JP3795721B2 - Small automatic repetitive one side shear test equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a small automatic repeated single surface shear test apparatus for obtaining a “shear force” which is a physical property value of a ground material used for stability analysis of a landslide.
[0002]
[Prior art]
In the soil test, a triaxial test, a ring shear test, a repeated one-side shear test, and the like are carried out as a shear test for obtaining a shearing force. Among them, the repeated one-surface shear test is a test for determining the shear strength of the ground material, and it is possible to test an undisturbed sample and is excellent in practicality because the test is simple. In this test, the shear box has a characteristic of relative displacement during shearing. Therefore, the shear box and the shear surface of the sample (specimen) are in contact with each other during shearing, and the obtained value is between the specimen shear planes to be obtained. The shear force (correction of peak strength and complete softening strength) and the resultant force of friction. Further, when the residual strength requiring a large displacement is obtained, the contact time between the shear box and the specimen is lengthened, so that the specimen is cut like a bonito by the edge effect of the shear box and is sandwiched between the shear box gaps. It has been pointed out that friction due to this sample leakage has an influence on the residual strength to be obtained.
[0003]
For this reason, conventionally, grease was applied to the shearing surface portion of the shearing box to reduce the friction between the shearing surfaces of the shear box and the specimen leaked from the clearance of the shearing box. However, this method can reduce friction but cannot completely remove it. In addition, since the friction reducing grease gradually peels off as the number of repeated shears increases, there is a problem that the friction reducing effect cannot be obtained gradually. In addition, the conventional vertical force loading is generally performed using a "weight" or "velopram cylinder (pneumatic)" stress control system, and the weight cannot be controlled during the test. There is a problem that skill is required for close contact between the specimen and the vertical load loading plate, and a compressor for generating air pressure is newly required.
[0004]
[Problems to be solved by the invention]
Therefore, the present invention incorporates a small high-rigidity load cell between the upper and lower shear boxes to measure the frictional force between the shear box and the specimen shear surface or due to sample leakage, and is measured by the horizontal load cell installed on the horizontal rod. In addition, we will provide a compact automatic repeated single-side shear test device that can subtract the measured frictional force from the total shearing force and thereby completely eliminate the influence of frictional force, which is a measurement error, and solve the above problems Is. Also, to provide a small automatic repetitive one-sided shear test device that can prevent a decrease in the friction reduction effect due to an increase in the number of repetitions by applying Teflon processing that does not reduce the friction reduction effect in the practical range (cumulative horizontal displacement amount of about 500 mm). With the goal. In addition, the use of a digital servo motor that controls the loading of vertical force by a computer eliminates the need for a conventional compressor, and requires no skill in the close contact between the specimen and the vertical loading plate at the start of the test. The loading plate can be fixed in a simple manner, and the constant volume condition can be set easily. In addition, the displacement is calculated from the number of rotations of the rod using a digital servo motor, so there is no need for a displacement meter for vertical displacement measurement. An object is to provide an apparatus.
[0005]
[Means for Solving the Problems]
Therefore, the technical solution adopted by the present invention is:
Vertical shear boxes that can be displaced in different directions in a horizontal plane, high-rigidity load cells that are arranged in four locations facing each other, and specimens that are placed between the upper and lower shear boxes A shearing force applying means capable of applying a shearing force, a horizontal load cell for measuring a shearing force generated in the specimen, a vertical force applying means for applying a vertical force to the specimen, A vertical load cell that measures the vertical force generated in the specimen, and by subtracting the frictional force measured by the high-rigidity load cells arranged at the four locations from the total shear force measured by the horizontal load cell , This is a small automatic repeated single-sided shear test apparatus characterized by obtaining a shearing force .
The shearing force applying means is constituted by a variable motor, and the vertical force applying means is constituted by a digital servo motor .
In addition, it is a small automatic repetitive one-side shear test apparatus characterized in that Teflon processing is performed on opposing surfaces of each of the round shear boxes.
[0006]
Embodiment
Hereinafter, a configuration of a small-sized repeated one-surface shear test according to the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a repetitive single surface shear tester as an embodiment. In the figure, 1 is a control box, 2 is a personal computer, 3 is an A / D converter, 4 is a load cell converter, 5 is a digital servo motor, 6 is a variable motor, 7 is a horizontal load cell for measuring shear force, and 8 is a spacer. , 9 is a shear box, 10 is a displacement meter for measuring horizontal displacement, 11 is an automatic stop device, and 12 is a vertical load cell for measuring a vertical force, and these constitute a one-side shear tester.
