Study on acoustic emission signal and damage characteristics of frozen sandstone under lateral unloading

In order to study the influence of artificial freezing method on the deformation and damage of surrounding rock unloading,the stress change path of surrounding rock is simulated,and the lateral unloading mechanical test and acoustic emission signal monitoring are carried out under different conditions. The results show that the characteristics of total crack number,tensile crack number,cumulative AE count and cumulative AE count of tensile crack are basically the same with time for sandstone under different lateral unloading conditions. The increasing point(point A) of lateral unloading deformation rate of rock sample can be used as fracture warning. The peak stress of lateral unloading of sandstone after freezing is increased by 2.3-3 times. With the increase of initial confining pressure, the tensile action of frozen rock sample is enhanced,the lateral unloading rate is increased,and the tensile crack is reduced. The initial confining pressure and lateral unloading rate of frozen rock sample increase,the peak stress increases,and the failure becomes more severe. Under the same conditions, lateral unloading of rock samples accounts for 52%-72% of the triaxial compression capacity. The damage model is established according to the number of lateral unloading tensile cracks. The model results are very close to the test results before the peak stress,which can characterize the damage fracture characteristics of frozen sandstone under lateral unloading. © 2023 Academia Sinica. All rights reserved.