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本文根据晶屑凝灰岩、石英砂岩、粉砂岩等在不同应变率下的压缩或拉伸试验结果,并结合国外的大量试验资料,得出岩石破坏强度发生显著变化的应变率范围ε_d;应变率小于ε_d时,随着应变率的变化,岩石强度无明显变化;应变率达到或超过ε_d时,岩石强度就有显著增长,对此用破裂传播速度作了理论分析和解释。另外根据岩石破坏前变形随应变率增大或减小的现象,提出了不同岩石具有不同的临界应变率。用该临界应变率可以确定岩石破坏后区的变形是随荷载的减小而呈增大或减小的变化趋势,并对此观象用破坏能的概念进行了探讨。本文还研究了软岩、硬岩对应变率的敏感度;并指出增大试件围压会使试件的应变率敏感度减弱,也就是说使试件趋于“硬化”。以上结论及理论分析不仅在理论上具有重要的意义,在岩石工程中也有实用意义。
In this paper, according to the results of compression or tensile tests at different strain rates, such as crystal tuff, quartz sandstone and siltstone, combined with a large amount of experimental data from abroad, the strain rate range ε_d at which the rock failure strength significantly changes is obtained; the strain rate is less than In the case of ε_d, the rock strength does not change significantly with the change of the strain rate. When the strain rate reaches or exceeds ε_d, the rock strength increases significantly. The theoretical analysis and explanation of the crack propagation velocity are made. In addition, according to the phenomenon that the deformation before rock failure increases or decreases with the strain rate, it is proposed that different rocks have different critical strain rates. With this critical strain rate, it can be determined that the deformation of the post-failure zone of rock is increasing or decreasing with the decrease of the load, and the concept of the destruction energy for this observation is discussed. This paper also studies the sensitivity of the corresponding variability of soft rock and hard rock, and points out that increasing the confining pressure of the specimen will weaken the strain rate sensitivity of the specimen, which means that the specimen tends to “harden”. The above conclusions and theoretical analysis not only have important theoretical significance, but also have practical significance in rock engineering.