JPH10246724A - Underground elastic wave detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detector for acquiring much satisfactory detailed measured data as compared with prior art by simplifying an operation while largely reducing a cost in an underground elastic wave detector for detecting an elastic wave (AE wave) generated under the ground. SOLUTION: The underground elastic wave detector comprises a long cylinder 10 made of vinyl chloride inserted into an excavated hole, a plurality of elastic wave sensors 12 disposed at a suitable interval in the cylinder 10, a coupler 14 for coupling the sensors 12. In this case, the cylinder 10 is fully filled with liquid 16, and the wave generated under the ground is detected by the sensor 12 via a wall of the cylinder 10 and liquid 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underground elastic wave detecting device for detecting an elastic wave (AE wave) generated underground. This type of device is used for investigating and monitoring damage and destruction of foundations and slopes of structures.

[0002]

2. Description of the Related Art A solid rod or hollow rod of a predetermined length is prepared, and an elastic wave sensor (AE sensor) is provided on the outer surface or inside of the rod (waveguide rod). The waveguide is embedded in a borehole (solid bar) or driven into the ground (hollow bar)
The AE sensors are arranged at appropriate intervals in the longitudinal direction of the waveguide.

[0003] Frictional noise and destructive sound generated on a damaged or damaged portion of the foundation of the structure, a destructive surface or a discontinuous surface in the ground slope, reach the waveguide rod, and are detected by each sensor. The signals detected by these sensors are taken out to the ground and processed by a computer. As a result, the position and size of the sound source (damage in the case of a concrete pile on the foundation of a structure, the position and degree of a damaged portion / destruction in the case of a slope, The position and scale at which the friction and breakage of the discontinuous surface occur) are specified.

A waveguide rod (solid rod) provided with a sensor on the outer surface is buried and left as it is, and a waveguide rod (hollow rod) provided inside is pulled out and reused. is there.

[0005]

In the case of a waveguide rod (solid rod) in which the sensor and the waveguide rod are buried and left alone because the sensor is expensive, damage or destruction of the foundation or slope of the structure is made. The costs of investigating and monitoring such things are high. In the case of a reusable waveguide rod (hollow rod), for example, it is necessary to process the rod into a shape that is drawn down to the tip of the driving in order to be driven into the ground and then pulled out, and the rod is expensive. Furthermore, the number of reuses is limited. Therefore,
There are limits to cost savings.

The present invention has been made in view of the above circumstances, and an object of the present invention is to significantly reduce the cost required for investigating and monitoring damage or destruction of a foundation or a slope of a structure. An object of the present invention is to provide an underground elastic wave detection device.

[0007]

[Means for Solving the Problems]

1st invention (refer to FIG. 1) A long tubular body 10 made of vinyl chloride inserted into a borehole, a plurality of elastic wave sensors 12 disposed at appropriate intervals in the long tubular body 10, and each elastic wave sensor A connecting tool 14 for connecting the two;
The long cylindrical body 10 is filled with the liquid 16, and an elastic wave generated in the ground is detected by the elastic wave sensor 12 through the wall of the long cylindrical body 10 and the liquid 16. A second invention (see FIG. 1); a thin-walled long cylindrical body 10 made of vinyl chloride to be inserted into a drilling hole; and a plurality of elastic wave sensors 12 arranged at appropriate intervals in the long cylindrical body 10; It has a string body 14 for connecting the elastic wave sensors 12 and a winding machine 18 for winding and unwinding the string body 14. The long cylindrical body 10 is filled with water 16, and each elastic wave sensor 12 has a long length. An elastic wave suspended in the cylindrical body 10 and generated in the ground is detected by the elastic wave sensor 12 through the wall of the long cylindrical body 10 and the water 16.

[0008]

FIG. 1 shows an example of an underground elastic wave detecting apparatus. The apparatus has a long cylinder 10, a plurality of elastic wave sensors 12, and a connector 14, and the long cylinder 10 is filled with water 16. In this example, a thin-walled vinyl chloride pipe is used for the long cylindrical body 10, and the vinyl chloride pipe is bottomed by attaching a cap.

[0009] Thin-walled vinyl chloride pipes are widely distributed so as to be called "environmental pipes", and are excellent in economy. In addition, since it is lightweight, it is convenient for transportation and handling, and processing such as capping and cutting can be easily performed. Moreover, the acoustic impedance of vinyl chloride is very close to that of soil. For this reason, the incidence efficiency of the AE wave generated in the ground is high, and the AE wave is taken into the apparatus with good sensitivity.

Water has the property of transmitting AE waves without loss (it may be an organic liquid). Since the inside of the long cylindrical body 10 is filled with water 16, it is generated underground. A
The E wave reaches each sensor 12 at a sufficient level with little attenuation via the long cylinder 10 and the water 16. The water 16 does not leak because the long cylindrical body 10 has a bottom. Soil ground and water 16 where leakage of water 16 is unlikely
In the case of soil with a small amount of soil leakage or ground with high groundwater, the long cylindrical body 10 does not need to be bottomed (it can be replenished as necessary).

Incidentally, in the case of a position near the break point or the break point itself, the long cylindrical body 10 may be formed of a metal member. Each of the sensors 12 is connected by a connecting member 14, and in this example, a rope (string) is used for the connecting member 14. The sensors 12 are attached to the ropes 14 at appropriate intervals and suspended, and the signal lines of the sensors 12 are drawn out along the ropes 14 to the ground.

