JPS59143930A - Large type wall surface stress gage - Google Patents

Abstract

PURPOSE:To provide a large gage in a simple constitution at a relatively low cost and to detect the vertical stress and horizontal stress, which are yielded in a retaining wall without interference each other, at the same time accurately, by connecting one end of each load cell to a pressure receiving plate rigidly, connecting the other end thereof to a main body rigidly, and detecting the vertical stress and the horizontal stress yielded at the wall surface of the retaining wall without interference each other. CONSTITUTION:When a force is applied in the vertical direction to a pressure receiving plate 2, a beam 1a of a load cell 1 is bent in the direction (y) with a connecting part 1f that is rigidly connected to a main body 3 as a fixed end. Strain gages SG5-SG8, which are attached to the bottom surfaces of holes 1d and 1e that are vertical to the pressure receiving plate 2, detect the shearing strain that is the vertical component with respect to the pressure receiving plate 2. The electrical signal proportional to the strain is outputted. At the same time, the beam 1a is bent in the direction (x) by the horizontal force with respect to the pressure receiving plate 2, i.e., the frictional force yielded on the pressure receiving surface of the pressure receiving plate 2. Strain gages SG1-SG4, which are attached to the bottoms of holes 1b and 1c that are the horizontal surface with respect to the pressure receiving plate 2, detect the shearing stress that is the horizontal component with respect to the pressure receiving plate 2. Then, the electrical signal proportional to the strain is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a large wall surface that is embedded and fixed in a retaining wall made of concrete, etc., and used to detect vertical stress (earth pressure) and horizontal stress (frictional stress) that the retaining wall surface receives from earth and sand, etc. It concerns a psychocardiometer.

Conventionally, as a wall soil pressure meter that measures the stress in the vertical direction to the wall surface, for example, the patent application filed in 1973 by the applicant of the present application has been proposed.
There is No. 6-132165. This conventional wall soil pressure gauge is
A pressure receiving plate with high rigidity and a diaphragm with low rigidity formed at one end of a highly rigid strain tube are connected via a transmission rod,
The pressure receiving plate and the side circumferential portion of the strain tube are connected via a circular plate having elasticity and low rigidity, and the other end of the strain tube and the mounting portion having high rigidity are connected to each other in the shape of a bottomed cylinder having a flange. The pressure receiving plate and strain cylinder are housed in the bottomed cylindrical case via watertight means by attaching the bottom part of the case and exposing the pressure receiving surface of the pressure receiving plate. The load is transmitted to the diaphragm of the strain tube via the transmission rod, and the amount of strain generated in the diaphragm is converted into an electrical output by a strain gauge attached to the diaphragm and taken out. .

In addition, as a measuring device for horizontal stress on the wall surface,
For example, as disclosed in JP-A-51-124.481, it consists of an outer box and an inner box placed inside the outer box, and the inner box is free in the direction parallel to the friction surface with respect to the outer box. It is supported by a ball bush or chain so that the movement in the direction perpendicular to the friction surface is restricted.
In addition, in the direction in which the inner box moves, a load cell that directly detects the frictional force is installed in the inner box, and a friction force measuring device is installed in the outer box that includes a bearing screw that contacts the load cell and resists the frictional force together with the load cell. Proposed.

However, these conventional earth pressure gauges or friction force measuring devices measure only stress in the vertical or horizontal direction, and cannot measure stress in both directions at the same time.

Furthermore, as another conventional example, a displacement plate (friction plate) and a detection part are integrated into a detection block, and the detection part is formed into a thin plate shape that is easily deflected in the friction direction, and a strain gauge is attached to the thin plate part. A friction force meter has been proposed in which the detection block is loosely fitted into the case and one end is fixed to the bottom of the case (Proceedings of the Japan Society of Mechanical Engineers, No. 44).
(See Vol. 381, pp. 1778-1788).

However, since this friction force meter uses a bending mechanism for the strain detection mechanism, the amount of displacement is large, and since the material of the friction member is different from that of the retaining wall, accurate friction stress cannot be determined. In addition to the problems, the structure is complex and difficult to machine, so only small pieces can be obtained.
In particular, it is impossible to apply the present invention to a large wall stress meter having a large pressure receiving area (for example, 1->) due to machining and assembly operations.

The present invention has been developed in view of these circumstances, and has a simple configuration that allows for relatively inexpensive and large-scale expansion, as well as simultaneous and highly accurate control of vertical stress and horizontal stress occurring in a retaining wall without interfering with each other. The purpose is to provide a large wall stress meter that can detect stress.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a front view showing the configuration of an embodiment of a large wall stress meter according to the present invention, FIG. 2 is a sectional view taken along the line A-A in FIG. FIG. 2 is a perspective view showing the configuration of an embodiment of a two-component beam type load cell that is a component.

