模拟热–水–应力耦合作用的三维节理单元及其数值分析

对于具有相同厚度的空间8节点等参数节理单元,考虑温度和孔隙水压力的影响,将其的应力–位移关系加以拓展,建立了相应的应力平衡方程、水连续性方程、能量守恒方程,使之可用于分析饱和–非饱和岩体中存在不连续面时的热–水–应力耦合问题,并结合实体单元,研制出相应的三维有限元程序。针对一个假定的核废物地质处置模型,通过有、无节理的热–水–应力耦合过程数值分析,显示与无节理的情况相比,由于节理的存在使得近场岩体中的温度、应力及水流速度的分布与数值都发生了明显的变化,特别是节理附近的岩体中有某种水流"冷却"作用和一定程度的应力集中现象,其它部位岩体的应力也有所增加。

3D joint elements and relevant numerical analysis for simulating coupled thermo-hydro-mechanical processes

Considering the influence of temperature and pore pressure, the stress-displacement relationship of a 8-node isoparametric space joint element with a constant thickness is expanded, so the momentum equilibrium equation, the continuity equation for water and the energy balance equation are established correspondingly for analysis of the coupled thermo-hydro-mechanical processes in saturated-unsaturated rockmass with discontinuities. Combining the joint elements with the solid elements, a relative 3D FEM code is developed. Against an assumed model of geological disposal of nuclear waste, numerical analyses are carried out for the cases with and without joints. The computed results show: compared with the case without joints, the existence of joints causes obvious changes of the distributions and the values of temperature, stresses and velocities of water flows in the near-field rockmass, and especially some cooling effects of water flows and stress concentrations to a certain extent in the rockmass near the joints, and the stresses in other parts of the rockmass also increase.