JP3733528B2 - Bender element installation jig - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bender element installation jig, and more particularly to a bender element installation jig used for facilitating the mounting of a bender element to a measurement object such as the ground.
[0002]
[Prior art and problems to be solved by the invention]
As a method for measuring the shear wave velocity V _s or the density wave velocity V _p of a solid material such as ground or concrete, a bender element having a structure in which a piezoelectric vibration element is supported by an acrylic pedestal as shown in FIGS. Measurement methods are known. FIG. 6A shows a basic type of a rectangular parallelepiped acrylic base block 51 to which a piezoelectric ceramic vibration element 52 is fixed. The vibration element 52 has a bimorph type cantilever structure having a beam length (X) in which one end 52 a is fixedly supported by the base block 51. FIG. 6B shows the bender element 50 measured and installed at the intermediate point. As shown in the figure, a vibrating element 52S as an oscillating portion is fixed to the upper surface 51a of the base block 51, and a vibrator 52R as a receiving portion is fixed to the lower surface 51b.
[0003]
FIG. 7 shows a method of measuring the shear wave velocity of the ground using the bender element shown in FIG. As shown in FIG. 7, the bender elements 50S and 50R are embedded in the ground separated by a predetermined distance L, a shear wave is transmitted from one bender element 50S, and a shear wave is received by the other bender element 50R. By dividing the distance L between the bender elements by the propagation time (delay time) of the shear wave, the shear wave velocity of the target ground is calculated. At this time, in order to accurately measure the shear wave velocity V _s or the dense wave velocity V _p , the vibration of the vibration element is reliably transmitted to the measurement material such as the ground to be measured, and the distance between the bender elements is accurately set. It is important to. Furthermore, in order to reliably transmit vibration to the measurement material, it is important that the vibration element is in close contact with the ground surface as the measurement material and that the acrylic pedestal for fixing the vibration element does not resonate with the vibration element.
[0004]
Conventionally, in the case of measurement using a bender element, the bender element is attached and fixed to the surface of the measurement material 60 in the procedure as shown in FIGS. First, a groove 61 for making the vibration element 52 only into the measurement material is created. Next, the vibration element 52 of the bender element 50 is inserted into the groove 61. Furthermore, it is necessary to fix the acrylic pedestal in order to reliably transmit the vibration of the vibration element 52 to the measurement material 60 and to prevent the acrylic pedestal itself from vibrating. For example, as a method of fixing the acrylic pedestal, a weight 62 is placed on the bender element 50 as shown in FIGS. 9A and 9B, or a wire 64 or the like is stretched from the anchor 63 and fixed. .
[0005]
However, such a fixing method is not only troublesome, but also forms a groove for fixing the bender element, and thus damages the surface of the measurement material. Each time the measurement location is changed, the distance between the bender elements must be set accurately. In view of the above background, there has been a demand for a means that can securely install the bender element simply by placing it on the material surface without damaging the measurement material. Also, it has been required to keep the distance between the bender elements constant at a predetermined value in a plurality of measurements.
[0006]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a bender element installation jig that solves the above-mentioned problems of the prior art and can easily arrange and fix a bender element on the surface of a measurement material.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has a plurality of legs that can be adjusted to be separated from the measurement material, and projecting the legs toward the measurement material. It is characterized by comprising a base plate capable of fixing a bender element at a position.
[0008]
At this time, it is preferable that the leg portion is a bolt that is screwed at the corner portion of the base plate so as to protrude to the measurement material side so that the protrusion length can be adjusted.
[0009]
Further, it is preferable that a plurality of bender element installation jigs at a predetermined distance are connected by a connector, and the shear wave velocity is measured between the bender elements of the bender element installation jig.
[0010]
At this time, the connector is preferably a member having a bending rigidity of 100 kN · m ² or less, such as a wire cable.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a vendor element installation jig according to the present invention will be described with reference to the accompanying drawings. FIGS. 1A and 1B are perspective views showing the front and back surfaces of a bender element installation jig 10 according to the present embodiment. As shown in the figure, the bender element installation jig 10 includes a base plate 11 made of a substantially square metal plate and leg bolts 13 screwed into through screw holes 12 formed at four corners of the base plate 11. And a bender element 20 fixed at a predetermined position on the back surface side of the base plate 11 (the lower surface side during normal installation).
[0011]
Among these, the base plate 11 is made of a stainless steel plate having a thickness of 15 mm and a side of 160 mm having a rigidity and a mass that do not cause deflection or the like in use in the present embodiment. Further, a stainless steel bolt having a length of 60 mm is also used for the leg bolt 13. An adjustment nut 14 is screwed to the head of the leg bolt 13 so as to be positioned and fixed. The bender element 20 is screwed to a predetermined position on the back surface of the base plate 11 with a mounting screw (not shown). On the other hand, a substantially U-shaped handle 15 is fixed to a central position on the surface (upper surface side during normal installation). The handle 15 is used not only for transporting the bender element installation jig, but also for ease of use when applying a pressing force for crimping the measurement material upon installation, and an anchor for the wire cable 25 as a connecting tool described later. Also serves as a part.
[0012]