In the case of the embodiment shown in FIG. 1 and FIG.
It consists of two-component beam type load cells (hereinafter simply referred to as load cells) 1, a pressure receiving plate 2, a main body 3, and a backing 4 for sealing.

Here, the load cell 1 has a square cross section (
A hole 1b and an IC having the same depth in the vertical direction (perpendicular to the pressure receiving plate 2 described later) from the upper and lower surfaces are bored in the middle part of the beam 1a, which has a rectangular shape (sometimes rectangular). Strain gauge 8G1 on the bottom of each IC
．． S02 and SG3.804 are bonded together,
It is attached. Strain gauge 8G1 and 802,803
and SG4 are ±45° to the longitudinal axis of beam 1a.
It is attached in the direction of forming. In addition, in the hole 1b of the beam 1a, holes 1d and te of equal depth in the left and right direction (horizontal direction to the pressure receiving plate) are bored from the left and right sides of the beam 1a in the middle part slightly away from the IC. Strain gauges SG5, SG6 and J? are placed on the bottom of 1d and 1e, respectively. 8G
7.8G8 is ±45 with respect to the longitudinal axis of beam 1a.
It is attached in a direction that forms an angle. Then, the lower surface of one end of the beam 1a is slightly protruded to connect the connecting portion 1 to the main body 3, which will be described later.
f, and the upper surface of the other end of the beam 1a is slightly protruded to form a connecting portion 1g to the pressure receiving plate 2. In this case, nickel chromium molybdenum steel is used as the material for the beam 1a, but the material is not limited thereto.

The pressure receiving plate 2 has a rectangular plate shape as shown in FIGS. 1 and 2, and has a reinforcing lip (not shown) provided on the steel plate to increase rigidity, and has a concave portion on the pressure receiving portion 2a side. 2b is formed, and a retaining wall surface material, particularly a material having the same coefficient of friction, is attached to the inside of this concave portion 2b. In this embodiment, concrete 1-5 is poured into the recessed portion 2b.

The main body 3 has a box shape with an opening at one end so that the load cell 1 and the pressure receiving plate 2 can be housed therein, and the pressure receiving plate 2 is fitted into the opening with a predetermined gap. The load cell mounting portions 3b and 3C are sized to meet the requirements and are provided at four cylindrical locations on the bottom portion 3a.

3d and 3e are firmly connected to the connecting portion 1f of the beam 1a by bolting or welding. The same material as that attached to the surface of the pressure receiving plate 20, in this case concrete l-6, is also cast on the surface side of the main body 30, and these concretes 1-5 and 6 are formed on the same plane. has been done.

The sealing backing 4 is for sealing the gap 7 created between the outer periphery of the pressure receiving plate 2 and the inner periphery of the opening of the main body 3, and is made of a flexible material such as rubber, for example. 7
One side of the backing press plate 8 is fixed to the peripheral edge of the pressure receiving plate 20, and the other side is
It is fixed to the main body 3 with a backing press plate 9. The pressing plates 8 and 9 are pressed against the pressure receiving plate 2 and the main body 3 by tightening screws (not shown).

FIG. 4 is a sectional view showing a wall stress meter according to the present invention embedded in a retaining wall.

In the figure, the wall stress meter includes the surface of the pressure receiving plate 2 and the main body 3.
It is buried in the concrete retaining wall 10 so that its surface is flush with the pressure receiving surface Oa of the concrete retaining wall 10. Although the example in which one wall stress meter is installed is shown in FIG. In some cases, multiple units may be installed in a vertical and vertical pattern.

Next, the operation of the embodiment having such a configuration will be explained. It is assumed that earth and sand are deposited on the pressure receiving surface 10a side of the retaining wall 10. Now, when the accumulated soil force rises or sinks, vertical and horizontal forces are transmitted to the pressure receiving plate 2 via the concrete 5. When a vertical force is applied to this pressure receiving plate, the beam 1a of the load cell 1 whose connecting portion 1g is firmly connected to the pressure receiving plate 2, with the connecting portion 1f firmly connected to the main body 3 as a fixed end, X shown in the third diagram
be bent in the direction Then, the strain gauges 5C15 to S'G8 attached to the bottom surfaces of the holes id and te, which are surfaces perpendicular to the pressure receiving plate 2, detect the shear strain of the vertical component to the pressure receiving plate 2 and respond to the applied force. Outputs a proportional nuisance signal. At the same time, the beam la is bent in the X direction in FIG. Strain gauges 801 to SG4 attached to the bottom of the IC in a certain hole Jb detect horizontal component shear strain on the pressure receiving plate 2, and output an electric signal proportional to the frictional force acting on the pressure receiving plate 2. In the case of this embodiment, four load cells 1 are installed at four corners between the pressure receiving plate 2 and the bottom 3a of the main body 3, and each load cell 1 has a shear strain in a direction perpendicular to the pressure receiving plate 2. There are 4 strain gauges SG5 to SG8 for detection.
Strain gauge SG for horizontal shear strain detection
1 to 8G4 are attached, each forming a well-known Wheatstone bridge circuit, and these Wheatstone bridge circuits are connected in parallel to obtain shear strain in the vertical and horizontal directions. Therefore, according to this embodiment, even if a local eccentric load is applied to the pressure receiving plate 2 or the stress distribution is uneven depending on the position within the pressure receiving plate 2, each of the four load cells 1 Although each output strain is detected differently, the sum of the four outputs always detects the indicated value as a stable integral value within the area of the pressure receiving plate.

