Portable rock mass structural plane direct shear test apparatus for field and indoor use

Abstract

The invention provides a portable rock mass structural plane direct shear test apparatus for field and indoor use. The apparatus comprises a sample preparation shear box and a shear test device. Specifically, the sample preparation shear box is mainly composed of a shear box housing, mould stripping pieces fixed by knobs and the shear box housing, and clamping pieces positioned at the ends of fixation screw rods that are mounted on the mould stripping pieces; the shear test device mainly consists of a shear test device outer frame, a vertical bearing plate, a horizontal pressure bearing instrument, sensors and jacks, with the vertical bearing plate mounted at the upper part of the shear test device outer frame and between a sensor and a jack, and the horizontal pressure bearing instrumentdisposed on a rolling shaft unit in the shear test device. Used in field or indoor rock mass structural plane direct shear tests, the apparatus of the invention can save sample preparation time, thusbeing suitable for rapid structural plane direct shear tests. The apparatus provided in the invention can improve the accuracy and convenience of structural plane direct shear tests, and has the advantages of simple structure, easy manufacturing, convenient operation and low cost, etc.

Description

technical field [0001] The invention relates to the field of rock mechanics tests, in particular to a novel portable structural surface direct shear instrument for obtaining structural surface shear strength parameters and deformation parameters in rock mechanics tests. Background technique [0002] The traditional portable structural surface direct shear tester has the following disadvantages: [0003] (1) When pouring, add a small amount of cement mortar to half of the sample mold, put the sample in the center, make the sheared surface 4-5mm higher than the frame of the sample mold, and make it horizontal; at the same time, keep the shear direction in line with the mold The direction of the long side of the frame is consistent, and then the cement mortar is injected to fill and compact. When completing the above operation steps, due to the visual error of the human eye, it is difficult to ensure the level of the structural surface. Through the statistical work of the mea...

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Problems solved by technology

When completing the above operation steps, due to the visual error of the human eye, it is difficult to ensure the level of the structural surface

Through the statistical work of the measurement data of a large number of structural surface samples prepared by pouring, it is found that the prepared structural surface samples generally have an error angle (the angle between the structural surface and the horizontal plane), which is about 5°, and it is impossible to accurately make the structural surface and the horizontal plane. horizontal plane parallel

During the test, due to the influence of the error angle, the vertical pressure and horizontal pressure applied by the vertical and horizontal loading systems will produce stress decomposition at the structural surface. The actual stress on the structural surface is different from the measured stress value. Finally, the shear strength parameters of the structural surface obtained through the analysis of the test data will inevitably have errors

[0004] (2) Due to the problem of the mold itself, after demoulding, the size of the sample and the shearing device of the structural surface direct shear tester are inconsistent. It is often necessary to grind the sample before doing the shear test, which may even cause the structural surface to be in shear. Misalignment occurs before cutting, resulting in the scrapping of samples

[0005] (3) The horizontal force applied by the direct shear tester on the structural surface will cause the movement of the upper structure, so that the jack will also slide relative to each other, so additional torque will be generated, which will affect the test results

[0006] (4) The structural surface direct shear tester can move without restriction under the action of horizontal force. If excessive shear displacement occurs during the test, it is not only meaningless, but also interferes with the correct reading

[0007] (5) After the structural surface is sampled, the disturbance of the structural surface sample due to human factors (such as handling, etc.) will have a greater impact on the strength test results of the structural surface

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