The Effects of Seasonal Temperature and Humidity Cycles on the Shear Deterioration and Erosion of Pisha Sandstone

Taking the exposed Pisha Sandstone in Baojiagou Basin, Zhungeer Banner, Inner Mongolia as the research object, Through indoor simulation of extreme temperature and humidity coupling cycles of the four seasons, direct shear tests were conducted by setting 5, 10, 15, 20, and 25 cycles.Analyze the attenuation characteristics of shear strength parameters, the degradation rate, erosion sensitivity, and the relationship between mechanical parameters and erosion indicators. The results indicate:The cyclic variation of temperature and humidity throughout the four seasons significantly reduces the shear strength of Pisha Sandstone, The degree of deterioration, ranked according to the rate of deterioration under peak stress, shows a seasonal characteristic of summer > winter > autumn > spring.The peak stress degradation rates are 3.29, 2.94, 1.43, and 1.08 kPa/cycle; The shear strength shows a decay pattern with seasonal differences over the number of cycles: linear uniform decay in spring, rapid exponential decay in summer, steady decay in autumn, and a combination of linear and exponential decay in winter; The degradation of the shear strength of Pisha Sandstone has significant stages, The 0-10 cycle range is the rapid degradation phase, 10-25 cycles is the stable accumulation phase; Cohesion, internal friction angle, elastic stiffness, and erosion sensitivity are extremely significantly negatively correlated, and are core indicators affecting the anti-gravitational erosion capacity of Pisha Sandstone.