JPH1137914A - Shear force measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shear force measuring instrument that can experimentally obtain external force to a buried pipe in soil by a simple method, when the amount of shear displacement and shear speed are large. SOLUTION: In a measuring instrument 2, a slide table 34 is placed at a rail part 32 being fixed onto a pedestal part 40 so that it can be moved, and a driving mechanism 50 is connected to the slide table. Furthermore, a polyethylene plate 10 is fixed onto the slide table, a ring 4 accommodating soil is placed on the upper surface, a load cell 6 for measuring pressure being applied to the ring is mounted. Then, by actuating a driving device, the slide table 34 is pulled by a wire 52 and is moved, and the polyethylene plate 10 is moved while touching the soil. Shear force being generated by the movement of the polyethylene plate is measured by the load cell or the movement speed of the polyethylene plate is measured by a distance meter 20. In this manner, the shear force between the polyethylene plate 10 and the soil can be measured based on experiment conditions, for example, of the movement distance of approximately 120 mm and the maximum movement speed of approximately 160 cm/sec.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shear force measuring device for measuring a shear force generated between soil and an object to be inspected,
In particular, the present invention relates to a shear force measuring device capable of experimentally measuring a shear force applied to a pipe buried in the ground assumed when a large earthquake occurs, for example, when a relative speed between the two is high and a moving amount is large.

[0002]

2. Description of the Related Art In order to ensure the safety of gas pipes buried underground, the external force acting on the buried pipe by the ground during an earthquake is quantitatively grasped, and the behavior of the buried pipe at that time is confirmed. Is becoming important. One element to know that,
There is a shearing force of the soil around the buried pipe. By determining the shearing force of the soil, the deformation of the soil that occurs when an earthquake occurs,
That is, it is considered that the external force applied to the pipe can be calculated in advance, and sufficient seismic resistance can be given to an anticipated earthquake by designing and burying the pipe that can withstand the external force.

[0003] Conventionally, in order to test the shearing force of soil, FIG.
Was used as shown in FIG. The shear force measuring device 80 is mounted on a base 82, a container 84 movably disposed by rollers 83 and the like, a test container 85 divided into upper and lower parts of an upper box 86 and a lower box 87, and attached to the upper box 86. A test cell 85 is filled with dirt or the like to be inspected, and a container 84 is provided.
The lower box 87 of the test container 85 is fixed to the upper box 86, and a vertical force is applied to the upper box 86 from above, and the container 84 is gradually pressed from the side in the direction of the dynamometer 88. Then, since the lower box 87 of the test container 85 is fixed to the container 84, the lower box 87 moves together with the container 84, while the upper box 86 has a dynamometer 88 set on the side and the movement is locked. From the test container 85
A shear force in the left-right direction is generated in the soil accommodated in the container, and the shear force is measured by the dynamometer 88, and the shear resistance of the soil placed in the test container 85 is measured.

[0004]

However, the conventional shear force measuring device 80 cannot move the upper box 86 and the lower box 87 relatively to each other, and the shear displacement of the soil in the test is at most 10 mm. And the shear rate during the test was at most about 1 to 2 mm / min. Therefore, a test assuming a large earthquake, for example, when the shear distance exceeds 100 mm and the shear rate is 3000
It was not possible to experimentally determine the shear force of the soil under the condition of about 0 mm / min. In fact, it has been clarified from measurement records of earthquakes that such magnitudes of displacements and velocities have occurred in past large earthquakes such as the Great Hanshin-Awaji Earthquake, and the influence on buried pipes in such cases has been revealed. It was necessary to set criteria such as required safety.

[0005]

According to the present invention, a shear force measuring device is constructed as follows in order to determine the interaction between a ground and a pipe in a situation where a shear rate and a shear distance correspond to an actual large earthquake. did. That is, a movable base that movably supports the movable part in the horizontal direction, a movable part for attaching the first inspection object that is a coating on the pipe surface, and the soil that is the second inspection object is stored, and the first inspection object is stored on the first inspection object. A frame for bringing the soil into contact, a pressurizing means for pressing the soil stored in the frame from above, a moving means for moving the movable part on the moving table at a predetermined speed, and measuring a force generated in the frame. A shear force measuring device was constituted by the force measuring means and the distance measuring means for measuring the moving distance of the movable part.

[0006] As the moving table, it is preferable to use a sliding table such as a metal slide table which has a small friction and has a small vertical movement of the movable part when moving. The type of the first inspection object is not limited, such as metal, synthetic resin, wood, and soil. The frame accommodates the soil to be the second inspection object and makes direct contact with the first inspection object, and is preferably held so as not to make direct contact between the first inspection object and the frame. The pressurizing means presses the first test object against the second test object at a predetermined pressure, and is not limited to a weight but may be a spring, a hydraulic pressure, a pneumatic mechanism, or the like.
In the case of a weight, it may be placed directly on the top, or may be of a hanging type. The moving means for moving the movable portion on the moving table includes a tension device using a weight, a piston cylinder mechanism using a pneumatic or hydraulic device, a motor mechanism, a spring mechanism, or a combination of these as appropriate.

