摘要:研究目的:为研究宁波地区地铁盾构下穿铁路路基的变形控制，本文首先基于宁波典型土层，通过数值 模拟与P；k经验公式，得出盾构施工引起的各土层沉降槽宽度系数参考值;其次以盾构下穿甬台温铁路为研 究背景，通过三维数值模拟的对比分析，研究盾构穿越完全加固区、部分加固区以及非加固区的路基沉降变形 规律。研究结论:(1)宁波典型土层可归纳为淤泥质土、黏性土、粉土及砂性土三类，盾构施工扰动引起的！值 及沉降槽宽度在三类土中依次减小，最大沉降值依次增加；（2)通过线形回归拟合，首次提出了土层扰动的初 始敏感因子和深度敏感因子，随着区间埋深的增加，初始敏感因子作用逐渐减弱，深度敏感因子的作用逐渐增 强，当埋深足够大时，地面变形趋于一致;（3 )盾构下穿既有加固的铁路路基时，应避免穿越半加固区，在完全 加固区与非加固区，盾构下穿引起的路基变形均随埋深的增加逐渐减小，但非加固区内沉降曲线趋于平缓； (4 )本研究成果对软土地区盾构下穿铁路的方案优化和安全施工具有借鉴意义。

Abstract:Research purposes: Based on the numerical simulation and Peck - empirical formula，it is concluded that the coefficient reference value of soil settlement trough caused by shield construction. For analyzing the settlement control of subway shield undercrossing railway subgrade， the engineering of shield pass through Ningbo - Taizhou - Wenzhou railway is considered. By the method of three - dimensional numerical simulation，the settlement discipline are put forward when shield travel across the subgrade reinforced area，half - reinforced area and unreinforced area. It can provide theoretical reference for the similar projects in this region. Research conclusions:( 1)The soil of Ningbo area can be summarized as silt soil，clay，silty and sand soil. The value of K and the width of settlement trough are decreasing in turn caused by shield construction disturbance， but the maximum settlement value is creasing in turn. (2 ) By the way of linear regression fit，the initial sensitive factor and the depth sensitive factor are first defined. With the increasing depth of the shield，the former effects gradually weakened， and the latter effects gradually increased. When the depth is sufficiently large，the deformation tends to be consistent. The shield should avoid crossing half - reinforced area，if tlie subgrade has been reinforced. In the area of reinforced part or unreinforced part，the subgrade deformation，that coming from the disturbance of shield construction，decreases with increasing depth. The settlement curve changes slowly in unreinforced part of the reinforced subgrade. (4) This paper provides a theoretical basis for the optimization of subway shield undercrossing railway subgrade and safety shield construction in soft soil area, with a strong reference for similar projects.