针对有限差分法及有限元法等连续介质数值方法无法模拟砂卵石地层的离散介质属性的问题，基于块体离散元方法，建立离散元模型模拟盾构穿越砂卵石地层掘进过程，研究盾构掘进过程中砂卵石地层中块体或颗粒间结构面的位移以及围岩与管片变形；然后将砂卵石地层等效为连续介质，建立有限差分模型模拟盾构掘进过程，对比离散元模型与有限差分模型数值结果之间的差异。结果表明：离散元模型中结构面正法向位移超过0.1mm的区域主要集中在仰拱处，结构面负法向位移超过0.1mm的区域位于两侧拱腰处，结构面切向位移超过0.4mm的区域主要集中在仰拱处；离散元模型中围岩和管片的变形均大于有限差分模型，所以采用离散元方法对砂卵石地层中隧道及管片设计方案进行验证更加安全、合理。

To address problems of numerical methods for continuous medium such as finite difference method and finite element method finite difference method and finite element method being unable to simulate the discrete medium characteristic of sandy cobble stratum, based on block-based Discrete Element Method, discrete element model is built to simulate the process of shield tunnelling through sandy cobble stratum, the displacement of joint plane and deformation of surrounding rock and liner is studied; and finite difference model, where sandy cobble stratum is transformed into equivalent continuous medium, is built to simulate the process of shield tunnelling, for the purpose of comparing the differences in numerical results between the discrete element model and the finite difference model. The results show that, in the discrete element model, the area where the positive normal displacement of the joints exceeds 0.1mm is mainly concentrated at the inverted arch, the area where the negative normal displacement of the joints exceeds 0.1mm is located at the hance, and the area where the shear displacement of the joints exceeds 0.4mm is mainly concentrated at the inverted arch. The joint shear displacement caused by the disturbance of shield tunnelling is greater than the joint normal displacement, so the potential failure mode of the surrounding rock in the sandy cobble stratum may be shear failure. The deformation of surrounding rock and liner in the discrete element model is greater than that in the finite difference model, so utilizing Discrete Element Method to verify the design of tunnel and liner is more secure and reasonable.

教育部协同育人项目22（CXY-007）