Freeze-thaw failure characteristics and strength loss of non-penetrating fractured rock mass with different fracture densities

Abstract

Rock mass usually contains cracks, joints and other defects with different density and spatial combination characteristics in the diagenetic process. Under the freeze–thaw effect, they continue to expand and connect, which continuously weakens the strength property and poses a serious threat to the stability of rock mass. Previous studies paid more attentions to the strength reduction of rock, failing to directly reflecting the freeze–thaw damage characteristics of rock mass. In this paper, the freeze–thaw failure characteristics and strength loss of non-penetrating fractured rock mass with different fracture densities were studied by means of theoretical derivation and laboratory tests. Firstly, non-penetrating fractured rock mass samples with different fracture conditions were prepared. Then the freeze–thaw samples were subjected to laboratory compression tests and the loss of uniaxial compressive strength was measured. On this basis, the theoretical values of geological strength index GSI was calculated for the samples, and the rough prediction empirical model of GSI for non-penetrating fractured rock mass treated with different freeze–thaw cycles was obtained through data fitting. Finally, by combining the apparent observation method with acoustic emission monitoring technique, the effects of freeze–thaw cycles and fracture density on the failure characteristics of non-penetrating fractured rock mass samples were analyzed comprehensively from both the macro and micro perspectives.