JPH0534252A - Shearing tester for ring of both constant volume and constant pressure - Google Patents

Abstract

PURPOSE:To correctly measure residual strength exhibited on a slide fade by reproducing landslide and slide of slope failure with a simple structure. CONSTITUTION:A lift 15 which is vertically moved by a jack 18 is mounted on two support pillars 2,2 supported by a base 1 and an upper end plate 33, while a shearing shaft 7 which is rotated by a servo motor 14 is pivoted on the lift 15 via a torque meter 8. A movable plate 25 which can be positioned at optional positions of the pillars 2, 2 above the lift 15, while a lower sample container and an upper sample vessel are placed in a water tank 20 attached to the shearing shaft 7 and on an opposite face with the movable plate 25, respectively. Then upper ends of pressure applying levers 28, 28 exhibited in the upper sample vessel through the movable plate 25 are connected to an output end of a load mount part B placed on the upper end plate 33 via an appropriate load cell 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ring shear tester for both constant volume and constant pressure for measuring the residual strength which is important when performing embankment or cutting on unstable ground.

[0002]

2. Description of the Related Art Residual strength is the strength exerted when rearrangement of clay particles occurs along the shear plane, so the measurement can be performed with large displacement shear incorporating a rotary shearing mechanism. A ring shear tester is used. However, in the structure of the conventional testing machine, there are serious problems related to the accuracy of the experimental results due to the blurring phenomenon of the rotating disk caused by the loading mechanism and the shearing mechanism and the complexity of the operation. Also,
Residual strength is the strength that appears over a long period of time, and since it needs to be sheared under drainage conditions, the conventional constant pressure type ring shear tester requires a long time to measure the residual strength, and it is necessary to perform emergency measures from the site. I cannot respond to requests.

[0003]

Therefore, according to the present invention, when the shear load is placed on the sample, not only the rotating disk is shaken but the reliability of the experimental result cannot be improved.
There are drawbacks such as complicated operation and long time required for residual strength measurement. The present invention aims to solve the above-mentioned problems.

[0004]

In the ring shear tester for both constant volume and constant pressure of the present invention, in order to solve the blur phenomenon of the rotating disk and the complexity of the operation, the shear plane of the specimen in the upper and lower containers of the ring is solved. Has a structure in which it rotates in parallel completely (shear shaft, rotating plate, and platform integrated structure), and a simple mechanical structure with good operability. Moreover, the constant volume shearing function of this device can significantly reduce the test time.

[0005]

By loading the sample into the ring-shaped sample holding unit and then operating the load mounting section connected to the pressure ring, the pressure piece of the load mounting section is transferred to the pressure ring via the load cell. The sample stored in the ring-shaped sample holder is pressurized while pressure is applied and the load at that time is detected by the load cell. Then, when the servomotor of the torque mounting portion is rotated in a predetermined direction, the rotational movement is transmitted to the shear shaft via the torque meter. Then, the ring-shaped lower container installed on the shearing shaft is rotated, and at that time, a shearing force is applied to the combined portion of the lower container and the upper container of the sample contained in the ring-shaped upper and lower containers. Then, the rotational shearing force until the sample is sheared is detected by a torque meter, a constant pressure test is performed by feeding back the output of the load cell to the control system of the load mounting section, and the displacement of the ring-shaped upper and lower containers is described above. Similarly, a constant volume test is performed by feeding back to the control system of the load mounting section.

[0006]

EXAMPLES The present invention will be described in detail below. The constitution is roughly divided into a sample holding section A for holding a sample (soil collected from the site to be measured), and the holding section A.
The load carrying section B for applying a pressure to the sample held in 1. and the torque carrying section C for applying a shear torque to the sample.

For the sake of structural convenience, the torque mounting portion C will be described below. From the torque mounting portion C, a pair of columns 2, 2 are erected on the left and right on the base plate 1, and the upper portion is connected and fixed by the upper end plate 33. Then, the lift base 1 is composed of the upper support plate 5 and the lower support plate 3 which are connected to the columns 2 and 2 by connecting rods 15 'and 15'.
5, the upper and lower support plates 5 and 3 of the pedestal 15 and the columns 2,
Slide bearings 4, 4, 4 ', 4'with 2 respectively
It is freely slidable vertically via the support plate 3, and the torque input shaft 9 of the torque meter 8 is passed through the center of the lower support plate 3 in the downward direction and is rotated with the support plate 3 via a bearing. It is free, and the gear 10 is fitted to the lower end of the input shaft 9. Then, the servo motor 14 is attached to the side surface of the support plate 11 projecting downward toward one end of the lower support plate 3, and the lower surface of the support plate 3 is connected via the clutch 13 mounted on the output shaft of the servo motor 14. A gear 12 rotatably provided therebetween is meshed with the gear 10 so that the rotation of the servomotor 14 is transmitted to the gear 10. Further, a pressure plate 17 of a jack 18 is connected to a lower surface of the support plate 3 and , The pressure plate 1
The small gear 16 of the tachometer S ₃ mounted on the
I am biting.

