桂花屋基特大桥临近既有线基坑支护设计及分析

On the Support Design for and Analysis of the Foundation Pit for the Guihuawuji Mega Bridge near an Existing Railway

桂花屋基特大桥临近运营的渝黔铁路,其8#承台基坑距离既有线最近,在充分考虑既有铁路线安全的前提下,分析了地质、水文条件、造价和工期因素,最终确定采用C-T型锁扣钢管桩的大刚度支护结构,并且设计了围囹体系。根据施工工况,采用理正软件的单元法对防护桩进行计算分析,并采用midas软件对支撑体系进行了计算。计算结果表明:各个施工工况下,钢管桩和支撑体系的强度和刚度均满足要求,施工引起的周边沉降也满足铁路部门的限值要求,并且与实测沉降值基本吻合。这可为临近既有线的基坑支护设计提供有益的参考。

As the Guihuawuji Mega Bridge is close to the existing Yu-Qian Railway in operation,and the 8 杯 foundation pit of the cap is the closest to the existing railwayupon the basis of fully considering the safety of the existing railwayand analyzing the geological and hydrogeological conditions, costs, the construction duration and other factors, the C-T-type lock steel-tube pile retaining structure with great stiffness is finally chosen with the waling system designed. In the light of the construction condi-tionsthe protection piles are calculated and analyzed by means of the Lizheng software with the Midas software used for the calculation of the supporting system. The results of the calculation show that under all the construction conditions both the strength and stiffness of the steel-tube pile and the support system meet the requirements and the surrounding settlement is al-so up to the limit requirements of railway departments. Besides, the real monitored values of settlement are found consistent with the designed values of settlement. This paper may provide a useful reference for the design of supports for other foundation pits near existing railways.