西北人工冻结红砂岩的动态时效损伤模型

为了研究西北人工冻结红砂岩的动态力学特性，采用SHPB试验装置对-15 ℃红砂岩进行单轴冲击压缩试验。对SHPB试验中5组有效数据展开分析，得到了5条不同应变率下的动态应力应变曲线。基于损伤演化及元件模型理论，将冻结红砂岩视为由具有弹性特性、损伤特性、塑性特性及黏滞特性的非均匀质点组成，建立了包含损伤体元件、黏壶及弹簧的时效损伤模型。〖JP2〗研究发现:试件强度与平均应变率呈指数相关，当试件平均应变率较小时，试件的强度变化平缓，在高平均应变率下，试件强度急剧增大，当平均应变率为120.73 s-1时，应力峰值高达84.96 MPa，接近静态抗压强度44.1 MPa的2倍;时效损伤模型较好地反映了在一定范围内的冻结红砂岩应力应变关系。

Time dependent damage model of northwest artificial frozen red sandstone under dynamic loading

In order to study the dynamic mechanical properties of northwest artificial frozen red sandstone,the shock compression tests were conducted on red sandstone at -15 ℃ using SHPB apparatus.In the SHPB tests,five groups of valid test data were analyzed,and five stress-strain curves were obtained with different average strain rates.Based on the damage evolution and the component model theory,the frozen red sandstone is considered as a non-uniform particle composed of elastic,damage,plastic and viscous properties.In this paper,a time dependent damage model which includes the damaged body element,the clay pot and the spring is established.It is found that the strength of the specimen is exponentially correlated with the average strain rate.When the average strain rate is low,the strength of the specimen changes gently,and the strength of the specimen increases sharply at the high average strain rate.When the average strain rate is 120.73 s-1,the peak value of stress is as high as 84.96 MPa,which is about twice of the static compressive strength of 44.1 MPa.The time dependent damage model can reflect the stress-strain relationship of the frozen red sandstone in a certain range.