以某紧邻既有铁路线的基坑工程为依托，基于现场实测数据，分析了路基与基坑的变形规律、沉降原因和控制措施。结果表明，受列车荷载与渗漏水影响，路基沉降在坑底旋喷加固和施工冠梁、混凝土撑期间迅速增加，形成了长约50 m、最大沉降95 mm的沉降槽，60%以上的路基在该阶段的沉降增量占阶段累计沉降的70%以上，而地表沉降多小于20 mm，约为开挖深度的2.4‰；路基沉降槽处坑外横断面地表沉降呈“凹槽形”，在路基处沉降最大。在坡顶进行双液注浆能够控制地表与路基沉降，减少后续开挖施工对路基的影响，但注浆施工易导致边坡变形突变，尤其是向坑内的水平位移，不利于边坡稳定和铁路安全。

Deformation of subgrade and pit observed during construction of foundation pit engineering near a railway are presented. The deformation and control measures are analyzed. The settlement of surface ground and subgrade increase linearly over time during slope excavation, which is up to 12 mm after the slope excavation is completed. Affected by the train load and water leakage, the subgrade settlements increase rapidly during the construction of jet-grouting reinforcement of foundation pit bottom, top beam and concrete strut; and a nearly 50 meters long settlement tank with maximum settlement 95 mm is observed. It is also found that over 60% of subgrade subsidence increment during the construction of aforementioned stages accounts for more than 70% of cumulative settlement. Most of the surface settlement is less than 20 mm, 2.4‰ of excavation depth. The shape of the ground surface settlement profile within the region of subgrade settlement tank is concave type and the maximum settlement occurs at the subgrade. Two fluid grouting at slope top can effectively control the surface and subgrade settlement and reduce the impacts of subsequent excavation on subgrade. But the grouting construction may cause displacement mutation of slope, especially the lateral displacement towards to the pit, which is harmful to slope stability and railway safety.