A bearing box 6 is attached to the central portion of the upper support plate 5, and a shear shaft 7 is rotatably supported via upper and lower bearings supported in the box 6, and the lower end of the shaft 7 is supported. Is fitted to the output shaft end of a torque meter 8 pivotally supported in the center of the lower support plate 3, and the output shaft of the torque meter 8 and the shear shaft 7 are fixed so as to rotate integrally. ing.

Next, the sample holder A is composed of the two columns 2, 2.
A movable plate 25 supported above via clamp bushes 26, 26 which can be fixed at an arbitrary position by supplying fluid pressure, and an upper collar-shaped portion 7'of the shear shaft 7.
Composed between and. That is, the bottom plate 19 of the annular water tank 20 is fixedly installed concentrically with the shear shaft 7 on the collar-shaped portion 7 ′ formed on the top of the shear shaft 7, and the shear shaft 7 extending through the center of the bottom plate 19 is directed upward. the projecting shaft portion 7 ", from the lower inner ring 21 ₁ and the inner race 21 ₁ circumscribes the lower pressure radial crushing 23 and article thickness adjustment via a spacer 23 'of the lower outer ring 21 ₂ which held concentrically on the outside The lower material container 21 is fitted into the inner ring 21 ₁ and the outer ring 21 ₂ and the upper portion of the protruding shaft portion 7 ″ is fitted into the upper portion of the protruding shaft portion 7 ″ through a bearing, and the lower surface of the movable plate 25 is screwed into the screw rod 29. Upper material container 22 composed of an upper inner ring 22 ₁ screwed onto the inner ring 22 ₁ and an upper outer ring 22 ₂ held outside the inner ring 22 ₁ via an upper pressure ring 24.
Are brought into contact with each other to hold the sampled material a in the cavity formed by the upper and lower sample holders. Then, the lower ends of the pressure rods 28, 28 slidably held through the slide bearings 27, 27 attached to the movable plate 25 are brought into contact with the upper side of the upper pressure ring 24 so that the pressure rods 28 The upper ends of the and 28 are respectively screwed to the lower surface of the pressure plate 30. Further, a hanging rod 43 is provided on the lower surface of the movable plate 25 toward the upper support plate 5, and the hanging rod 4 is provided.
A gap sensor S ₁ facing the gap piece 5 ′ on the support plate 5 is attached to the lower surface of 3.

Next, the load carrying portion B will be described. On the upper end plate 33, the bellows 3 are provided between the mounting base plate 34 and the body portion 35 and between the body portion 35 and the upper lid 36.
A guide rod 40 is provided which sandwiches the outer peripheral portions of 8 and 39 and projects downward in the center portion of the upper lid 36 in the body portion 35.
Thus, the piston 37 is held freely movable up and down. The upper and lower end steps of the piston 37 are watertightly held between the bellows 38, 39 and the piston 37, respectively, and the central lower end of the piston 37 and the mounting base plate 3 are held.
By mounting the bellows 41 over the bridge 4, the bellows 41 and 38 form a lower pressurizing chamber 34 ', and the bellows 39 and the upper lid 36 form an upper pressurizing chamber 36', respectively. A load cell 32 is interposed between a lower end of a pressure piece 42 screwed and projected at a downward end of a central portion and a ball 31 on the pressure plate 30, and is erected on the support plate 5 (not shown). The displacement gauge S ₂ for measuring the displacement between the protrusion 30 ′ protruding laterally from the pressure plate 30 is attached to the upper end of the column.

Next, the series of operations of the present invention will be described in detail. First, in order to store the sample a sampled on site between the upper and lower pressurizing rings 23 and 24 of the sample holder A, the bellows of the load mounting unit B is first stored. After removing the fluid pressure being supplied into the ramshi cylinder, loosen the holding screw 2'at the upper end of one of the columns 2 and then rotate the upper end plate 33 in the horizontal direction with the upper end of the other column as the base point to load the load. The frame B is once moved laterally from the portion of the pressure piece 42 to fully open the upper part of the sample holder A, and then the clamp bush 26
When the clamp 18 is loosened and the jack 18 is operated to raise the elevating frame 15, the sample holder A
When the upper inner ring 22 ₁ and the outer ring 22 ₂ reach a space enough to be separated sufficiently upward from the annular water tank 20, the clamp bushes 26, 26 are supplied with pressurized fluid to supply the pressurized fluid to the bushes 26. , 26 are held stationary on the columns 2, 2. Then, this time, the jack 18 is operated to lower the elevating / lowering platform 15 and stop when returning to the approximately previous position, so that the lower ends of the upper inner ring 22 ₁ and the outer ring 22 ₂ and the upper end of the annular water tank 20 are stopped. It is possible to secure a sufficient working space (the space required for the sample loading work) between the two. Therefore, the sample a formed in a donut shape in advance is set, and water is put in the water tank 20 so that the water is above the upper surface of the sample.
The sample loading operation is completed by bringing the end facing the lower sample container 21 into contact. Therefore, at this point, the aquarium 20
The water in the inside penetrates into the sample a through water passage holes (not shown) formed in the upper outer ring 22 ₂ and the lower outer ring 21 ₂ , respectively,
The sample a is in a water-containing state. To test the loaded sample a, there are two cases: a case where a shear load is applied while keeping a constant pressure, and a case where a shear load is applied while keeping a constant volume.

