基于块体离散元法的盾构掘进围岩与管片变形模拟研究

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的掘进过程，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；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，并且对比离散元模型与有限差分模型计算结果之间的差异。结果表明：离散元模型中结构面正法向位移超过 0.1 mm的区域主要集中在仰拱处，结构面负法向位移超过 0.1 mm 的区域位于两侧拱腰处，结构面切向位移超过 0.4 mm的区域主要集中在仰拱处；对于围岩和管片的变形，离散元法的计算结果均大于有限差分法，因此采用离散元方法对砂卵石地层中隧道及管片的设计方案进行验证相对更加安全、合理。

Simulation Study of Shield Tunneling Based on the Block-Based DiscreteElement Method and Deformation of the Surrounding Rock and Liner

This study addresses problems of numerical methods for continuous media, such as the finite difference and finiteelement methods to simulate the discrete medium characteristics of a sandy cobble stratum. Based on the block-based discreteelement method, a discrete element model is built to simulate the process of shield tunneling through a sandy cobble stratum,and the displacement of joints and deformation of the surrounding rock and liner is studied. A finite difference model, in whicha sandy cobble stratum is transformed into an equivalent continuous medium, is built to simulate the process of shield tunneling,and to compare the differences in simulation results between the discrete element model and the finite difference model. Theresults show that, in the discrete element model, the area at which the positive normal displacement of the joints exceeds 0.1 mmis primarily concentrated at the inverted arch, the area at which the negative normal displacement of the joints exceeds 0.1 mmis located at the hance, and the area at which the shear displacement of the joints exceeds 0.4 mm is primarily concentrated atthe inverted arch. The simulation results of the discrete element method are greater than those of the finite difference methodwith respect to the deformation of the surrounding rock and liner; therefore, utilizing the discrete element method to verify thedesign of the tunnel and liner is relatively more secure and reasonable.