A hoist 18 is provided directly above the ground. The hoist 18 winds and rewinds the rope 14, and the operation adjusts the position of each sensor 12. The hoisting machine 18 is provided when the long cylindrical body 10 is considerably long. Not required if not long.

FIG. 2 illustrates the operation when the slope is monitored for collapse, and FIG. 3 illustrates the operation when the diagnosis of the concrete pile is performed. The AE wave generated at the damaged or damaged part of the device propagates through the ground and reaches the apparatus. Then, the light passes through the thin wall of the long cylindrical body 10 and the water 16 without being attenuated, and each sensor 12 detects this with high sensitivity.

The outputs of these sensors 12 are received by a computer 20 installed on the ground, and the computer 20 performs a measurement process using the received sensor signals to determine the stability of the slope, or to damage or break the concrete pile. Diagnose the condition of At the site, the installation position of the device is first determined. Usually, there are a plurality of installation positions.

The number of the long cylindrical bodies 10 for simultaneous measurement is prepared, and the required number of sensors 12 is also prepared. Then, drilling work is performed on all positions, and the long cylindrical body 10 is inserted into the vertical hole for simultaneous measurement. Since a thin-walled PVC pipe is used for the long cylindrical body 10, the long cylindrical body 10 is inserted into the vertical hole.
Is inserted manually. No heavy equipment is needed. The work is completed in a short time.

Next, earth shavings are buried between the vertical hole and the elongated cylinder 10, and water 16 is injected into the elongated cylinder 10 (see FIGS. 2 and 3). Further, the hoist 18 is installed immediately above the vertical hole, and the rope (14) is unwound while the sensors 12 are sequentially attached. The number and the mounting interval of the sensors 12 are changed according to the object, and the depth position is adjusted by operating the hoist 18.

Further, all the sensors 12 are connected to the computer 2
0, and causes the computer 20 to start the measurement process. When the measurement is completed, the sensors 12 are sequentially removed and collected while winding up the rope (14). When measuring at another position, move to that position and repeat the above operation. Finally, using all the measurement results, the computer 20 informs the computer 20 of the broken surface of the slope, the discontinuous surface, the damaged portion of the concrete pile, and the damaged portion. Calculate and specify the position and degree.

When the hole is inclined, a single bar or a long bar is used instead of the rope (14). As described above, no heavy equipment is required except for the drilling work, and the long cylindrical body (thin-walled PVC pipe) 10 and the water 16 can be easily and inexpensively obtained at any place, and the sensor 12 can be used repeatedly. , Cost can be greatly reduced.

Moreover, a long cylindrical body (thin-walled PVC pipe)
The 10 and the water 16 can be easily handled manually, thus greatly reducing the working time. In addition, since no heavy objects are carried, the maneuverability is greatly improved, and the work can be performed extremely safely. Further, since the mounting position and number of the sensors 12 can be freely changed, it is possible to acquire much better and detailed measurement data as compared with the related art.

In many cases, the long cylindrical body 10 is buried, but when the next investigation is scheduled, the opening is capped and left as it is. This may be extracted and reused.

[0021]

As described above, according to the present invention, it is possible to simplify the operation while greatly reducing the cost, and to obtain much better and more detailed measurement data than before. Become. There are many requests to confirm safety in preparation for collapse of rock at the tunnel entrance, debris flow disaster, collapse of buildings due to large earthquakes, etc., but the present invention is the most suitable to meet these requirements.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view of an apparatus to which the invention is applied.

FIG. 2 is an explanatory diagram of an operation when monitoring a slope collapse.

FIG. 3 is an explanatory diagram of an operation at the time of a concrete pile diagnosis.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Long cylindrical body (thin-walled PVC pipe) 12 Elastic wave sensor 14 Connector / string body (rope) 16 Water 18 Winding machine 20 Computer

Claims (3)

[Claims] 1. A long cylindrical body (10) inserted into a borehole,
The long cylindrical body (10) includes a plurality of elastic wave sensors (12) disposed at appropriate intervals in the long cylindrical body (10), and a connector (14) for connecting the elastic wave sensors (12). 10) is liquid (1)
6), the elastic wave generated in the ground
Acoustic wave sensor (12) through wall (0) and liquid (16)
An underground elastic wave detection device characterized by being detected by: 2. A long pipe body (10) made of vinyl chloride inserted into a borehole, a plurality of elastic wave sensors (12) arranged at appropriate intervals in the long pipe body (10), A connecting member (14) for connecting the wave sensor (12), wherein the long cylindrical body (10) is filled with the liquid (16), and elastic waves generated in the ground are covered with a wall of the long cylindrical body (10). And an underground elastic wave detection device which is detected by an elastic wave sensor (12) via a liquid (16). 3. A long, thin, bottomed, cylindrical body made of vinyl chloride inserted into a borehole, and a plurality of elastic wave sensors (12) arranged at appropriate intervals in the long cylindrical body (10). , A string (14) connecting the elastic wave sensors (12), and a string (1).
Winding machine (18) for winding and rewinding 4)
And the long cylindrical body (10) is filled with water (16);
Each elastic wave sensor (12) is suspended in the long cylindrical body (10), and elastic waves generated in the ground are transmitted through the wall of the long cylindrical body (10) and the water (16) by the elastic wave sensor (12). Detected,
An underground elastic wave detection device, characterized in that: