JPH0319495B2 - - Google Patents

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 is related to stress meters.

Conventionally, as a wall earth pressure meter for measuring stress in the vertical direction to a wall surface, there is, for example, Japanese Patent Application No. 56-132165 (Japanese Unexamined Patent Publication No. 58-34332) previously filed by the applicant of the present application. This conventional wall soil pressure gauge connects a highly rigid pressure receiving plate and a relatively rigid diaphragm formed at one end of a highly rigid strain tube via a transmission rod, and connects the pressure receiving plate with a side of the strain tube. The peripheral portion is connected via a circular plate having elasticity and low rigidity, and the other end of the strain-generating tube is connected to the bottom of a bottomed cylindrical case having a highly rigid mounting flange, and the pressure receiving The pressure receiving plate and the strain cylinder are housed in the bottomed cylindrical case via watertight means with the pressure receiving surface of the plate exposed, and the vertical load applied to the pressure plate is transferred to the strain generating tube through the transmission rod. The strain is transmitted to the diaphragm of the cylinder, and the amount of strain generated in the diaphragm is converted into an electrical output by a strain gauge attached to the diaphragm and extracted.

In addition, as a measuring device for horizontal stress on a wall surface, for example, as disclosed in JP-A-51-124481, it consists of an outer box and an inner box placed inside the outer box. It can move freely in the direction parallel to the friction surface with respect to the outer box, and is supported by a ball bush or chain so that movement in the direction perpendicular to the friction surface is restricted, and the inner box can move. A friction force measuring device has been proposed in which an inner box is provided with a load cell that directly detects the frictional force, and an outer box is provided with a bearing screw that contacts the load cell and resists the frictional force together with the load cell.

However, these conventional soil 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 section are integrated into a detection block, and the detection section is formed into a thin plate shape that is easily deflected in the friction direction.
A friction force meter has been proposed in which a strain gauge is glued to the thin plate-like part, 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, Vol. 44). No. 381
(See 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 these problems, the structure is complicated and machining is difficult, so only small-sized products can be obtained.
m ² ) is impossible to apply to large wall stress meters due to machining and assembly work.

The present invention has been developed in view of the above circumstances, and has a simple configuration that allows for a relatively low-cost increase in size, and also allows the vertical stress generated in the retaining wall and the horizontal stress in a specific direction to be reduced without interfering with each other. The object of the present invention is to provide a large-sized wall stress meter that can detect the stress at the same time and with high precision.

In order to achieve the above object, the present invention provides a large-scale wall stress meter for measuring the vertical stress and horizontal stress occurring on the wall surface of a retaining wall. A plurality of two-component beam-type load cells each having a strain gauge for detecting shear force attached to the surface, and a material with a friction coefficient approximately the same as that of the retaining wall attached to the pressure receiving surface to provide high rigidity. a pressure-receiving plate, a box-shaped body housing the load cell and the pressure-receiving plate therein, and having a large rigidity and being embedded and fixed in the retaining wall; and sealing a gap that occurs between the pressure-receiving plate and the main body. and a packing having flexibility, each of the load cells is arranged such that one of the two surfaces to which the strain gauge is attached and the longitudinal axis of the beam are parallel to and the same as the pressure receiving plate. The load cells are arranged so as to face the same direction, and one end of each of the load cells is firmly connected to the pressure receiving plate, and the other end is firmly connected to the main body, respectively, so that the vertical stress generated in the vertical direction of the wall surface of the retaining wall and the retaining wall The horizontal stress generated in a direction parallel to the plane of the load cell and perpendicular to the vertical axis of the beam of the load cell can be detected simultaneously without interference with each other.

Hereinafter, the present invention will be explained 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, and FIG.
3 is a perspective view showing the structure of an embodiment of a two-component beam type load cell which is one component of the present invention.

In the case of the embodiment shown in FIGS. 1 and 2, there are roughly four two-component beam type load cells (hereinafter simply referred to as load cells) 1, a pressure receiving plate 2, and a main body 3.
and a packing 4 for sealing. Here, the load cell 1 is a beam with a square cross section (sometimes rectangular) as shown in Figure 3.
Holes 1b and 1c of equal depth are bored in the middle part of 1a in the vertical direction (perpendicular to the pressure receiving plate 2, which will be described later) from the upper and lower surfaces, and strain gauges SG1 and 1c are formed in the bottoms of the holes 1b and 1c, respectively. SG2
And SG3 and SG4 are attached by adhesive or other means. Strain gauges SG1, SG2, SG3
and SG4 are ± with respect to the longitudinal axis of beam 1a.
It is attached in a 45° direction. In addition, in the middle part of the beam 1a, which is slightly away from the holes 1b and 1c,
Holes 1d and 1e of equal depth are drilled in the left and right directions (horizontal to the pressure plate) from the left and right sides, and strain gauges SG5, SG6, SG7, and SG8 are attached to the beams at the bottoms of the holes 1d and 1e, respectively. It is attached in a direction forming an angle of ±45° with respect to the longitudinal axis of 1a. Then, the lower surface of one end side of the beam 1a is slightly protruded to connect the connecting portion 1f to the main body 3, which will be described later.
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 chrome 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 reinforcing ribs (not shown) provided on the steel plate to increase rigidity, and has a concave portion on the pressure receiving surface 2a side. 2b is formed, and in this concave portion 2b,
Attach a retaining wall material, especially a material with an equal friction coefficient. In this embodiment, concrete 5 is placed in the recessed portion 2b.