First, the case of conducting a constant pressure test will be described. The position adjustment of the gap sensor S ₁ and the zero point adjustment of the vertical displacement meter S ₂ , the rotational displacement meter S _{3 and the} like, and the setting of the planned load value etc. are made to the initial state. This completes all preparations for the test. Then, by pressing the start button of the control system, high-pressure air is sent into the upper pressurizing chamber 36 'of the load mounting part B from the air supply port b, the piston 37 is pressed down, and the pressurizing piece 42 is pressed. Via the load cell 32, the ball 31, and the pressure plate 30.
The upper pressure ring 24 is pressed by the lower end of the sample, and the set pressure is applied to the sample a interposed between the pressure ring 24 and the lower pressure ring 23. Then, next, the servomotor 14 is rotated to rotate the input shaft 9 via the clutch 13, the gears 12 and 10, and thereby the rotational operation is transmitted to the shear shaft 7 via the torque meter 8. And the water tank 2 attached to the upper part of the shear shaft 7
The lower sample container 21 in 0 is rotated. At this time, a shear stress acts between the part held in the upper sample container 22 and the part held in the lower container 21, and the magnitude of the stress is detected by the torque meter 8 at that time. The change of the vertical load acting on the sample due to the change of the state is detected by the load cell 32, and the detected value is fed back to the pressure control system of the load mounting section B. That is, when a pressure change acting on the sample a is generated, for example, when it becomes higher than a set value, the pressure acting on the piston 37 is reduced by switching the passage of the air servo valve d from the air supply port b to the direction c. Then, the pressure is returned to the set value, and when it is low, the passage of the air servo valve d is switched to the air supply port b to return the pressure to the set value. In this way, the detected load is fed back to the control system of the load-carrying part B, and a constant pressure set in advance is always applied, while the relation between the shear stress and the rotational displacement (rotation angle) or the relation between the shear stress and the vertical load is applied. Others can be quantitatively obtained.

The constant volume test is carried out by feeding back the detection value of the gap sensor S ₁ to the pressure control system of the load carrying section B. Further, the initial conditions of each part of the control system are the same as those in the case of the above-mentioned equal pressure test, and the description thereof is omitted to avoid duplication. First, when the shear shaft 7 is rotated by the rotation of the servomotor 14 via the torque meter 8, the sample a If the volume changes due to a change in the state of soil particles during operation, for example, if the volume changes above a preset value, the servo valve d is opened to the air supply port b side and the piston 37 Press to operate to reach the set volume, and when the volume falls below the set value by placing a shear load, the servo valve d is opened to the air supply port c side, and the pressure acting on the sample Quantitatively about the relationship between shear stress and vertical load, the relationship between shear stress and rotational displacement, etc., as in the case of the constant pressure test, while keeping the sample volume constant by reducing the value to a predetermined volume. To measure Can.

[0014]

Although a constant-pressure ring shear tester has been conventionally used for residual strength measurement, the test requires a long period of time and thus cannot immediately respond to an urgent request from a disaster site. Since the sheared surface is formed in a ring shape, rapid and continuous residual strength measurement is possible. Further, the shear shaft and the torque mounting portion for driving the shear shaft are arranged in the lower portion with the sample holding portion interposed therebetween, and the load mounting portion is provided in the upper portion so that the configuration can be simplified and the operation is stabilized. Also, constant pressure can be easily measured by feeding back the vertical load to the load mounting portion, and similarly, by feeding back the vertical displacement to the load mounting portion, constant volume measurement becomes possible and the range of use can be remarkably expanded. The data obtained in this way facilitated landslide and slope risk assessment, design for embankment and cutting work, and elucidation of basic mechanical properties of soil.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view of a ring shear test device for both constant volume and constant pressure.

FIG. 2 is an enlarged vertical side view of the main part of the same.

[Explanation of symbols]

1 plate 2 props 7 shear axis 8 Torque meter 14 Servo motor 15 Lifting platform 18 jacks 20 aquarium 21 Lower container 22 Upper container 25 movable plate 28 Pressure rod 33 Top plate A sample holder B load platform C torque mounting section

Claims (3)

[Claims] 1. A sample holder is constituted by an upper container composed of an inner ring and an outer ring, and a lower container composed of an inner ring and an outer ring,
The lower container of the sample holder is fixed in a water tank, the upper container is fixedly held by a position adjusting movable plate, and a pressure ring interposed between an inner ring and an outer ring of the upper container is loaded and loaded via a load cell. It is connected to the pressure shaft of the upper part, and the water tank is connected to the torque mounting part via a torque meter so that the vertical load is mounted on the upper container and the shear torque is mounted on the lower container. Ring shear tester for both constant volume and constant pressure. 2. The constant pressure shear test is performed by feeding back the vertical load detected from the load cell to the control system of the load mounting section.
The constant pressure ring shear test device described. 3. A constant volume ring shear test apparatus, wherein a constant volume shear test is performed by feeding back the vertical displacement to a control system of a load mounting section.