摘要
基于岩石加速蠕变阶段的力学状态特征,提出一个非线性黏滞系数的牛顿体,建立一个新的岩石非线性黏弹塑性蠕变模型,该模型能够很好地模拟岩石非线性蠕变的衰减、稳态和加速蠕变3个阶段,而且在一定条件下该模型可以蜕变为Burgers或西原模型;基于提出的非线性蠕变模型,推导岩石在不同恒定荷载情况下的蠕变方程,分析岩石蠕变的非线性特征。采用岩石全自动三轴流变伺服仪,对锦屏一级水电站工程左岸高边坡砂板岩和大理岩进行三轴蠕变力学试验,获得典型的岩石加速蠕变曲线。将Quasi-Newton算法(BFGS)嵌入到最小二乘法(LSM)中,提出BFGS-LSM算法,该方法能够快速准确地逼近精确解,并且不易收敛于局部极小点;采用该算法,利用获得的岩石全程三轴蠕变试验结果,对岩石非线性黏弹塑性蠕变模型参数进行辨识,辨识的结果和试验曲线吻合较好。
Based on the mechanical behaviors of rock at the accelerating creep stage, a nonlinear coefficient of viscosity component is proposed. By using this proposed component, a new nonlinear visicoelasto-plastic creep model of rock is put forward; and the model can describe the three stages of rock nonlinear creep. Under certain condition, the model can be disintegrated into Burgers model or Nishihara model. The creep equation of rock at the constant stress is deduced; and the nonlinear creep properties of rock are studied in accordance with the proposed nonlinear creep constitutive model. Creep experiments are carried out for sandstone and marble specimens from left bank high slope of Jinping First Stage Hydropower Project by using the rock servo-controlled rheology testing machine; and the typical triaxial acceleration creep curves of rock are obtained. A new BFGS-LSM algorithm is brought forward by combining the quasi-Newton algorithm（BFGS）with the least square method（LSM）. Throughout this algorithm, the exact solution can be fast approximated, which is not easily converged to the local minimum. The algorithm is adopted to investigate the triaxial creep tests of rock; and the related creep parameters of rock specimens using the proposed model are identified. The result shows that the new nonlinear viscoelastoplastic creep model of rock accords better with the creep test curves.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2008年第4期832-839,共8页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金重点项目(50539110)
国家自然科学基金资助项目(50709008)
关键词
岩石力学
非线性牛顿体
黏弹塑性
蠕变模型
参数识别
rock mechanics
nonlinear Newton body
viscoelasto-plasticity
creep model
parameter identification
