天津地区盾构施工对地层沉降的影响

以天津地铁2号线某盾构隧道施工段为背景，运用有限元模拟并结合现场监测资料，研究盾构施工对地层沉降的影响．结果表明：地表任一断面在盾构施工过程中都要经历一个随距开挖面相对位置不同而不断变化的沉降过程；同一断面不同深度处土层的沉降量及沉降影响范围不同，深层土体受施工扰动响应较地表更为敏感；通常情况下浅表层与深层土体沉降趋势一致，但由于城市地表硬壳层的存在，会导致监测数据较实际沉降值偏小，实际工程中应重视这种现象．

Influence of Shield Construction on Strata Subsidence in Tianjin Area

Against the background of a shield tunnel project of Tianjin Metro Line 2, this paper uses finite element simulation analysis and the site monitoring data to study the influence of shield construction on stratum subsidence. The study result shoves that the surface at any cross section in the shie｜d construction process is goir~g to have a changing settlement process by different relative position to the excavation face. The subsidence and its scope of the same cross section at different depths of soil layers are different, and the response of the deep soil to the construction disturbance is more sensitive than that of the surface. Normally, the surface subsidence is consistent with the trend of deep soil settlement, but because of the existence of urban surface crust layer, monitoring data are snaaller than the actual value of subsidence. Therefore, importance should be attached to this phenomenon in the real projects.