基于Cosserat理论的柱状节理岩体本构模型

Constitutive Model of Columnar Jointed Rock Mass Based on Cosserat Theory

柱状节理岩体复杂的各向异性对相关工程设计及施工提出了挑战,准确掌握其各向异性力学参数对降低工程风险十分重要。基于Cosserat理论和Goodman当量叠加原理,首先建立了四棱柱、五棱柱、六棱柱柱状节理岩体二维本构模型。通过引入应力集中系数,将本构关系扩展至三维空间。针对白鹤滩水电站柱状节理岩体,采用3种模型分别计算了工程常数取值,并分析了3种模型计算结果与工程经验取值差异,比较了3种模型各向异性特征。结果表明,3种模型计算值与经验公式估算结果及现场原位承压板试验结果相近,四棱柱、五棱柱、六棱柱柱状节理岩体模型的弹性参数变化曲线分别反映出各模型正交各向异性、准横观各向同性、横观各向同性的各向异性特征。

The complex anisotropy of columnar jointed rock mass poses a challenge to the smooth development of related engineering. It is very important to accurately grasp its anisotropic mechanical parameters to reduce engineering risks. Based on Cosserat theory and Goodman’s equivalent superposition principle, the two-dimensional constitutive model of four-prism, five-prism and six-prism columnar jointed rock mass is firstly established, and the constitutive relation is extended to the three-dimensional space by introducing the stress concentration coefficient. Aiming at the column jointed rock mass of Baihetan hydropower station, the value of engineering constant is calculated by three models, and the difference between the calculation results of three models and the value of engineering experience is analyzed, and the anisotropy characteristics of three models are compared. The results show that the calculated values of the three models are close to those of the empirical formula and the in-situ test results of the bearing plate, and the elastic parameter variation curves of the column-jointed rock mass models of four-prism, five-prism and six-prism respectively reflect the anisotropy, quasi transverse isotropy and transverse isotropy of each model.