DAMAGE DEFORMATION CHARACTERISTICS AND ITS STRENGTH CRITERION BASED ON UNLOADING EXPERIMENTS OF GRANITES
LU Yinghui1，LIU Quansheng1，2，HU Yunhua3
(1. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China；2. College of Civil Engineering and Architecture，Shangdong University of Science and Technology，Qingdao，Shandong 266510，China；3. Second Highway Consultants Co.，Ltd.，China Communications Construction Corporation，Wuhan，Hubei 430056，China)
Abstract：Two different unloading tests of granites from the Dagangshan Hydropower Station at Dadu River have been carried out. In order to analyze rock failure mechanism，the damage laws of mechanics and strength parameters，the failure strength criterion during the process of unloading，the conventional triaxial compression tests of granites have been also performed. The results show that：(1) The characteristics of intense rebound deformation，distinct dilatancy and brittleness failure of rock have been observed in two different unloading tests. (2) Compared with the deformation modulus in conventional triaxial compression tests，the deformation modulus at the beginning point of unloading has been degenerated；the relationship between damage factor and initial confining pressure is approximately linear，but little damage is found in the Poisson¢s ratio. (3) During unloading stage，the Poisson¢s ratio rises up continually，and the variation law with the confining pressure can be well described by exponent relation；deformation modulus varies hardly，but at the failure point，it decreases rapidly. (4) In the two different unloading tests under high geostress，the Mogi-Coulomb envelope can match stress circle very well. (5) In the two unloading tests，shear strength parameters have been evaluated by Coulomb laws，and it is founded that the cohesion c decreases，but the inner friction angle increases during unloading；and the variation is dependent of the unloading style. These conclusions have revealed the unloading mechanical properties of granites under high geostress and provided reliable theoretical reference for the numerical simulation about excavation and design for the stability analysis of large-scale hydropower projects in West China.
吕颖慧，刘泉声,胡云华. 基于花岗岩卸荷试验的损伤变形特征及其强度准则[J]. 岩石力学与工程学报, 2009, 28(10): 2096-2103.
LU Yinghui1，LIU Quansheng1，2，HU Yunhua3. DAMAGE DEFORMATION CHARACTERISTICS AND ITS STRENGTH CRITERION BASED ON UNLOADING EXPERIMENTS OF GRANITES. , 2009, 28(10): 2096-2103.
