Soil layer parameter settings.

The deformation of pile caused by tunnel excavation will weaken the bearing capacity of the foundation. In order to investigate the deformation response of pile induced by the construction of three-hole small spacing tunnel, the DEM-FDM (discrete element method and finite difference method) coupling numerical simulation method were used to simulate the deformation process of pile during tunnel excavation. This paper probed into the deformation response of pile by three factors: the length of pile, the pile-tunnel spacing, and the three-hole tunnel construction. The results showed that, as the pile-tunnel spacing decreases, the incremental horizontal displacement of the pile top became more significant when the three-hole tunnel was excavated. The excavation resulting in four zones of horizontal displacement concentration. The prominent locations were mainly concentrated on both sides of the tunnel and the ground directly above the tunnel. The research findings of this study can provide insights and references for the design and construction of shield tunneling under passing piles.

隧道开挖引发的桩基变形会削弱地基的承载能力。为探究三孔小净距隧道施工诱发的桩基变形响应，本文采用离散元法与有限差分法耦合（DEM-FDM，Discrete Element Method and Finite Difference Method）数值模拟方法，对隧道开挖过程中的桩基变形历程进行模拟。本文从桩基长度、桩隧间距以及三孔隧道施工三个影响因素入手，对桩基变形响应展开研究。研究结果表明，在三孔隧道开挖工况下，随着桩隧间距减小，桩顶水平位移增量愈发显著。本次开挖形成了四个水平位移集中区，其主要分布位置集中于隧道两侧及隧道正上方地表。本研究成果可为下穿既有桩基的盾构隧道设计与施工提供有益参考与借鉴思路。