不同饱水度下红砂岩动静态力学试验

基于φ100 mm SHPB试验平台和液压伺服试验机,对4种饱水度下红砂岩进行动、静态压缩试验,探究了饱水度对岩石强度、峰值应变、峰值模量及应变率效应的影响规律,并从细观角度对实验结论进行分析,得出:饱水度对岩石强度的影响存在临界值S_l,饱水度小于临界值S_l时,强度随饱水度的增加而线性降低,当饱水度达到S_l后,随着饱水度的增大,岩石强度的变化幅度非常小;峰值应变在饱水度为0.42时出现极小值,动态试验条件下的峰值应变对饱水度更为敏感;峰值模量随饱水度的增大而线性减小;从细观角度探究饱水度对峰值模量的影响,应主要把握3个关键参数:矿物颗粒和粒间胶结物的受力能力、协调变形能力以及孔隙发育程度;随着饱水度的增大,岩石力学性质的应变率效应越来越明显。其中,饱水度对岩石强度应变率效应因子影响最大,对峰值应变应变率效应因子影响次之,对峰值模量应变率效应因子影响最小。

A Dynamic / Static Experiment Research on the Red-Sandstone Mechanical Property under Different Saturated Degree

Based on the hydraulic servo testing machine and the split Hopkinson pressure bar (SHPB) with a diameter of 100 mm, the dynamic / static experiment compression tests of red-sandstone with different saturated degree of water are tested, the mechanical properties of the rock is studied, and the experimental conclusion from the perspective is analyzed. The conclusion is that there is a critical saturated degree Sl for the impact on rock strength. when the saturated degree is less than Sl , the intensity linearly decreases with the increase of saturated degree. when the saturated degree is larger than Sl, the change range of rock strength is very small along with the rising of the satisfied degree. The minimal peak strain appears at the saturated degree of 0.42 and the peak strain under the condition of dynamic test is more sensitive to the saturated degree. The Peak modulus linearly decreases with the increase of saturated degree. From a judgment upon the influence of the saturated degree on the peak modulus from the Microcosmic view, three key parameters should be seized, i.e. loading ability of mineral grains and cement between them, coordinate ability to deformation of them and degree of pore development. Along with the rising of the saturated degree of water, the strain rate effect of rock mechanics properties have become more and more obvious. Among them, the saturated degree of water has the greatest influence on the strain rate effect of rock strength and the smallest effect on the strain rate effect of rock modulus.