Anisotropic rock joint shear strength study based on sample mould of multi-function undulation structure plane

Discontinuities exist in the rock engineering extensively and their property impacts conspicuously the failure characteristics of rock. A self-developed sample mould with controllable undulation was used to make samples of structure plane with different undulation angle, to carry out shear test in lab, and on the basis of this to study the influence of the undulation angle on shear strength of structure plane. The undulating sample mould has the advantages of higher practicability for making serrated, undulating, regular and irregular discontinuity samples. According to the mould design and the characteristics of actual discontinuities in the field, the samples with undulating angle of 5, 10, 15, 20, 25 and 30 degrees were made rapidly to conduct the direct shear test. The results are in good accordant with the general law of discontinuity shear test, verifying the reliability and practicality of the mould. On the basis of the test results, JRC-JCS model proposed by Barton was used to set up the corresponding relation between the undulating angle and JRC, and taking into account different strength of the anisotropic structure plane, a shear strength formula considering undulating angle has been proposed.