Mechanism and laws of deterioration and damage of gneisses under cyclic loading

The collapses and landslides of gneiss in Taxian area of Xinjiang are mainly caused by the deterioration of rock mass under the long-term circulation of seismic force. In order to reveal the mechanism of deterioration and damage of gneiss under earthquake in Taxian area, constant amplitude cyclic loading tests and triaxial compression tests were carried out on gneiss samples under different stress levels in this paper. And the variation rules of hysteretic cycle, damping parameters and triaxial compressive strength before and after constant amplitude cyclic loading were analyzed. The results show that:the damping ratio and damping coefficient of gneiss decrease with the increase of cyclic loading and increase with the increase of stress level; after cyclic loading, the triaxial compressive strength of gneiss decreases significantly, and the higher the stress level is, the greater the reduction range is; in addition, the friction of mineral particles in gneiss, the opening and closing of primary micro-fissures and pores, and the generation and development of secondary fissures are the main mechanisms leading to their deterioration and damage. In short, under the long-term earthquake force, the mechanical property of gneiss in the study area has been reduced due to internal deterioration and damage, which is one of the main reasons for the extensive development of large-scale collapses, landslides and other geological disasters in this area.