[0007] According to this shear force measuring instrument, soil to be inspected is put into the frame, and the soil is brought into contact with the first object to be inspected.
The movable part to which the first inspection object is fixed is moved at a predetermined speed. Thereby, the force generated in the frame is measured by the dynamometer, and the shear force generated between the first test object and the second test object when both the shear distance and the shear rate are large can be accurately measured.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a shear force measuring device according to the present invention will be described with reference to the drawings.

FIG. 1 shows the entire measuring instrument 2. Measuring instrument 2
Is a pedestal portion 40, a rail portion 32 fixed on the pedestal portion 40, a slide table 34 movably provided on the rail portion 32, and a drive mechanism for moving the slide table 34 in the lower left direction in the figure. 50 and slide table 3
The ring 4 includes a ring 4 provided on the ring 4, a load cell 6 connected to the ring 4, and a pressing mechanism 8 for pressing the soil contained in the ring 4 from above.

The pedestal portion 40 is a pedestal made of a metal frame, and is firmly assembled as a whole. Rail part 32
Is a rail for supporting the slide table 34 smoothly and movably in the horizontal direction with small resistance. On the upper surface of the slide table 34, the polyethylene plate 10 to be first inspected is fixed.
The wire 52 connected to the piston 54 of the drive mechanism 50 is attached to the side of the drive mechanism 50.

As shown in FIG. 3, the driving mechanism 50 includes a piston 54 and a cylinder 56 in which the piston 54 is airtightly housed.
And a pressure reducing pump 58 and an air tank 60 connected to the cylinder 56, an adjusting valve 62 for adjusting the pressure reducing speed of the air in the cylinder 56, and an air opening / closing valve 64. The piston 54 may have its own weight and function as a weight.

As shown in FIG. 2, the pressing mechanism 8 has an upper arm 22 and a lower arm 24 connected in parallel by bolts 26, and extends downward from the center of the upper arm 22. Column 28 rests on the lid 12 to be described later, and the lower arm 24
The weight 30 is hung down at the center. Further, the upper arm 2
A stylus of the dial gauge 16 for measuring the vertical movement of the arm 22 is in contact with the upper surface of the second arm 2.

The ring 4 has a diameter of about 100 mm and a height of about 3
A metal ring having a diameter of about 0 mm and a width of about 10 mm is provided with a lid 12 having substantially the same inner diameter. The load cell 6
It is a measuring instrument for measuring the load applied in the longitudinal direction.
One end is fixed to a gate-shaped support member 14 fixed to zero, and the other end is connected to the ring 6 via a joint 7. A reflection plate 18 is attached to the right end of the slide table 34 so that the laser beam from the laser type distance meter 20 installed on the pedestal portion 40 is reflected to a light receiving section (not shown) of the distance meter 20. It has become.

Next, a method of measuring the shearing force by the measuring instrument 2 will be described.

First, the polyethylene plate 10 to be inspected is fixed to the upper surface of the slide table 34 with screws or the like. Next, the piston 54 is lifted in the cylinder 56,
When the height is set to an appropriate value, the on-off valve 64 is closed, and the wire 52 is connected to the slide table 34 so that the piston 54 does not drop. Further, the pressure reducing pump 58 is operated to maintain the inside of the tank 60 at a predetermined pressure, and the adjusting valve 62 is adjusted so that the pressure reducing speed in the cylinder 56 is reduced.
That is, the falling speed of the piston 54 is set.

Next, the earth to be inspected is stored in the ring 4. The soil is set to the specified water content, and the ring 4
Insert so that the density inside becomes uniform, and squeeze it sufficiently.
This operation may be performed on the upper surface of the polyethylene plate 10 or at another place, and the ring 4 may be placed on the polyethylene plate 10. When placing the ring 4 on the polyethylene plate 10, a plate having a thickness of about 0.4 mm is interposed below the ring 4, and the soil is pressed against the polyethylene plate 10, and a predetermined space is provided between the ring 4 and the polyethylene plate 10. Is formed. Then, the load cell 6 is connected to the ring 4, the lid 12 is placed on the upper surface of the soil, and the pressing mechanism 8 is placed on the lid 12.

Further, the user turns on the switch of the distance meter 20, irradiates the light receiving section with the laser beam applied to the reflecting plate 18, and sets the moving distance of the reflecting plate 18 so that it can be measured with time. Further, the dial gauge 16 is brought into contact with the upper surface of the arm portion 22 to measure the fluctuation of the ring 4 in the vertical direction.

