基于D-P系列屈服准则的隧道开挖效应研究

为选用合适的D-P准则以获取理想的计算结果，对不同D-P系列屈服准则进行比较系统及深入的研究，论证准则转换强度折减的本质。以梅大高速圣人山隧道为背景，采用现场监测和数值模拟相结合的方法，分析各分区岩体稳定性状态随开挖过程的演化规律。结果表明： 1）隧道拱底区应力调整最为强烈，拱顶次之，侧壁最弱； 拱顶区围岩经历了压剪、拉剪、压剪循环破坏过程； 侧壁区围岩以压剪破坏为主，其压剪松动区形态呈“侧耳形”； 拱底区各点在掌子面通过目标截面后一直处于三向受拉状态。2）选用不同的屈服准则对θσ计算结果影响不大，但对应力计算结果影响较大，计算中同时考虑围岩关键部位受力状态进而采取合适的D-P准则很有必要。

A Study on Tunnel Excavation Effect Based on Drucker-Prager Yield Criteria

In order to establish the essence of the strength reduction theory,the authors compare various Drucker-Prager yield criteria and select a formula that best serves their needs.Taking the construction of Shengrenshan tunnel as an example,the authors adopt site monitoring together with 3D numerical simulations to analyze the stability rules of rock mass in different zones.The study shows that：1） The unloading effect of the excavation at the invert is more evident than that at the crown tunnel; The surrounding rock at the crown goes through a compressing-shearing,tensioning-shearing,and compressing-shearing circulating failure process; The failure of the surrounding rock at the sidewall takes a ＂compressing-shearing＂ pattern,with a loosening zone occurring in the shape of an ＂ear＂ ; The surrounding rock at the invert continues to be in a tri-directional tensioning state as the tunnel face passes the target section.2） The selection of different Drucker-Prager yield criteria in the numerical simulation has little effect on the calculation results of Lode angle,but it has great effect on the calculation results of stress.It is necessary to take the stress state of the surrounding rock into consideration so that a suitable Drucker-Prager yield criterion can be adopted.