摘要
以锦屏二级水电站引水隧洞绿砂岩为研究对象,采用恒轴压、逐级卸围压的应力路径开展室内流变试验,研究卸荷条件下的轴向及侧向变形特征。成果表明:侧向塑性变形的发展速率明显比轴向快,岩样破坏前在侧向反应要比轴向更为明显。在对流变试验数据进行深入分析基础上,从材料损伤的角度出发,认为岩石流变力学参数随着黏性应变的负指数形式逐步弱化,从而建立起岩石损伤演化方程及变参数非线性Burgers模型。基于Levenberg-Marquardt(LM)算法,以残差平方和为目标函数,对试验数据开展相应拟合,所获得的参数可较好反映蠕变曲线的非线性特征。经比较,计算曲线与试验点曲线比较接近,说明该流变本构模型能较好的反映出锦屏绿砂岩在卸荷条件下的衰减蠕变阶段和稳定流变特性。
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.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2010年第3期528-534,共7页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金面上项目(40872192)
国际自然科学基金重点项目(50639090)
作者简介
朱杰兵（1970-），男，博士，1992年毕业于山东科技大学岩土工程专业，现任高级工程师，主要从事岩石力学试验与分析方面的研究工作。E—mail：zhujiebing@yahoo．cn