When the measuring instrument 2 is set in this way, the on-off valve 65 is opened, and the pressure in the cylinder 56 is reduced. Then, the piston 54 falls at a high speed due to its own weight and the suction force of the cylinder 56, and is pulled by the wire 52, and the slide table 3 is pulled.
4 moves to the left, and the polyethylene plate 10 moves in contact with the soil. The shearing force generated by the relative movement is measured by the load cell 6, and the moving speed of the polyethylene plate 10, that is, the moving distance per time is measured by the distance meter 20. In this way, the shearing force between the polyethylene plate 10 and the soil is reduced by a moving distance of about 1
Measurement was possible under the experimental conditions of 20 mm and a maximum moving speed of about 160 cm / sec.

As described above, according to the measuring device 2, the shearing force test between the polyethylene plate 10 and the soil can be performed with the long moving distance secured and the moving speed conventionally obtained. Experiments can be performed reliably under high-speed conditions without any problems.

In the above example, the first object to be inspected was polyethylene, but the present invention is not limited to this.
Experiments with various materials such as wood and soil can be performed.
If both the first inspection target and the second inspection target are soil, it can be said that a shear force is generated at the boundary of the relative movement,
According to the present invention, the resistance of relative movement on the contact surface between different materials is determined as the shearing force.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A test of soil and a polyethylene material using a shear force measuring device will be described below.

The measuring instrument has a pedestal portion of about 100 cm in length and width, about 40 cm in width, and a cylinder having an inner diameter of about 20 cm and a height of 80 c.
m and the weight of the piston was 50 kg. The polyethylene plate had a width of 140 mm, a length of 300 mm, and a thickness of 10 mm. The polyethylene material coated on the surface of the gas pipe was peeled off from the gas pipe, extended to a flat surface, and fixed to a slide table. In addition, the surface of the polyethylene plate
Polished with No. 0 sandpaper. The sand used was mountain sand and had a compaction degree of 99% or more. The weight to press the sand is 16
kg.

FIG. 4 shows the test conditions. As shown in this table, the speed of the polyethylene plate was 1 to 160 cm / sec.
The shear force test with the soil was carried out by changing the above range, and the experimental result within the range of the experimental conditions which could not be set conventionally could be obtained reliably.

Some of the obtained results are shown in FIGS. FIG. 5 is a graph showing the relationship between the displacement of the polyethylene plate and the shearing force, and a displacement of 11 cm was obtained. FIG. 6 is a graph showing the relationship between the displacement of the polyethylene plate and the speed thereof, which was 160 cm / sec. It can be seen that the speed was obtained.

[0025]

According to the shear force measuring device of the present invention, the soil and the material to be inspected are brought into contact with each other at a predetermined pressure, and the two are moved with a desired relative speed and a sufficient moving distance while maintaining the state. So that it was not possible before,
A test can be performed to accurately measure the shearing force between an underground pipe and soil under fluctuations with large amplitude and high displacement speed, assuming a large earthquake.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an entire shear force measuring instrument according to the present invention.

FIG. 2 is a perspective view showing a part of a shear force measuring device according to the present invention.

FIG. 3 is a front view showing the entire shear force measuring instrument according to the present invention.

FIG. 4 is a table showing experimental conditions using a shear force measuring device according to the present invention.

FIG. 5 is a graph showing experimental results.

FIG. 6 is a graph showing experimental results.

FIG. 7 is a front view showing the entire conventional shear force measuring device.

[Explanation of symbols]

 2 Measuring instrument 4 Ring 6 Load cell 7 Joint 8 Pressure mechanism 10 Polyethylene plate 12 Lid 14 Support member 16 Dial gauge 18 Reflector 20 Distance meter 22, 24 Arm 26 Bolt 30 Weight 32 Rail 34 Slide table 50 Drive mechanism 52 Wire 54 Piston 56 Cylinder 58 Pressure reducing pump 60 Air tank 62 Adjusting valve 64 On-off valve

Claims (2)

[Claims] 1. A movable unit for mounting a first inspection object on an upper surface, a movable table supporting the movable unit in a horizontal direction so as to be movable, and a soil to be inspected as a second inspection object. A frame to be brought into contact with the first inspection object; a pressurizing unit that presses the soil stored in the frame from above; a moving unit that moves the movable unit along the moving table at a predetermined speed; A shear force measuring device comprising: force measuring means for measuring a force generated in the frame; and distance measuring means for measuring a moving distance of the movable portion in a timely manner. 2. The shear force measuring device according to claim 1, wherein the first test object is polyethylene.