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水和加载条件对岩石材料的强度有很大的影响,但高应变率下饱水岩石的动态特性研究仍十分缺乏。通过对干燥和饱水砂岩进行压缩试验,发现:干燥和饱水砂岩的动态压缩强度都随着应变率的增加而增大,且饱水岩石表现出更强的率相关性。引入干燥岩石强度与饱水岩石强度的比值(水影响因子WAF)来描述不同应变率下水对岩石压缩强度的影响。在静态压缩条件下WAF约为1.38,随着应变率的增加WAF不断减小。当应变率达到190 s~(-1)时,WAF减小至0.98,表明高应力率时饱水岩石的压缩强度可以大于干燥岩石的压缩强度。进而,基于滑移裂纹模型,讨论了水和应变率对岩石特性的双重影响,为实验结果提供了较好解释。
Water and loading conditions have a great influence on the strength of rock materials, but the dynamic characteristics of saturated rock under high strain rate are still lacking. Compressive tests on dry and saturated sandstone show that the dynamic compressive strength of both dry and saturated sandstone increases with the increase of strain rate, and the saturated rock shows a stronger rate of correlation. The ratio of dry rock strength to saturated rock strength (water impact factor WAF) was introduced to describe the effect of water at different strain rates on compressive strength of rock. The WAF under static compression is about 1.38, and WAF decreases with the increase of strain rate. When the strain rate reaches 190 s -1, the WAF decreases to 0.98, indicating that the compressive strength of saturated water rock can be higher than that of dry rock under high stress rate. Furthermore, based on the slip crack model, the dual influence of water and strain rate on the rock properties is discussed, which provides a good explanation for the experimental results.