[0007]
The shear box 9 is configured as a square or round shear box so that a test can be performed with two types of cross-sectional shapes of the specimen, square and round. Explaining the configuration of the square shear box, Fig. 2 is a cross-sectional side view of the shear box with the upper and lower shear boxes displaced (when measuring peak strength and full softening strength), and Fig. 3 is a shear box with the upper and lower shear boxes overlapping. FIG. 4 is a side sectional view (at the time of residual strength measurement), FIG. 4 is an AA arrow view in FIG. 2, and FIG. 5R> 5 is a BB arrow view in FIG. 2 and FIG. 3 explain the position of the shear box when measuring “friction between specimen and shear box” and “friction due to sample leakage”. Both are applied with normal force. Each of the upper and lower shear box boxes 9A and 9B has a specimen storage space 9C at its center as shown in the figure, and is opposed to the four places of the storage space 9C as shown in FIGS. A small high-rigidity load cell 22 is built in, and the frictional force between the shearing box and the specimen shearing surface when the shearing box is relatively displaced and the frictional force due to sample leakage are measured with such a configuration. Can do. The frictional force measured by the high-rigidity load cell 22 is the frictional force between the shearing box and the specimen shear surface when the shearing box is relatively displaced as shown in FIG. 2, and as shown in FIG. When the relative displacement is zero, the frictional force between the sample leaked from the gap between the upper and lower shear boxes and the shear box. The former is used for correction of peak intensity and complete softening intensity, and the latter is used for correction of residual intensity.
[0008]
Further, as shown in FIG. 6, the round shear box is composed of upper and lower shear boxes 9A and 9B as in the case of the square shear box, and a specimen storage space 9C having a predetermined diameter is formed in each shear box, Further, on the opposing surfaces of the shear boxes, a Teflon process is applied to the shear surface portion in order to reduce friction between the shear box and the specimen shear surface. In addition, in order to test the slip surface sample, the side of the shear box is visualized with an acrylic plate 9D so that the slip surface and the shear surface of the shear box can be matched, and the shear box bottom plate 9E is moved up and down using screws. It is set to be Ru configuration.
[0009]
Note that the gap between the upper and lower sides of the square shear box and the round shear box can be set to 0.01 mm, 0.2 mm, 0.5 mm, 1.0 mm, for example, by sandwiching a gap spacer between the shear box and the fixed plate. It can be adjusted. Further, the material to be applied to reduce the friction between the shear box and the specimen shear surface is not limited to Teflon, and other lubricants can be used.
[0010]
In this apparatus, as a vertical force loading system, as shown in FIG. 1, a high-precision digital servo motor (vertical force applying means) 5 capable of applying a vertical force to the specimen in the shear box is disposed above the shear box 9. Furthermore, a displacement control system is adopted in which a vertical load cell 12 for measuring a vertical force is disposed below the shear box. The conventional apparatus generally uses a stress control system. In this displacement system, a flat high-rigidity load cell is used as the vertical load cell 12 for measuring the vertical force, and a high-precision digital servo motor 5 is used by the personal computer 2. To control. For this reason, setting of constant volume conditions is simple, no skill is required for the close contact between the test specimen and the vertical load loading plate at the start of the test, and the displacement amount is determined from the number of rotations of the rod. There are various advantages such as being unnecessary. The high-rigidity load cell uses a very small displacement of 10 μm in the normal measurement range (0 to 300 kgf), and the lower shear box 9B is mounted directly on the vertical load cell 12 to make it independent from other parts. Therefore, measurement can be performed without being affected by peripheral friction in the shear box.
[0011]
Moreover, a variable motor (shearing force applying means) 6 is employed as a device for applying a shearing force to the specimen, and the output shaft of the variable motor 6 is connected via a rod 6A and a horizontal load cell 7 for measuring the shearing force. The rod 6A is connected to a shear box, and an automatic stop device 11 is provided for the case where the rod 6A does not stop even if the moving amount exceeds the set amount. The horizontal load cell 7 uses a flat high-rigidity load cell, and the horizontal displacement of the shear box is measured by a displacement meter 10 for measuring horizontal displacement. The variable motor 6 has a displacement amount and a rotation direction controlled by the personal computer 2 and can set a horizontal displacement amount of a large displacement at the time of shearing and a continuous repetition number. The shear force is obtained by subtracting the friction force measured by the above-described high-rigidity load cell 22 built in the shear box from the shear force measured by the horizontal load cell 7. As a result, the peak strength and the fully softened strength are the values obtained by subtracting the friction force between the shear box and the specimen shear surface from the measured shear force, and the residual strength is also the value obtained by subtracting the friction force at the sample leakage part. Yes.
