大功率振冲碎石桩处理液化地基应用研究

Application of High Power Vibroflotation Gravel Pile in the Treatment of Liquefied Foundation

北京某地铁车辆段占地面积约20 hm^(2),场地20 m深度范围内的饱和粉细砂(2)5层为地震液化层,该液化层厚度约为5 m,液化等级为轻微—中等(局部为严重)。在轨道交通工程中首次应用大功率(100 kW)、疏排振冲碎石桩对液化地基进行处理,检测结果及施工实践表明,该方法既满足地基液化处理设计要求,同时也为后期灌注桩原位施工创造了条件。此外,该工程应用大功率振冲碎石桩与CFG桩组合地基处理方式解决了地基液化和轨道路基工后沉降问题。

A subway depot in Beijing covers an area of about 20 hectares.The(2)5 layers of saturated silty fine sand within 20m depth of the site will produce liquefaction.The liquefaction grade is slight to medium(locally serious),and the thickness of liquefiable layer is 5 m.In the rail transit project,the high-power 100 kW vibroflotation gravel pile is used to treat the liquefied foundation for the first time.The test results show that the vibroflotation gravel pile with large pile spacing not only meets the design requirements of foundation liquefaction treatment,but also creates conditions for the in-situ construction of cast-in-place pile in the later stage.At the same time,the combination of high-power vibroflotation gravel pile and CFG pile foundation treatment is applied to the site,which solves the problems of foundation liquefaction and post construction settlement of track subgrade.