软岩冻融损伤的水-热-力耦合研究初探

STUDY ON LIQUID-THERMAL-STRESS COUPLING OF FREEZING-THAWING DAMAGE OF SOFT ROCK

冻融力学研究正温、负温环境交替变化对材料的物理力学性质的影响。由于软岩为强度低、孔隙度大、胶结程度差、含有大量膨胀性粘土矿物的松散、软弱岩层。因此,软岩的水-热-力耦合不是一个简单的过程。初步提出了软岩的水-热迁移机理,进而提出了软岩水-热-力耦合的基本数学模型。最后用ANSYS软件模拟了隧道围岩温度场与应力场,得到了隧道围岩冻胀力的分布趋势。

Freezing-thawing environment affects the stability of soft rocks in cold region.Because soft rocks have low strength and high porosity and contain large amount of expansive clay minerals,the freezing-thawing process of soft rock is complicated.Based on physical properties of soft rock and water-rock interaction and theories on continuum medium,heat conduction and mass transfer,basic equations of freezing-thawing process are established.The equations consider water movement,heat conduct,phase change of water and relevant latent heat.The FEM software,ANSYS,is employed to simulate the temperature distribution of soft rock tunnel and temperature-stress field.Simulation results agree with the practice.Liquid-thermal-stress coupling models are set up,in which soft rocks is taken as 3D elasticity body and the damage of soft rocks is considered.The distribution of frost-heaving force is determined by analytical method,and the damage parameters and elastic moduli of soft rocks in different stages are determined by using the equation of rheological damage.