This is true for strain detection both in the vertical and horizontal directions with respect to the pressure receiving plate 2.

In addition, the strain detection in this embodiment is different from the detection of compressive or tensile strain due to bending, and is to detect shear strain, so the output strain changes depending on the axial length of the load cell 1. The advantage is that nothing happens. Since the strain gauges that detect the shear strain in the vertical and horizontal directions are attached to the mutually perpendicular surfaces of the beam 1a of the load cell 1, the vertical stress and horizontal stress on the pressure receiving plate increase and decrease, respectively. It is also possible to perform highly accurate measurements without mutual interference. Incidentally, in this example, the interference was able to be suppressed to within 0.5%.

Further, according to the above embodiment, since the recessed portion 2b is formed on the pressure receiving surface 2a side of the pressure receiving plate 2, this recessed portion is made of a material (concrete 1-, Mortar, etc.) can be attached. Therefore, the frictional stress that would actually occur on the retaining wall surface can be determined with high precision. Furthermore, since the above embodiment does not have a mechanical friction part, it is possible to obtain stable measurement data over a long period of time with small hysteresis and good repeatability.

Note that the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications within the scope of the gist of the present invention.

For example, retaining walls are not only made of concrete but may also be made of mortar or other materials, and in such cases, the surface of the pressure receiving plate 2 and the surface of the main body 30 may be made of the materials used therein. It is sufficient to attach a material having almost the same coefficient of friction.

In addition, although the example using four load cells was described, three
or 5 or more.

Furthermore, the sealing backing 4 is not limited to a plate-shaped one.
A deformation absorbing layer made of a rubber compound (for example, chloroprene rubber with sealed cells) that does not restrict the movement of the pressure plate 2 may be provided between the pressure plate 2 and the main body 30 (in the gap 7).

As described in detail above, the present invention has a simple structure that is easy to process and assemble, so it can be made larger at a relatively low cost, and the vertical stress and horizontal stress generated in the retaining wall can be prevented from interfering with each other. Therefore, it is possible to provide a large-sized wall stress meter that can detect the stress at the same time and with high precision without having to do so.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the configuration of an embodiment of a large wall stress meter according to the present invention, FIG. 2 is a sectional view taken along the line A-A in FIG. 1, and FIG. 3 is a configuration of the present invention. FIG. 4 is a perspective view showing the configuration of an embodiment of a two-component beam type load cell as an element.
FIG. 2 is a sectional view showing a state in which a large wall stress meter according to the present invention is embedded in a retaining wall. 1... Two-component beam type load cell, 1a... Beam, 1b to 1e... Hole,
If, Ig...Connecting portion, 2...Pressure plate, 2a...Concave portion, 3...Main body,
3b to 3e...Two-component beam type load cell mounting part,
4...Backing, 5,6...Concrete 1-17...Gap, 0...Concrete retaining wall.

Claims (1)

[Claims] (11) In a large-scale wall dynamometer for measuring vertical stress and horizontal stress on the retaining wall, strain gauges for shear force detection are installed on two surfaces parallel to the longitudinal axis of the beam and perpendicular to each other. a plurality of two-component beam type load cells attached to each other; a highly rigid pressure receiving plate having a pressure receiving surface attached to a material having a friction coefficient substantially the same as that of the retaining wall; and the load cell and the pressure receiving plate. and a highly rigid main body that is embedded and fixed in the retaining wall, and has a flexible backing that seals a gap that occurs between the pressure receiving plate and the main body, One end of each load cell is firmly connected to the pressure receiving plate, and the other end is firmly connected to the main body, so that vertical stress and horizontal stress on the wall surface generated in the retaining wall can be detected simultaneously without interference with each other. A large wall dynamometer that is characterized by: