Propagation simulation and dilatancy analysis of rock joint using displacement discontinuity method

LI Ke(李科)^{1, 2}, HUANG Lun-hai(黄伦海)¹, HUANG Xing-chun(黄醒春)^{2, 3}

(1. National Engineering Laboratory on Road Tunnel Construction Technology
(China Merchants Chongqing Communications Research & Design Institute), Chongqing 400067, China;
2. School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University,
Shanghai 200240, China;
3. Chinese Underwater Technology Institute, Shanghai Jiao Tong University, Shanghai 200231, China)

Abstract:A revised displacement discontinuity method (DDM) program is developed for the simulation of rock joint propagation and dilatancy analysis. The non-linear joint model used in the program adopts Barton-Bandis normal deformation model, Kulhaway shear deformation model and Mohr-Coulomb criterion. The joint propagation criterion is based on the equivalent stress intensity factor which can be obtained by regression analysis. The simulated rock joint propagation accords well with the existing knowledge. The closure and opening of joint is investigated by DDM, and it is shown that if the opening volume of propagated joint is larger than closure volume of the old joint, the joint dilatancy occurs. The dilatancy condition is mainly controlled by the normal stiffness of the rock joint. When the normal stiffness is larger than the critical value, joint dilatancy occurs. The critical normal stiffness of rock joint changes with the joint-load angle, and joint dilatancy is most possible to occur at 30°.

Key words:joint propagation; joint dilatancy; displacement discontinuity method; non-linear rock joint; numerical simulation