温度梯度水分扩散对双重孔隙岩体中THM耦合影响的有限元分析

FEM ANALYSES FOR INFLUENCE OF THERMAL WATER DIFFUSIVITY ON THM COUPLING IN DUAL-POROSITY ROCK MASS

建立了一种饱和-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,并研制出相应的二维有限元程序.通过一个假定的位于非饱和双重孔隙-裂隙岩体中的高放废物地质处置库算例,就温度梯度水分扩散系数不同的三种工况,考察了岩体中的温度、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:各工况计算域中温度场及应力场基本相同,当岩体温度梯度水分扩散系数较大时,近场的负孔隙水压力上升到很高的数值,负裂隙水压力有所下降,饱和度亦有相应的变化,当温度梯度水分扩散系数小到一定程度后,其影响也将逐渐消失.

A coupled thermo-hydro-mechanical model of dual-porosity medium for saturated-unsaturated ubiquitous-joint rock mass was established,and the relative two-dimensional FEM program was developed.Taking a hypothetical nuclear waste repository in an unsaturated dual-porosity rock mass as example,Three different operating cases were simulated numerically.Those factors,the temperatures,pore pressure,saturations,flow velocities,principal stresses,etc,in the rock mass were investigated.The results show：1） the temperature fields and the stress fields under three cases are almost same;2） when the thermal water diffusivity of rock mass is larger,the negative pore pressures in near field reach very high values,while the negative fracture pressures decrease a little and the saturate degrees change accordingly;3） after the thermal water diffusivity becomes small to a certain value its influence will disappear.