西宝高铁兴平段路基组合桩地基处理技术

Technology of subgrade's foundation treatment by combined piles in Xinping section of Xi'an-Baoji high speed railway

西安至宝鸡高铁兴平段路基位于关中平原西部渭河二级阶地上,地层上部为湿陷性黄土及饱和黄土,下部为砂层及圆砾土层,地下水位埋深较浅,路堤最大填方高度8 m,路基工后沉降难以控制。经综合方案比选,地基采用组合桩处理。本文详细地阐述了组合桩的设计计算方法,通过沉降观测、动态检测及运营实践证明,组合桩地基处理措施有效控制了路基工后沉降,满足无砟轨道铺设要求,使用效果良好。与传统单一桩型复合地基处理效果相比,组合桩具有节约投资、提高地基承载力、有效控制工后沉降等优势。

The Xingping section on Xi＆#39;an-Baoji high speed railway,laying on the second terrace of western Weihe plateau,faces the challenge of subgrade settlement,as the collapsible loess and saturated loess compose the upper layer,while sand and gravel soil form the lower layer. T he shallow groundwater depth and a maximum filling height of 8 m further pile on the treatment task. T he paper compares the available schemes and proposes the combined pile foundation as a preferable solution. It entails the designing concept and calculation approach,and on this basis,carries out settlement observation,dynamic detection and operation experiment to prove its validity. T he results show that the scheme effectively controls the settlement,creating an enabling environment for ballastless-track pavement. Compared with widely-applied single-pile foundation,this cost-effective solution helps enhance the bearing capacity of the foundation and brings settlement under control.