临界状态围压在岩石强度准则改进中的应用

岩石强度准则一般是通过低围压岩石力学试验提出，这些准则在高围压下得到的岩石强度比实测强度偏大。为解决这一问题，提出岩石临界状态围压的概念，并推导得到当围压达到临界状态围压时，偏应力为常数，临界断裂角为45°，以广泛使用的Mohr-Coulomb和Hoek-Brown准则为例，将其应用到准则的改进中。通过完整岩石三轴试验数据对改进准则的准确性和适用性进行验证，分析结果表明：应用岩石临界状态围压改进的强度准则参数对围压变化的敏感度较低，其不仅保持了原准则在低围压时评估岩石强度的一致性、准确性，而且在高围压时其评估的强度与试验强度较一致，解决了高应力条件下原强度准则高估岩石强度的问题。

Application of critical state confining pressure to rock strength criteria modification

Generally, rock strength criteria are obtained by the triaxial compression tests at the low confining pressure. However, the strength in these criteria tends to be higher than experimental data at the high confining pressure. To overcome this deviation, we propose a concept of rock critical state confining pressure. It can be deduced that deviator stress is constant and critical rupture angle is 45 degrees at critical state using this concept. It is then introduced to modify Mohr-Coulomb and Hoek-Brown strength criteria. The accuracy and applicability of these two modified criteria are verified by a series of triaxial experimental tests. It is noted that the parameters in modified criteria have lower sensitivity to the confining pressure than those in the original criteria. The modified criteria can not only maintain the consistency and accuracy in strength assessment at the low confining pressure, but also assess the consistency of experimental strength at high confining pressure. Thus, the modified criteria can be used to accurately estimate the strength of rock at the high confining pressure.