RESEARCH ON DAMAGE MODEL OF SINGLE JOINTED ROCK MASSES UNDER COUPLING ACTION OF FREEZE-THAW AND LOADING

For rock masses under freeze-thaw and loading in engineering structures in cold regions,using rock-like materials produced rock specimens with different geometric characteristics,based on the freeze-thaw experiments and uniaxial compression test,the influence of crack dip angle and crack length on the rock masses strength were studied;and combining mesoscopic damage theory and macroscopic statistical damage model,the damage model of freeze-thaw and loading rock masses were established;at the same time,damage degradation mechanism of jointed rock masses under the coupling action of freeze-thaw and loading were discussed. The research results show that:(1) The freeze-thaw damage is a process of fatigue damage;and loading damage is an uneven distribution process of stress field and deformation.(2) Freeze-thaw and loading with different mechanisms promote rock crack initiation and propagation;hence induced damages couple with each other,the coupling of the two will make the total damage deterioration.(3) Crack length and freeze-thaw cycles on total damage is larger;the influence of crack dip angle on the total damage is relatively small.(4) under the same cycles of freeze-thaw,damage degradation of cracking rocks is more serious than the intact samples.