Influence of material composition and structural characteristics of rock on freeze-thaw damage and deterioration of schist

Currently, the researches on influence factors of freeze-thaw damage of rock mainly focus on external cause, while ignoring the internal causes, such as material composition, microstructure, etc, Taking Wudang Group schist in Tongsheng tunnel,Shiyan-Fanging expressway, northwest of Hubei Province as an example, the influences of material composition and structural characteristics (mineralogy and arrangement of mineral particles) on freeze-thaw damage degradation characteristics of schist are compared and analyzed, through indoor tests such as freeze-thaw cycles, uniaxial compression, mineral composition analysis, sliced polarizing microscope tests. The results show that the influences of material composition and structural characteristics are mainly the following two aspects: (1) Particle size and distribution of mineral filled in foliation; (2) Situation of mica orientation. For the former aspect when the particle size of mineral is greater or its distribution is scattered,the particle mineral has strong blocking and binding effect on the deformation of foliation. On the contrary,the blocking and binding effect is weak. For the latter aspect, when the degree of orientation of mica arranged is high, the effect of damage caused by freeze-thaw cycles is more obvious. On the contrary,the effect is not obvious. The results have certain reference significance to the researches on influence factors of rock damage caused by freeze-thaw cycles from internal angle.