摘要:研究目的:针对饱和黄土地区浅埋暗挖法隧道下穿国铁站场岔区工程遇到的铁路运营及隧道施工安全 问题，通过工程类比与数值模拟分析手段，初步研究既有铁路道岔区沉降控制标准、地层改良加固、隧道支护 措施及施工方法、道岔区轨道加固等诸多关键问题，为工程建设提供技术支撑。 研究结论：1)暗挖隧道下穿国铁站场道岔区地表沉降控制标准综合考虑可定为15 mm,铁路路面允许 沉降速率标准为5 mrn/d,对于非道岔区可适当降低标准；（2)道岔区段轨道加固方式采取分区分段的原则， 非道岔区采用D梁加固形式，道岔区采用纵横梁加固体系；（3 )通过全断面深孔注浆改良地层、配合CRD法 施工及大管棚超前支护体系，可有效抑制掌子面前方地层的预收敛变形，有效控制地层沉降变形，确保饱和黄 土地质隧道下穿道岔区安全；4)本研究成果可为黄土地层隧道下穿铁路道岔区的施工提供借鉴与参考。

Abstract ： Research purposes ： According to the safety problems of railway operation and tunnel construction occurred to the engineering passing turnout area of national railway station yard in the tunnel of undercutting with shallow overburden in the saturated loess area， by means of engineering analogy and numerical simulation analysis method， this paper researched a number of key issues， such as the settlement control criterion of turnout area of existing railway， ground improving and strengthening，supporting measure and construction method of tunnel and track strengthening of turnout area，to provide the technical support for the engineering construction. Research conclusions:( 1) The ground settlement control criterion of metro turnout area of mining tunnel under - passing national railway station yard can be considered as 15 mm， and the allowable settlement rate criterion of railway pavement can be considered as 5 mm^d, and then in non - turnout area, the criterion can be appropriately reduced. (2)The way to strengthen track of turnout area takes the principle of partition segment， non - turnout area using the form of strengthening D beams, turnout area using the system of strengthening vertical and horizontal beams. (3) With the ground improved by deep hole grouting in full section， the CRD construction method and the advanced support system of big pipe shed， the pre - convergence deformation of strata in front of tunnel face can be effectively suppressed， the settlement deformation of strata can be effectively controlled， and the safety of passing turnout area in saturated loess tunnel can be ensured. (4) The research results can provide references for the construction of the tunnel under - passing railway turnout area in loess area.