冲击荷载作用下的煤岩动力学特性及本构模型

为了研究煤岩的动态破坏特征和动力学损伤特性,利用分离式霍普金森压杆(SHPB)和应力加载系统,对煤岩试样进行了冲击试验和单轴压缩试验;根据应力-应变试验曲线的特征,在过应力模型上,应用连续损伤理论与统计强度理论,建立了适合煤岩动力学特性的过应力损伤模型。结果表明:动载作用下,当应变率较小时,煤岩破碎方式与静载作用时间具一定的相似性;随着应变率的增大,动载破坏强度显著增大,动态模量先增大后保持不变,塑性变形先增大后减小,应力-应变曲线具有明显的塑性流动特性。采用建立的煤岩过应力损伤模型本构方程对试验曲线进行拟合,通过两者的对比,验证了模型的正确性。

Dynamic characteristics and constitutive model of coal rock under impact loading

In order to study the dynamic failure characteristics and dynamic damage characteristics of coal rocks, using split Hopkinson pressure bar(SHPB) and stress loading system, impact tests and uniaxial compression experiments were performed on coal rock samples. According to the characteristics of stress-strain experiments curve, based on the overstress model, continuous damage theory and statistical strength theory are applied to establish an overstress damage model suitable for the dynamic characteristics of coal and rock. The results show that under dynamic load, when the strain rate is small, the coal rock crushing method is similar to that under static load;as the strain rate increases, the dynamic load failure strength increases significantly,and the dynamic modulus increases first. It remains the same after being large, the plastic deformation increases first and then decreases, and the stress-strain curve has obvious plastic flow characteristics;the experimental curve is fitted using the established constitutive equation of coal rock overstress damage model, and the comparison between the two verifies the correctness of the model.