The base plate 11 holds the bender element 20 and, when the bender element installation jig is installed on the surface of the measurement material as shown in FIG. 2, the vibration element 22 of the bender element 20 is measured by the total weight of the measurement material. It is set so that it has sufficient mass so that it may be crimped | bonded to the surface 2 of 1 and the role which suppresses the vibration of the base 21 will be played. For example, in the present embodiment, the mass of 3 kg is attached to the type in which one bender element 20 to be attached as the mass of the base pre is attached. Therefore, when two bender elements 20 are attached, the mass of the base plate 11 is 6 kg. The mass of one base plate 11 at this time can be set to about 0.1 to 20 kg. Therefore, it is preferable that the number of stacked base plates 11 is increased or decreased according to the number of vendor elements 20 to be attached, or the plate thickness per sheet is increased.
[0013]
The leg bolt 13 can arbitrarily set the contact angle of the vibration element 22 to the surface of the measurement material by appropriately adjusting the length of the screw portion 13a. Further, the pressing force of the vibration element 22 on the surface of the measurement material can be adjusted within a range not exceeding the mass of the jig.
[0014]
3 is a perspective view showing an example in which the position of the vibration element 22 attached to the back surface of the base plate 11 is changed. For example, as shown in FIG. 3A, the strength (pressing force) for pressing the vibration element 22 against the measurement material can be adjusted with high accuracy by attaching the bender element 20 to the substantially central position of the base plate 11. . By arbitrarily determining the mounting direction of the bender element 20, the direction of vibration generated by the vibration element 22 can be arbitrarily determined (see FIG. 3B). When a plurality of bender elements 20 are attached, the data may be calibrated by attaching the bender elements 20 having the same sensitivity in parallel. Each bender element 20 can be easily attached by using attachment holes formed in the base plate 11 at a predetermined pitch in advance.
[0015]
4 shows a modification of the base plate 11 in which the planar shape of the base plate 11 is substantially triangular, and the base plate 11 is supported by two leg bolts 13 and a bender element 20. In such a configuration, the installation jig is supported at three points, that is, two points of the leg bolt 13 and one point of the bender element 20 on the surface of the measurement material. Therefore, the vibration element 22 can be reliably bonded to the surface of the measurement material without adjusting the leg length of the leg bolt 13. Thereby, the vibration element 22 can be adhered to the surface of the measurement material with a constant pressing force. Therefore, the shear wave velocity V _s or the dense wave velocity V _p can be measured under the same pressing condition even if the measurement location is changed.
[0016]
FIG. 5 shows an example of use in which two bender element installation jigs 10 are connected by a wire cable 25 as a connecting tool. The wire cable shown in the figure is a resin-coated steel cable having a wire diameter of 1 mm, has sufficient flexibility, and has a bending rigidity of 100 kN · m ² or less. Thus, the distance between the bender elements 20 can always be kept constant by connecting the two bender element installation jigs. Therefore, even when the measurement position is moved, when the wire cable is sufficiently stretched, the distance between the bender element installation jigs can be accurately maintained, and the shear wave velocity V _s or the same distance can be maintained. the compressional wave velocity V _p can be measured. In the present embodiment, the handle 15 is a fixed end of the wire cable, but a dedicated anchor portion can be formed on the base plate 11. It is also possible to connect 3 or more n units and set each cable length as appropriate, or to set all of them equal to each other so that the position of each bender element 20 forms the apex of a regular n-gon. is there.
[0017]
【The invention's effect】
As described above, according to the present invention, the installation of the bender element can be completed simply by placing it on the surface of the measurement material without damaging the measurement material, and the material of the vibration element can be changed even if the measurement location is changed. Measurement conditions such as the pressing force on the surface and the distance between bender elements can always be reproduced, and the contact angle and pressing force of the vibration element to the surface of the measurement material can be freely adjusted. It is possible to measure the shear wave velocity V _s or the dense wave velocity V _p with high accuracy.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of a bender element installation jig according to the present invention.
FIG. 2 is a front view showing an installation state of the bender element installation jig of FIG. 1;
FIG. 3 is a perspective view showing an example of an attachment position of a bender element to a base plate.
FIG. 4 is a perspective view showing a modification of the base plate.
FIG. 5 is a side view showing a connected state of a bender element installation jig.
FIG. 6 is a perspective view showing a configuration example of a bender element.
FIG. 7 is a schematic cross-sectional view showing an example of shear wave velocity measurement by a bender element.
FIG. 8 is an enlarged view showing an example of attaching a conventional bender element to a measurement material.
FIG. 9 is an enlarged view showing an example of fixing a conventional bender element to a measurement material.
[Explanation of symbols]
1 Measurement Material 10 Bender Element Installation Jig 11 Base Plate 13 Leg Bolt 20 Bender Element 21 Base 22 Vibration Element 25 Wire Cable

Claims (4)

From a base plate having a plurality of legs that can be separated from the measurement material, and projecting the legs toward the measurement material, and fixing the bender element at a predetermined position on the surface on the leg side Bender element installation jig characterized by The bender element installation jig according to claim 1, wherein the leg portion is formed of a bolt that protrudes toward the measurement material side and is screwed to a corner portion of the base plate so that a protrusion length can be adjusted. 2. A bender element according to claim 1, wherein a plurality of bender element installation jigs at a predetermined distance are connected to each other by a connector, and a shear wave velocity is measured between the bender elements of the bender element installation jig. Installation jig. 4. The bender element installation jig according to claim 3, wherein the connector is a member having a bending rigidity of 100 kN · m ² or less.

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