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Advances in Materials Science and Engineering
Volume 2015, Article ID 982842, 10 pages
Research Article

An Experimental Study on Deformation Fractures of Fissured Rock around Tunnels in True Triaxial Unloads

Department of Engineering Mechanics, Sichuan University, Chengdu 610065, China

Received 12 December 2014; Accepted 9 April 2015

Academic Editor: José L. Ocaña

Copyright © 2015 Meng Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Joints and cracks are frequently encountered in underground rock mass. During the process of tunnel excavations or other underground construction, the rock will be exposed suddenly, and such sudden unloading process will cause crack expansion and destabilize the rock structure. In order to investigate the crack behaviour during this process, a true triaxial loading apparatus with a computer-controlled electrohydraulic servosystem was established, and a series of true triaxial loading and unloading experiments was conducted by using concrete specimens containing inclined cracks with inclinations of 15°, 30°, 45°, 60°, and 75°. The stress-strain behavior and the failure property of rock models during unloading process were obtained, and, additionally, the coefficient of brittle stress drop was investigated. The uniaxial compression tests were simulated by using finite element method.