[0012]
The operation of the above apparatus will be described. The specimen is stored in the shear box, the high-precision digital servo motor 5 is driven by the personal computer 2, a predetermined vertical force is applied to the specimen at the start of the test, and the vertical force at this time is measured by the vertical load cell 12. . Since this device uses a high-precision digital servo motor, there is no need for close contact between the specimen and the vertical load loading plate, and the displacement is determined from the number of rotations of the rod. Is no longer needed. Further, the variable motor 6 is driven by control from the personal computer 2 to repeatedly apply a shearing force to the specimen. The shear force at this time is measured by a horizontal load cell 7 for measuring the shear force. Further, the frictional force between the shearing box and the specimen shear surface when the shearing box is relatively displaced and the frictional force due to sample leakage are measured by the above-described high-rigidity load cell 22 built in the shearing box.
[0013]
The actual shearing force is obtained by subtracting the frictional force measured by the high-rigidity load cell 22 built in the aforementioned shear box from the total shearing force measured by the horizontal load cell 7 for measuring shearing force. Thereby, the influence of the frictional force which is a measurement error can be completely removed. That is, the peak strength and the full softening strength are values obtained by subtracting the frictional force between the shear box and the specimen shear surface from the measured shearing force, and the residual strength is a value obtained by subtracting the frictional force at the sample leakage portion. As described above, the present apparatus can measure and correct the error factors, thereby more accurately measuring the peak strength, complete softening strength, and residual strength of viscous soil and sandy soil. Further, by combining the latest measurement / control equipment and personal computer control, it becomes possible to reduce variations in measured values depending on the degree of skill.
[0014]
As described above, the embodiment according to the present invention has been described, but in the small-sized repetitive single-surface shear tester, the number of built-in load cells, the arrangement location, and the like can be freely changed depending on the shape of the shear box, etc. It is also possible to use a dedicated electronic control circuit or the like instead of the personal computer. Furthermore, the present invention may be implemented in any other form without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner.
[0015]
【The invention's effect】
As described in detail above, according to the present invention, the frictional force acting between the upper and lower shear boxes and the specimen, which has been a drawback of the conventional single-surface shear tester, can be measured by a load cell built in the shear box. Thus, only the shearing force acting between the specimen shear surfaces can be obtained. These frictions are friction acting between the shear box and the specimen shear surface when the shear box is relatively displaced, and when the relative displacement of the shear box is zero, the leaked specimen acts between the shear box and the shear box. Friction. The former is used for correction of peak intensity and complete softening intensity, and the latter is used for correction of residual intensity. The round shear box is subjected to Teflon processing on the shear surface portion, and friction between the shear box and the specimen shear surface can be reduced. This device is lightweight and compact and can be brought into the field. Data recording and control during testing (consolidation constant pressure condition / consolidation constant volume condition) are automated by a personal computer. By adopting the displacement control method (digital servo motor) in the vertical force loading system, the configuration of the device is simple and the control accuracy is greatly improved . And the like.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a repetitive single surface shear tester as an embodiment.
FIG. 2 is a side sectional view showing a state in which a shearing force is applied to a specimen.
FIG. 3 is a side sectional view showing a state in which a vertical force is applied to the specimen.
4 is an AA arrow view in FIG. 2. FIG.
FIG. 5 is a view taken along arrow BB in FIG. 2;
FIG. 6 is a cross-sectional view of a round shear box.
[Explanation of symbols]
1 Control Box 2 Personal Computer 3 A / D Converter 4 Load Cell Converter 5 Digital Servo Motor 6 Variable Motor 7 Horizontal Load Cell for Measuring Shear Force 8 Spacer 9 Shear Box 9A Upper Shear Box 9B Lower Shear Box 9C Specimen Storage Space 9D Acrylic Plate 9E Bottom plate 10 Displacement meter for horizontal displacement measurement 11 Automatic stop device 12 Vertical load cell for measuring vertical force 21 Specimen 22 High-rigidity load cell 23 Teflon machined part

Claims (3)

Vertical shear boxes that can be displaced in different directions in a horizontal plane, high-rigidity load cells that are arranged in four locations facing each other, and specimens that are placed between the upper and lower shear boxes A shearing force applying means capable of applying a shearing force, a horizontal load cell for measuring a shearing force generated in the specimen, a vertical force applying means for applying a vertical force to the specimen, A vertical load cell that measures the vertical force generated in the specimen, and by subtracting the frictional force measured by the high-rigidity load cells arranged at the four locations from the total shear force measured by the horizontal load cell , A small automatic repetitive one-sided shear tester characterized by determining the shear force. 2. The small automatic repetitive one-side shear test apparatus according to claim 1, wherein the shearing force applying means is constituted by a variable motor, and the vertical force applying means is constituted by a digital servo motor. 3. The small automatic repeated single face shear test apparatus according to claim 1 or 2, wherein the opposing faces of each of the round shear boxes are teflon processed.

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