岩石冻融力学实验及损伤扩展特性

Freeze-thaw cycling and mechanical experiment and damage propagation characteristics of rock

通过红砂岩和页岩两种岩石饱水后的冻融力学实验,系统研究了岩性及冻融循环等对岩石损伤力学特性的影响;充分考虑岩石细观结构的非均匀性,运用宏观唯象损伤力学和非平衡统计的概念和方法,得到了冻融受荷岩石的损伤演化方程;应用推广后的应变等价原理,对不同冻融次数下受荷岩石应力与应变的变化规律,得到统一的损伤扩展本构关系;探讨了岩石材料细观结构损伤及其诱发的材料宏观力学行为.研究表明:岩石的冻融损伤劣化模式为:剥落模式、断裂模式和裂纹模式;冻融循环导致岩石物理力学性能的不可逆劣化;材料内部初始的细观差异经过损伤的非线性演化,表现出终态的宏观差异;冻融与荷载的耦合效应使总损伤有所弱化;损伤模型预测的岩石损伤特性符合实际冻融破坏状况.

Baced on the freeze-thaw cycling and mechanical experiment for two types of rocks on water-saturated state,the influence on rock damage mechanical characteristics of the lithology and freeze-thaw cycles were studied systematically.Using the concepts and methods of macro phenomenological damage mechanics and non-equilibrium statistics,the damage evolution equation was given considering the heterogeneity of rock at mesoscopic level.The unified damage propagation constitutive relation of freeze-thaw and loaded rock under different free-thaw cycles was established by the generalized theory of strain equality.The evolutionary route of micro-structural damage and materials macro mechanical properties for the rock were discussed.The results show that three deterioration modes of freeze-thaw damage are the scaling mode,fracturing mode and crack mode.Freeze-thaw damage leads to irreversible deterioration on physical and mechanical properties for rock.Through the nonlinear evolution of damage,the initial microscopic differences within the material show the macroscopic differences in the final state.The coupling effect of freeze-thaw and load weakens the total damage of rock.The damage characteristics predicted by the damage model are in good agreement with the actual freeze-thaw breakage.