The main body 3 has a box shape with one end opened so that the load cell 1 and the pressure receiving plate 2 can be housed therein, and the pressure receiving plate 2 can be fitted into the opening with a predetermined gap. load cell mounting portions 3b, 3c, 3 provided at four locations on the bottom portion 3a.
d and 3e, the connecting portion 1f of the beam 1a is firmly secured by bolting or welding with the vertical axis of the beam 1a of the load cell 1 being parallel to and facing the same direction as the pressure receiving plate 2. connected. The same material as that attached to the surface of the pressure receiving plate 2, in this case concrete 6, is also placed on the surface side of the main body 3, and these concretes 5 and 6 are formed on the same plane.

The packing 4 for sealing 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, and is made of a flexible material such as rubber and straddles the gap 7. One side is fixed to the peripheral edge of the pressure receiving plate 2 with a packing press plate 8, and the other side is fixed to the main body 3 with a packing press plate 9. Note that 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 is embedded in a concrete retaining wall 10 such that the surface of the pressure receiving plate 2 and the surface of the main body 3 are flush with the pressure receiving surface 10a of the concrete retaining wall 10. Although FIG. 4 shows an example in which one wall stress meter is installed, it is also possible to install a plurality of wall stress meters vertically in a column, or to install one in a column on the bottom pressure receiving surface 10b of the concrete retaining wall 10. Multiple units may be installed.

Next, the operation of the embodiment having such a configuration will be explained. On the pressure receiving surface 10a side of the retaining wall 10,
It is assumed that earth and sand have been deposited. Now, when the accumulated earth and sand 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, It is bent in the y direction shown in the third figure. Then, strain gauges SG5 to SG8 attached to the bottom surfaces of the holes 1d and 1e, 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 the strain gauges are proportional to the applied force. Outputs electrical signals. At the same time, the beam 1
Since a is bent in the x direction in Fig. 3,
Holes 1b and 1c are horizontal surfaces with respect to the pressure receiving plate 2
Strain gauges SG1 to SG4 attached to the bottom of the beam 1a detect the shear strain in the component in the direction perpendicular to the length of the beam 1a and horizontal to the pressure plate 2, and generate electricity proportional to the frictional force acting on the pressure plate 2. Output a signal. 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. Four strain gauges SG5 to SG8 for detection and four strain gauges SG1 to SG4 for horizontal shear strain detection are attached, each forming a well-known Wheatstone bridge circuit. They are configured to be connected in parallel to obtain vertical and horizontal shear strains. Therefore, according to this embodiment, even if, for example, 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.
Since shear strain is detected, there is an advantage that the output strain does not change depending on the length of the load cell 1 in the axial direction. The strain gauge that detects shear strain in the vertical and horizontal directions is connected to the beam 1 of the load cell 1.
Since they are attached to the mutually orthogonal surfaces of the beam 1a, the vertical stress on the pressure receiving plate 2 and the horizontal stress perpendicular to the longitudinal axis direction of the beam 1a and parallel to the pressure receiving plate 2 increase or decrease, respectively. High precision measurement is possible without mutual interference. By the way,
In this example, the interference could be suppressed to within 0.5%.

Further, according to the above embodiment, since the concave portion 2b is formed on the pressure receiving surface 2a side of the pressure receiving plate 2, this concave portion is filled with a material (concrete, mortar, etc.) having the same coefficient of friction as the retaining wall surface 10. 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 3, etc. It is sufficient to attach a material with approximately the same coefficient of friction as .

Further, although an example in which four load cells are used has been described, three or five or more load cells may be used.

In addition, the sealing packing 4 is not limited to a plate-shaped one, and may include a deformable absorbing layer made of a rubber compound (for example, chloroprene rubber with sealed bubbles) that does not restrict the movement of the pressure receiving plate 2 and the main body 3.
It may be provided between (gap 7).

As described in detail above, the present invention has a simple structure that is easy to process and assemble, so it is possible to increase the size at a relatively low cost, and to reduce the vertical stress generated in the direction perpendicular to the retaining wall surface. It is possible to provide a large-sized wall stress meter that can simultaneously detect horizontal stress occurring in a direction parallel to a wall surface and perpendicular to the longitudinal axis of a beam of a load cell without interfering with each other and with high precision.

[Brief explanation of 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. 1, and FIG. 3 is a component of the present invention. FIG. 4 is a perspective view showing the configuration of an embodiment of a two-component beam type load cell, and FIG. 4 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, 1f, 1g... Connecting portion, 2... Pressure receiving plate, 2a... Concave portion, 3... Main body, 3b to 3e... ... Two-component beam type load cell mounting part, 4 ... Packing, 5, 6 ... Concrete, 7 ... Gap, 10 ... Concrete retaining wall.

Claims (1)

[Claims] 1. In a large wall stress meter for measuring vertical stress and horizontal stress on the retaining wall surface, strain gauges for shear force detection are attached to two surfaces parallel to the longitudinal axis of the beam and perpendicular to each other. a plurality of two-component beam-type load cells formed by a plurality of load cells; a highly rigid pressure receiving plate having a pressure receiving surface attached with a material having a friction coefficient substantially the same as that of the retaining wall; and the load cells and the pressure receiving plate. The main body has a box shape and is embedded and fixed in the retaining wall, and has a flexible packing that seals a gap between the pressure receiving plate and the main body. The load cells are arranged so that one of the two surfaces to which the strain gauges are attached and the longitudinal axis of the beam are parallel to the pressure receiving plate and face the same direction, and each of the load cells is One end is firmly connected to the pressure receiving plate and the other end is firmly connected to the main body. A large wall stress meter characterized in that it is configured to be able to simultaneously detect horizontal stress occurring in a direction orthogonal to the vertical axis of the beam without mutual interference.