遍有节理岩体的双重孔隙-裂隙介质热-水-应力耦合模型及有限元分析

COUPLED THERMO-HYDRO-MECHANICAL MODEL AND FINITE ELEMENT ANALYSES OF DUAL-POROSITY FRACTURED MEDIUM FOR UBIQUITOUS-JOINT ROCK MASS

建立一种饱和-非饱和遍有节理岩体的双重孔隙-裂隙介质热-水-应力耦合模型,其特点是应力场和温度场是单一的,但具有不同的孔隙渗流场和裂隙渗流场,以及可考虑裂隙的组数、间距、方向、连通率和刚度对本构关系的影响,并研制出相应的二维有限元程序。针对一个假定的高放废物地质处置库,就岩体为双重介质和单重介质2种工况进行数值分析,考察缓冲层和岩体中的温度、孔隙水压力、饱和度、地下水流速和主应力的变化、分布情况。结果显示,地下水由双重介质进入缓冲层中要快得多,2种工况的计算域中温度差别不大,但缓冲层及附近部位的主应力大小及分布有显著不同,单重介质的应力集中程度要大。

A kind of coupled thermo-hydro-mechanical model of dual-porosity fractured medium for saturated- unsaturated ubiquitous-joint rock mass, in which the stress field and the temperature field are single, but the seepage field is double, and the influences of sets, spaces, angles, continuity ratios, stiffnesses of the fractures on the constitutive relationship of the media can be considered, is established; and also the relative two- dimensional program of finite element method is developed. Taking an assumed nuclear waste repository for example, in which two cases of rock mass including dual-porosity medium and single-porosity medium respectively are simulated; and the temperatures, pore pressures, saturations, flow velocities and principal stresses in the buffer and rock mass are investigated. The results show that water flows from the dual-porosity medium into the buffer are quicker by far; the difference of temperatures in the calculation domain of two cases is very small, but there are obvious variations in magnitudes and distributions of the principal stresses in the near field for the two kinds of media; and the stress concentration in the single-porosity rock mass is larger.