STUDY OF UNLOADING TRIAXIAL RHEOLOGICAL TESTS AND ITS NONLINEAR DAMAGE CONSTITUTIVE MODEL OF JINPING HYDROPOWER STATION GREEN SANDSTONE
ZHU Jiebing，WANG Bin，WU Aiqing
(Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources，Yangtze River Scientific Research Institute，Wuhan，Hubei 430010，China)
Abstract：Taking green sandstone samples from the diversion tunnel of Jinping II hydropower station as research objective，the unloading triaxial rheological tests by keeping axial stress and unloading lateral stress by steps are performed in laboratory. According to experimental results，the creep laws of axial and lateral deformations under unloading stress path are studied. Development of lateral plastic deformation is more rapid than that of the axial direction；and the response to failure in lateral direction is more obvious than that in axial direction. After detailed research and analysis of the test results，and considering damage effects of rock parameters，the damage evolution equation and nonlinear rheological Burgers model with various parameters are proposed. In the model，the creep parameters of sandstone are weakened with viscous strain gradually，so the deterioration process of the material can be reflected by unsteady creep parameters directly. By taking the sum square of survival difference as optimization objective，the least square embedded in Levenberg-Marquardt(LM) algorithm is adopted to optimize the fitting parameters of models. And then，nonlinear damage rheological constitutive model is established. By comparing with the test data，the fitting curves are well fitted with test data curves；it is shown that the rheological model can preferably present attenuating creep and steady rheological characteristics of Jinping green sandstone.
朱杰兵，汪斌，邬爱清. 锦屏水电站绿砂岩三轴卸荷流变试验及非线性损伤蠕变本构模型研究[J]. 岩石力学与工程学报, 2010, 29(03): 528-534.
ZHU Jiebing，WANG Bin，WU Aiqing. STUDY OF UNLOADING TRIAXIAL RHEOLOGICAL TESTS AND ITS NONLINEAR DAMAGE CONSTITUTIVE MODEL OF JINPING HYDROPOWER STATION GREEN SANDSTONE. , 2010, 29(03): 528-534.
