软土地质条件下盾构穿越高速铁路对路基工后沉降的影响

依托南京地铁4号线一期工程徐金区间隧道下穿京沪高铁联络线及仙宁铁路项目，运用理论分析与现场变形观测相结合的方法，分析铁路路基在盾构隧道施工期及工后期的沉降规律。研究表明:Peck沉降理论计算的地表沉降极大值发生在两个隧道中心对应的地表处，随地层损失率的增加而增加，具对称性；与一般黏性土或者砂性土不同，软土地质条件下盾构隧道穿越高速铁路路基引起的沉降量主要发生在工后，沉降比率最大达75.64 %，沉降稳定时间长、沉降槽的深度和宽度较大；实际观测的沉降值远大于理论计算值，受施工影响沉降槽曲线呈现出非对称性。研究成果可为软土地质条件下盾构隧道掘进变形控制以及运营期高速铁路沉降变形控制提供参考。

Influence of Shield under-crossing High-speed Railway on Post-construction Settlement of Subgrade in the Condition of Soft Clay

In relation to the project of Xu—Jin interzone tunnel of Nanjing Metro Line 4 (phase I) under-crossing Beijing—Shanghai High-speed Railway connections and Xianning Line, the settlement laws of railway subgrade during and after the shield tunnel construction were analyzed by theoretical analysis with field deformation observation. The results show that, the maximum value of ground surface settlement calculated by Peck settlement theory occurs at the ground surface where corresponds to the centers of the two tunnels, and will increase with the increase of ground loss rate, being of symmetry property; different from general cohesive soil or sandy soil, the settlement caused by shield tunnel crossing high-speed railway subgrade in the geological condition of soft soil, mainly occurs after the construction, and the post-construction settlement reaches the proportion up to 75.64 % with long settling time, large depth and width of settlement trough; the settlement observed is far more than the calculated value, and affected by the construction, the curve of settlement trough shows asymmetry. The study achievements can provide reference and experience both in the shield tunneling deformation control in the condition of soft clay and in the settlement deformation control of high-speed railway in operation.