Characteristics of strength of rocks under different unloading rates
Characteristics of strength of rocks under different unloading rates
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发表时间：
2010
影响因子：
1.5
通讯作者：
Yuan-gang Zhang
中科院分区：
文献类型：
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作者：
Yuan-gang Zhang
研究卸载条件下岩石的强度特性对于地下工程的安全评价具有重要意义。影响卸载试验强度的因素有岩性、初始卸载应力、卸载应力路径和卸载速率等。其中，本文重点关注卸载速率。提出屈服逼近率（YAR）来表示加载和卸载条件下的应力变化率。 一般三轴试验中，当卸载围压率为加载轴向应力率的0.2-0.3时，加载和卸载条件下的强度几乎相等。EPCA2D（弹塑性元胞自动机）模拟和大理石卸载试验表明，随着卸载率的增加，岩石的强度会增加，并且当卸载率为0.2-0.3时，加载和卸载条件下的强度相等。 由此可以得出，如果给定YAR且初始卸载应力处于弹性状态，则卸载应力路径对强度影响很小。
The study of strength characteristics of rocks under unloading condition is of very importance to the safety evaluation of the underground engineering.There are many factors affecting the strength in unloading test,such as lithology,initial unloading stress,unloading stress path and unloading rate,etc.Among these factors,the unloading rate is concerned in this study.Yield approach rate(YAR) is proposed to denote the stress varying rate under loading and unloading conditions.The YAR under loading and unloading conditions is almost equal when the unloading confining pressure rate is 0.2-0.3 of the loading axial stress rate in general triaxial tests.The simulation by EPCA2D(Elasto-Plastic Cellular Automaton) and the unloading test on marble indicate that the strength of the rock will increase as the unloading rate is higher and the strength under loading and unloading conditions is equal when the unloading rate is 0.2-0.3 of the loading rate.Then the conclusion can be drawn that if the YAR is given and the initial unloading stress is in the elastic state,the unloading stress path has little influence on the strength.