JPS60190828A - Detector for measuring two-component earth pressure and pore water pressure - Google Patents

Abstract

PURPOSE:To make it possible to measure axial tension, shearing force and pore water pressure in the earth by one detector, by providing one load cell, which can measure the two-component forces, in one cabinet, and providing pore water pressure gages in a cabinet lid. CONSTITUTION:A detector is provided with a two-component load cell 6, which can detect the displacements of axial tension and shearing force, between a cabinet lid 3 and a bottom wall 5 of a cabinet 1. Pore water pressure gages 7 are provided in the cabinet lid 3. By using one detector, the axial tension and the shearing force are detected by the load cell. The pore water pressure at a measuring part can be measured by the pore water pressure gages provided in the detector. Therefore, the secondary stress state in the earth can be evaluated only by burying one detector in the earth. The burying work of a main body and cable can be simplified.

Description

[Detailed Description of the Invention] The present invention relates to a detector, and an object of the present invention is to provide a detector that can easily and highly accurately detect and evaluate the two-dimensional stress state of 4.
Let's use pestle 1.

Evaluation of the internal stress of the filter membrane (see Figure 1)
It is necessary to measure earth pressure and pore water pressure in order to evaluate the stress of
or m1 pore water pressure part 4 can be used as a single device by buttoning them together, or one-way 1. Month. ．． , l are only used. However, in order to evaluate the +5 force state of H structures, iTo boards, etc., it is necessary to evaluate not only the total stress but also the increased stress. For this reason, pore water pressure gauges were installed when installing earth pressure gauges, and each had a conductive wire for output, which caused the problem of requiring a great deal of labor to process the large number of conductive wires. . In other words, conventionally, as shown in Fig. 2, a 14-type + pressure gauge was used, such as a 3-sided soil pressure meter to evaluate the two-dimensional stress state, or a 7-sided soil pressure gauge to evaluate the three-dimensional stress state. Measurement is carried out using a combination of 3 or 7 a), and in addition to this, a pore water pressure gauge (
b) In order to evaluate the stress state at one point when installing 4
Conductive pair or eight pairs! ! (c) must be addressed. In addition, when analyzing two-dimensional stress states, if the set angle of a single-type soil pressure meter changes over time, the analytical value will be inaccurate because the set angle of the second soil pressure gauge is not measured. As a countermeasure, if we could take a soil pressure gauge to the open frame (d),
Due to the opening of the frame, there is not only the problem that the stress state of G is disturbed, but also a large number of installations are required, which incurs a great deal of economic cost. One load cell capable of measuring two-component forces is installed in one housing, a pore water pressure gauge is attached to the lid of the housing, and one conductive wire bundle cable is led out from the housing. This system enables the measurement of axial force, shear force, and 17 tl pore water pressure in the soil with a single detector, and there is almost no disturbance in the central force field.
It can approximate the stiffness of soil and improves the reliability of soil stress evaluation.

Hereinafter, embodiments of the present invention will be explained based on the facts.
3 to 6 show a first embodiment.

(1) is a thin cylindrical rigid housing with a bottom;
There is a gap of 0.5 to 1 between the side wall (2) and the periphery on the opening surface of 1).
．． The detection lid (3) with a gap of 0 mm is supported by a sealing material (4) made of raw rubber or the like which has a small change over time, is watertight, and has a low elasticity shell.
) and the bottom wall (5) of the casing (1) to detect the displacement of axial force (arrow A) and shear force (arrow B) + 1 unit. I'll wear it. Also (7
) is the pore water pressure A1 provided in 1(3) for detection in 1-, and a strain gauge (9) is pasted 1 m back on the inner end of the through hole (8'I) drilled in the detection lid (3). The outer periphery of the distorted plate (10) made of twisted bronze is airtightly fixed, a porous metal (11) is provided at the outer end of the through hole (8), and a protective porous retaining plate (12) is provided on the outer surface of the porous metal (11). It is fixed to form a pressure receiving chamber (13).

(14) is a conductive wire bundle cable for supplying power to the two-component load cell (6) mentioned above and the strain gauge (8) for pore water use (7), and for deriving the output; The circuit diagram is shown when 2I has one l1il gap pressure gauge (7).

B) An oil groove (15) is formed perpendicular to the detection direction.

1- When determining the two-dimensional stress state using the two-component top 1r and the pore water pressure measuring detector having the configuration described above, it is necessary to install it in the direction perpendicular to the open frame (D) as shown in Fig. 8. The two-dimensional stress state (σ8, σ,

τ□, τ, 8) and pore water pressure can be obtained, and at this time, the cable (14) has only two trees J! I! Not set.

Next, FIG. 9 shows another embodiment of the pore water pressure gauge (7a), in which an O-ring (16
) such that the back pressure 81-1 covers the strain plate (10) through the
1-A box (17) is installed airtight and a strain gauge (9
) The cable (14a) led out from the cable (14a) is also sealed with revorank cement (18), so that no back pressure is applied to the strain plate (10). In this case, the seal 4 of the above embodiment
It is better to leave A (4) in place to prevent l +

As described above, according to the present invention, the row 1 cell detects the 1 hIi force and the front shear force using one detector, and the pore water pressure AI provided on the detection lid detects the Since it is possible to measure 31 pore water pressure, it is possible to evaluate the two-dimensional force state in the soil by simply burying two detectors in the soil. This invention has the following characteristics: it is easy to operate, and 1ll11 constants can be obtained with high precision; therefore, the effects of this invention are extremely large.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the state of measuring the dimensional stress of the filter membrane, Fig. 2 is an explanatory diagram showing the conventional measuring method, Fig. 3 is an explanatory diagram showing an embodiment of the device of the present invention. Figures 5 and 6 are sectional views taken along the line TV-IV and V-
7 is a circuit diagram of the same device, FIG. 75B is an explanatory diagram showing the two-dimensional stress measurement state of the device 6, and FIG. FIG. 4 is an enlarged cross-sectional view of four parts of another embodiment of the present invention. (1) Housing (3) Detection lid (8) Two-component load cell (7) Pore water pressure gauge (14) Cable (15) Above the wave groove” District Law Figure 7

Claims (1)

[Claims] A detection lid is provided at the opening of the housing so as to have a predetermined degree of freedom with the side wall of the housing, and a component loading cell is interposed and fixed between the detection lid and the housing. Part 1)
11 Water pressure tears! Looking down, the sensor is characterized by forming wave grooves perpendicular to the shear stress detection direction of the component load cell on the surface of the detection lid, and from the housing, each of the above-mentioned detection conductors is led out by a cable. A detector for measuring two-component soil pressure and pore water pressure.