冻融与荷载耦合作用下岩石损伤模型的研究

 针对寒区工程结构的冻融受荷岩石，提出冻融损伤、受荷损伤与总损伤的概念，拓展损伤变量的内涵；以岩石的初始损伤状态为基准状态，充分考虑岩石细观结构的非均匀性，运用损伤力学理论及推广后的应变等价原理，建立冻融受荷岩石损伤模型；通过损伤变量及本构方程来描述岩石材料细观结构的损伤演化及其宏观损伤行为，与岩石实际冻融破坏情况符合较好。研究结果表明：寒区工程结构的受荷岩石，其力学性能由冻融因子、荷载因子及其耦合效应所决定；冻融与荷载的共同作用使岩石总损伤加剧，并表现出明显的非线性特征，而其耦合效应使总损伤有所弱化；岩石的岩性和初始损伤状态确定各影响因素的权重，表现出不同的损伤扩展特性；相比而言，砂岩对冻融循环更敏感，而受荷损伤最终导致页岩破坏。

RESEARCH ON DAMAGE MODEL OF ROCK UNDER COUPLING ACTION OF FREEZE-THAW AND LOAD

For freeze-thaw and loaded rock in engineering structures in cold regions,a damage variable is proposed with a new meaning,and three new conceptions are put forward,which are freeze-thaw damage,loaded damage and total damage. Defining the initial damage state as basic state,the damage model of freeze-thaw and loaded rock is established considering the heterogeneity of rock at mesoscopic level using damage mechanical theory and generalized principle of strain equality. The damage evolutions of meso-structure and macro-damage behaviors of rocks are described by damage variable and constitutive equation,which are in good agreement with the actual freeze-thaw breakage. It is shown that the mechanical properties of freeze-thaw and loaded rocks in engineering structures are determined by freeze-thaw,load and the coupling effects. The combined effect of freeze-thaw and load in the total damage of rock has obvious nonlinear properties,but the coupling effect will weaken the total damage. The weights of influence factors are determined by the lithology and initial damage states of the rocks,so the rock has different damage propagation characteristics. In comparison,sandstone is more sensitive to the freeze- thaw cycles,and load damage will lead to the destruction of shale eventually.