Rock direct shear experiment test piece, test piece clamp and shear testing method thereof

Abstract

The invention relates to a rock direct shear experiment test piece, a test piece clamp and a shear testing method thereof, and belongs to the technical field of rock mechanical testing. The test piececan be directly applied to a triaxial testing machine and comprises a cuboid body; a first cutting groove is formed in the left part of the lower side of the cuboid body; the first cutting groove extends from the side to the internal part of the body in a horizontal direction; the test piece also comprises a second cutting groove; the first cutting groove and the second cutting groove are distributed in a centrally symmetrical mode by taking the center of the body as a center; the length of each cutting groove is equal to the length of the side of the cuboid body; and the width of the cuttinggroove is not more than half of the side length of the bottom surface. The structure is simple and portable; the rock direct shear experiment can be conducted on a triaxial mechanical testing machinewhich only can perform compression; the test purposes of the triaxial mechanical testing machine are enriched; the surface pressure stress of the test piece is provided through confining pressure loading provided by a confining pressure oil source; the pressure stress distribution is more uniformly compared with the axial centralized load loading selected by the traditional direct shear test; thestress distribution uniformity is improved; the high-temperature rock direct shear test can be conducted subsequently; and the test piece is suitable for carrying out the rock direct shear test research.

Description

technical field [0001] The invention belongs to the technical field of rock mechanics testing, and relates to a rock direct shear test specimen, a specimen fixture, an indenter unit for a rock shear test, and a shear test method based on the specimen, which can be used in a conventional triaxial testing machine . Background technique [0002] Shear failure is a failure phenomenon caused by shear stress that causes the rock mass on both sides of the shear plane to displace or expand, and is one of the main modes of major instability and failure of engineering rock mass. Under the action of shear load, the maximum shear stress that the rock can resist shear failure is called the shear strength of the rock. The shear strength of rock represents the ability of rock to resist shear failure and sliding, so it is of great significance to study the shear strength of rock. At present, the methods for studying rock shear strength are divided into two categories: indoor and field tes...

AI Technical Summary

Problems solved by technology

However, the traditional direct shear test method requires specific shear equipment that can provide loading forces in two directions, which is expensive and has a single function

The wedge shear test technique can also realize the rock shear strength test, but when using this test method, the normal pressure and tangential thrust on the surface of the specimen increase in proportion, and the rock shear failure behavior under a certain positive pressure cannot be obtained ( That is, the shear stress-displacement curve of the sample)

[0004] The triaxial press is the basic test equipment for testing the failure behavior and strength of rock, and is widely used in China at present; it is very common to use the triaxial press to test the shear strength and shear failure behavior of rock, but the existing technology cannot test specific normal The shear strength of rock under vertical pressure cannot be obtained, and the relationship between rock shear stress and shear displacement cannot be obtained; especially for transversely isotropic rocks, the traditional technology of rock shear strength testing using triaxial presses is difficult. To determine the accurate shear failure surface, the cohesion and internal friction angle of this type of rock cannot be calculated, which is not conducive to the shear strength test of transversely isotropic rock

In addition, because the triaxial press cannot provide the shear force of the direct shear test, it is difficult to directly put the specimens of the prior art on the traditional triaxial testing machine for the direct shear test of the rock

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