砂岩黏性对抗拉强度加载率效应影响的试验研究

利用摆锤冲击加载SHPB试验装置,进行砂岩和人造岩心长杆冲击试验和动态巴西盘试验,测试砂岩和人造岩心的黏性系数,分析砂岩和人造岩心强度的加载率效应。利用试验和数值模拟相结合的方法得到绿砂岩、人造岩心A和B的黏性系数分别为100,10和5 k Pa·s。开展不同黏性岩石的动态巴西盘试验,测得砂岩和人造岩心试样的动态抗拉强度随着加载率的增大而增大,表现出一定的加载率相关性;证明了黏性对岩石强度加载率效应的影响,但两者并非正相关;在较小的加载速率下,岩石黏性导致试样中传播的应力波能量衰减,在巴西盘中心点起裂的裂纹沿加载直径方向扩展但是不足以使试样破坏成两半,从而验证了巴西盘裂纹起裂位置。

Experimental investigation to effect of viscosity and loading rate on tensile strength of sandstone

The impact test and dynamic Brazilian test using the pendulum hammer driven SHPB apparatus were conducted to measure the viscosity coefficient of sandstone and artificial rock and to examine the loading rate effect. The viscosity coefficients of sandstone and artificial rock A and B are 100，10 and 5 kPa?s respectively and were determined with the combined method of experiment and numerical simulation. The dynamic tensile strength of the sandstone and artificial rock samples increase with the loading rate，showing the strong strain-rate dependency. The influence of viscosity on loading rate effect of dynamic tensile strength is validated，but they are not positive correlated. The energy of stress wave propagation in the sample attenuates with the sandstone viscosity under the low loading rate. So the crack initiates at the center of Brazilian sample and propagates along the loading diameter，but the sample is not separated into two halves. The position of crack initiation at the center of sample is thus validated.