动载荷和含水率对红砂岩动态强度和变形的影响

Effect of Dynamic Load and Water Content on Dynamic Strength and Deformation of Red Sandstone

地下工程岩体爆破开挖过程中,动荷载和地下水对工程岩体的安全稳定具有显著影响。为揭示动荷载和含水率对岩石的影响特性,采用改进的霍普金森压杆试验装置,用4种不同的冲击速度,在6种含水率工况下对红砂岩进行冲击压缩试验,根据试验中采集到的3组应力波信号,利用三波法将其转化为岩石的动态应力-应变曲线,得到了岩石的动态峰值应力、极值应变和平均应变率等参数。试验结果表明:相同动荷载作用下,随着含水率增加,动态峰值应力逐渐减小,且二者具有良好的指数函数关系;随着含水率增加,岩石动态极值应变线性增加;随着含水率增加,岩石的平均应变率呈指数型增长。随着冲击速度的增大,动态峰值应力、动态极值应变和岩石的平均应变率均增大。研究结果有助于对深部岩石的稳定性进行监测,为工程中的突水突泥等灾害的发生机理及影响因素的研究提供一定参考。

In the process of blasting excavation of underground engineering rock mass,dynamic load and groundwater have a significant impact on the safety and stability of engineering rock mass.In order to reveal the influence characteristics of dynamic load and water content on rock,the improved Hopkinson pressure bar test device was used to carry out the impact compression test of red sandstone under six water content conditions with four different impact velocities.According to the three sets of stress wave signals collected in the test,the three-wave method was used to convert them into the dynamic stress-strain curve of the rock,and the dynamic peak stress,extreme strain and average strain rate of the rock were obtained.The results show that under the same dynamic load,the dynamic peak stress decreases gradually with the increase of water content,and the two have a good exponential function relationship.With the increase of water content,the dynamic extreme strain of rock increases linearly,and the average strain rate increases exponentially.With the increase of impact velocity,the dynamic peak stress,dynamic extreme strain and average strain rate of rock increase.The research results are helpful to monitor the stability of deep rock,and provide some reference for the study of the mechanism and influencing factors of disasters such as water and mud inrush in engineering.