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隧道围岩非线性体积膨胀影响施工安全,如何正确评价隧道围岩塑性区域内扩容机制非常重要。多数研究从理论上推导深埋圆形隧洞应变软化围岩应力-应变场时仅采用恒定或线性变化剪胀模型,针对此不足,提出了一种基于有限差分法的分析方法,能够合理地考虑围岩非线性剪胀效应及其应变软化特性。利用已有的研究成果,验证了该方法的合理性,并进一步探讨了不同质量石灰岩与支护压力下剪胀系数在围岩塑性区域内的影响因素,比较了恒定与非线性变化剪胀模型下围岩变形的不同。结果表明:对于地质强度指标(GSI)较小、质量较差的岩体,塑性区域内主要由围压控制剪胀效应程度;恒定与非线性变化剪胀模型下围岩洞壁变形差别显著。
Non-linear expansion of tunnel surrounding rock affects construction safety. It is very important to evaluate correctly the mechanism of expansion in plastic zone of surrounding rock of tunnel. Most studies have theoretically derived only the constant or linearly varying dilatancy model for the strain-softening rock surrounding the deep circular tunnel. In view of this problem, a method based on the finite difference method is proposed, which can be reasonably considered Nonlinear dilatancy of surrounding rock and its strain softening behavior. Using the existing research results, the rationality of the method is verified, and the influencing factors of dilatancy coefficient in the plastic zone of surrounding rock under different mass limestone and supporting pressure are further discussed. The variation of constant and nonlinear dilatancy model Under the rock deformation of the different. The results show that for the rock mass with small GSI and poor quality, the dilatancy effect is mainly controlled by the confining pressure in the plastic zone. The deformation of the wall of the surrounding rock is obviously different under the constant and non-linear dilatancy models.