冻融作用下含冰裂隙花岗岩动态抗拉力学特性研究

The natural fractured rock mass in the alpine region is easy to form ice-filled fractured rock mass under the action of groundwater and low temperature,which seriously affects the stability of rock mass under dynamic loads such as blasting.Studying the tensile mechanical properties of ice-filled fractured rocks under dynamic loading is significant for understanding the fracture and instability of freeze-thaw treated rocks.This study focuses on ice-filled fractured granite,using CT scanning to quantify the degradation of freeze-thaw damage,and employing a Pendulum-driven Split Hopkinson Pressure Bar(SHPB)testing device to investigate the damage characteristics under different freeze-thaw cycles and loading rates.High-speed photography and scanning electron microscopy are utilized to explore the fracture characteristics of the granite.The study reveals that the dynamic tensile strength of ice-filled fractured granite decreases exponentially with an increase in freeze-thaw cycles at a given loading rate,showing a significant negative correlation with changes in longitudinal wave velocity and porosity.Dynamic tensile strength attenuation models are established based on these parameters,reflecting the degradation trend.A predictive equation for the dynamic tensile strength of freeze-thaw fractured rocks is developed,incorporating longitudinal wave velocity and porosity as freeze-thaw damage parameters,and the ratio of dynamic to static loading rates as a dynamic load damage parameter,capturing the effects of freeze-thaw cycles and loading rates.Compared to intact and single-fracture samples,ice in the fractures provides some support and consolidation,but the guiding effect of pre-existing fractures remains dominant in the fracture process.