高温作用下页岩动态力学特性及微观损伤特征研究OACSTPCD

The microscopic damage characteristics and macroscopic mechanical properties of shale are closely related under the coupling effect of temperature and impact load.To study the dynamic characteristics and microscopic damage features of shale under high temperature,dynamic impact compression experiments were conducted on shale samples at room temperature(25℃)and after high-temperature treatment(200℃,400℃,600℃,and 800℃)using the Split Hopkinson Pressure Bar(SHPB)experimental system.X-ray diffraction(XRD)and scanning electron microscopy(SEM)were employed to analyze the microstructure of shale samples subjected to different temperatures.The results showed that under the same impact pressure conditions,the dynamic compressive strength and elastic modulus of the samples gradually decreased with increasing temperature,leading to the deterioration of shale strength and increased fragmentation.At a constant temperature,as the impact pressure increased,the strength and deformation of the samples continuously increased,exhibiting a significant strain rate strengthening effect,and the higher the impact pressure,the more pronounced the temperature deterioration effect.With the increase in impact pressure,the transgranular fracture phenomenon in shale samples increased,while with the rise in temperature,a dramatic change in the dynamic properties of shale occured at 400℃.At 600～800℃,plastic damage features represented by dimples and slip separation appear.The change in mineral composition structure caused by temperature was the main reason for the variation in the mechanical properties of shale.