ground protrudes, and is inserted into the ground when it is mounted on the ground to be measured.

FIG. 3 is a perspective view showing an example of the vibration detecting device according to the second embodiment of the present invention. In FIG. 3, 1 is a vibration sensor,
2 is a cover, 3 is a wiring, and 4 is a damping material. As shown in FIG. 3, the vibration detection device includes a vibration sensor 1 that detects vibration of the ground, a hemispherical cover 2 that is provided in non-contact with the vibration sensor 1 and covers the entire outer periphery of the vibration sensor 1 together with the ground. Consists of The cover 2 is formed of a transparent acrylic plate, and a wiring 3 for transmitting a signal from the vibration sensor 1 is not shown from the vibration sensor 1 through a hole 2 a provided in the cover 2. Connected to receiver. The wiring 3 is sufficiently slackened so that no vibration is transmitted from the cover 2 to the vibration sensor 1. A ring 4 made of a rubber damping material is inserted between the cover 2 and the ground.

FIG. 4 is a perspective view showing another example of the vibration detecting device according to the second embodiment of the present invention. In FIG. 4, 1 is a vibration sensor, 21 is a cover, and 3 is a wiring. As shown in FIG. 2, the vibration detecting device according to the second aspect of the present invention includes a vibration sensor 1 for detecting vibration of the ground, and a And a cover 21. The cover 21 is formed of a material in which rubber is laminated on a surface of a steel material with an adhesive. Also, from the vibration sensor 1, the vibration sensor 1
From the vibration sensor 1 to transmit the signal from
A hole 21a provided in the cover 21 is connected to a receiver (not shown). The wiring 3 is sufficiently slackened so that no vibration is transmitted from the cover 21 to the vibration sensor 1.

FIG. 5 is a sectional view showing still another example of the vibration detecting device according to the second embodiment of the present invention. In FIG. 5, 1 is a vibration sensor, 2 is a cover, 3 is a wiring, 41 is a vibration damping material, and 5 is a part to be inserted into the ground. It is. As shown in FIG. 2, the vibration detecting device according to the second aspect of the present invention includes a vibration sensor 1 for detecting vibration of the ground, and a And a cover 21. The cover 21 is formed of a material in which rubber is laminated on a surface of a steel material with an adhesive. Also, from the vibration sensor 1, the vibration sensor 1
From the vibration sensor 1 to transmit the signal from
A hole 21a provided in the cover 21 is connected to a receiver (not shown). The wiring 3 is sufficiently slackened so that no vibration is transmitted from the cover 21 to the vibration sensor 1. A ring 41 made of a rubber damping material is inserted between the cover 2 and the ground. Further, from the vibration sensor 1, an insertion portion 5 into the ground protrudes, and is inserted into the ground when it is attached to the ground to be measured.

In order to calculate the propagation velocity from the ground vibration wave obtained as described above, for example, the mutual phase relationship between the vibration waves detected by two or more vibration detection devices of the present invention 1 or 2 can be used. The number can be obtained by obtaining the number by a fast Fourier transform (FFT) or the like, and dividing the distance between the vibration detecting devices by the phase difference Δt at which the value is maximized.

[0024]

The vibration detecting device according to the first aspect of the present invention includes a vibration sensor for detecting ground vibration and a cover provided in non-contact with the vibration sensor and covering the outer periphery of the vibration sensor together with the ground. Since the sensor does not directly hit the vibration sensor, the device is less affected by disturbance even in a poor environment.

According to the vibration detecting device of the second aspect of the present invention, at least a part of the cover is formed of a damping material in the first aspect of the present invention,
Since the vibration is not transmitted to the vibration sensor via the wiring or the ground, the influence of the disturbance is further reduced even in a bad environment.

According to a third aspect of the present invention, there is provided a vibration detecting apparatus, wherein the vibration detecting apparatus according to the first or second aspect of the present invention is mounted on a ground to be measured, and a vibration wave propagated by vibrating the ground is detected by the vibration detecting apparatus. Since the propagation velocity of the vibration wave of the ground is calculated from the wave, the propagation velocity of the vibration wave of the ground can be accurately measured without being affected by disturbance, and the allowable bearing force and shear elasticity of the ground can be measured. Physical properties such as coefficients can be accurately measured.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an example of a vibration detection device according to the first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another example of the vibration detecting device according to the first embodiment of the present invention.

FIG. 3 is a perspective view illustrating an example of a vibration detection device according to a second embodiment of the present invention.

FIG. 4 is a perspective view showing another example of the vibration detection device according to the second embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating still another example of the vibration detection device according to the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vibration sensor 2, 21 Cover 4, 41 Damping material

Claims (3)

[Claims] 1. A vibration sensor for detecting ground vibration,
A vibration detection device, comprising: a cover provided in a non-contact manner with the vibration sensor, the cover being capable of covering the outer periphery of the vibration sensor together with the ground when installed on the ground. 2. The vibration detecting device according to claim 1, wherein at least a part of the cover is formed of a damping material. 3. The vibration detecting device according to claim 1 or 2 is attached to a ground to be measured, and a vibration wave propagated by vibrating the ground is detected by the vibration detecting device, and the vibration of the ground is detected from the vibration wave. A method for measuring the propagation velocity of a ground vibration wave, comprising calculating a propagation velocity of a wave.