中文摘要：

在分析中主应力对隧道围岩强度影响的基础上，采用FLAC3。有限差分元软件，建立考虑中主应力的岩体强度准则本构模型，并同摩尔库伦准则相比较，研究考虑中主应力后对隧道围岩稳定性的影响。结果表明：考虑中主应力后，计算得到的岩体强度较不考虑时显著增加，当中主应力大于等于岩体抗压强度时，围岩强度提高75％-200％；若围岩服从摩尔库伦准则，则在一定数值范围内，中主应力不影响隧道中围岩的应力分布，且对拱顶沉降及塑性区也几乎没有影响；若围岩服从考虑中主应力的岩体强度准则，则随着中主应力的逐渐增大，围岩强度逐渐增大，拱顶沉降、开挖扰动范围和塑性区半径均逐渐减小。因此，在隧道侧向应力较大时，采用考虑中主应力的岩体强度准则进行数值模拟，更能准确地反应围岩的稳定性。

英文摘要：

Based on the analysis of the influence of intermediate principal stress on the strength of surrounding rock, with the finite difference software FLAC3D, the constitutive model for the strength criteria of rock mass was constructed considering the influence of intermediate principal stress, which was compared with Mohr-Coulomb criteria, and the influence of intermediate principal stress on the stability of tunnel surrounding rock was studied. The results showed that, the calculated strength of rock mass after considering intermediate principal stress increased obviously by the comparison with the condition without considering intermediate principal stress. The strength of rock mass increased by 75~ ~200% when the intermediate principal stress was greater than or equal to the compressive strength of rock mass. If the results of surrounding rock obeyed the Mohr-Coulomb failure criterion, in a certain number range, the intermediate principal stress had no influence on the stress distribution of tunnel surrounding rock and almost no influence on crown settlement and plastic zone as well. If the results of the surrounding rock obeyed the strength criteria of rock mass considering intermediate principal stress, the strength of surrounding rock increased gradually with the gradual increase of intermediate principal stress, but the crown settlement, disturbance range due to excavation and the radius of plastic zone all decreased gradually. Thus, when the lateral stress of tunnel is larger, to perform numerical simulation using the strength criteria of rock mass considering intermediate principal stress can reflect more accurately the stability of surrounding rock.