Abstract: Most of urban subway tunnel excavations often pass underneath and alongside buildings or structures. In order to ensure the smooth excavation of tunnels, it is necessary to study the force and deformation of the existing structures. Based on the shield construction passing alongside a viaduct in a section of Xian Metro Line 4, the force and deformation caused by the shield passing alongside the viaduct pier was analyzed by means of numerical simulation and on-site monitoring; and the settlement value calculated by numerical calculation was compared with the actual monitoring value. The results show that: the size of earth pressure has great influence on the surface subsidence for the shield construction in the sand layer environment, and the pier has certain restraining effect on the surface settlement. The settlement of the existing structure can be effectively reduced by proper placement of pile foundation in the shield construction. The above conclusions can provide reference for the risk sources of similar shield passing alongside.

Key words: geotechnical engineering, EPBS, close distance, passing alongside, viaduct, force and deformation

摘要： 城市地铁隧道开挖往往会下穿、侧穿建(构)筑物。为保证隧道顺利开挖，有必要对既有结构进行受力与变形研究。以西安地铁四号线某区间盾构侧穿高架桥施工为例，通过数值模拟和实时监测分析盾构侧穿高架桥桩所引起的受力与变形，并将数值计算得出的沉降值与实际监测值进行对比。结果表明：盾构在砂层环境下，土压力的大小对地表沉降的影响较大；桥墩对地表沉降有一定的约束作用，盾构施工中在合适的地方布置桩基，能有效的减小既有结构的沉降。研究结果可供类似盾构侧穿风险源参考。

关键词: 岩土工程, 土压平衡盾构, 近距离, 侧穿, 高架桥, 受力与变形