Method for acquiring dynamic stiffness of rock joint

Abstract

The invention relates to a method for acquiring the dynamic stiffness of a rock joint, and belongs to the technical field of rock mass measurement. The method comprises the following steps: preparing a rock sample containing the joint, carrying out a uniaxial compression test on the rock sample, and determining an equivalent normal stress sigma n and an equivalent tangential stress sigma t on a plane where the joint is located according to an applied compression external load sigma 0; shooting an image of the rock in the compression process, and determining a displacement field and a strain field in the rock test process according to the shot image; determining the thickness of the joint according to the strain field, selecting a plurality of characteristic sections in the length direction of the joint, determining displacements of upper and lower edge measuring points of the characteristic sections, and determining an average normal displacement un and an average tangential displacement ut on a plane where the joint is located; and determining the dynamic normal and tangential stiffness of the joint according to a joint stiffness calculation formula.

Description

technical field [0001] The invention belongs to the technical field of rock mass measurement, and in particular relates to a method for acquiring dynamic stiffness of rock joints. Background technique [0002] Joints widely exist in rock mass, and rock joint stiffness is one of the important parameters to characterize the mechanical properties of joints. At present, the joint stiffness is mainly obtained through field test and indoor test. The field test monitors the vibration waveforms on both sides of the joint through artificial vibration, and calculates the joint stiffness according to the vibration waveform and related assumptions. However, the field test method has many influencing factors, the test conditions are not easy to control, the process is complicated, and the reliability and accuracy of the results are poor. [0003] In laboratory tests, the compression and direct shear tests of intact rocks and jointed rocks are carried out separately, and the test data o...

AI Technical Summary

Problems solved by technology

However, the field test method has many influencing factors, the test conditions are not easy to control, the process is complicated, and the reliability and accuracy of the results are poor.

[0003] In laboratory tests, the compression and direct shear tests of intact rocks and jointed rocks are carried out separately, and the test data of intact samples and jointed samples are combined to determine the normal and tangential stiffness of joints. The existing indoor test method needs to be carried out 4 times. Compression and direct shear tests can only obtain the normal and tangential stiffness of joints, and there are problems such as the joint thickness cannot be determined, and the coupling effect of normal and tangential directions cannot be considered.

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