真空预压联合搅拌桩在有轨电车软基加固中的应用

有轨电车以其绿色环保的运营方式正在引领中国交通行业向可持续方向发展。针对南京河西地区软土地基的结构特点和工程特性,提出了真空预压联合搅拌桩软基加固方法,结合施工期表层沉降、分层沉降、水平位移和孔压及运营期累计沉降监测结果,分析了该软基处理方法的加固效果。研究结果表明:在抽真空过程中,孔隙水压力随着深度的增加而逐渐减小;水平位移和分层沉降变化率均逐渐减小;表层总沉降量在抽真空2个月后趋于稳定,表明软土层接近完成固结;施工期的表层累计沉降量为440 mm;运营后半年累计沉降为4.2 mm,预测运营10 a后累计沉降约为9.8 mm,远低于设计警戒值。说明真空预压联合搅拌桩的方法可以有效加固有轨电车软土地基。

Application of vacuum preloading combining mixing pile method in treatment of tram foundation

Due to the green and environmental protection operation mode, the tram is leading the transportation industry into sustainable development in China. According to the structural characteristics and engineering properties of soft soil foundation in Nanjing, a vacuum preloading combining mixing pile foundation treatment method is proposed. Based on the monitoring results of surface settlement, layered settlement, horizontal displacement and pore pressure in construction period and cumulative settlement in operation period, the improvement effect of the proposed method as analyzed. It is shown that the pore water pressure gradually decreases with the increase of the depth. The horizontal displacement and layered settlement all decrease gradually during the process of vacuum. The total surface settlement remains unchanged after vacuum preloading of the soft soil foundation for 2 months, which means that the consolidation of soft soil is approximately completed. The total settlement at the surface of the subsoil is approximately 440 mm. The cumulative settlement after construction is 4.2 mm in half a year and approximately 9.8 mm in 10 years by the predicted method, which satisfies the requirements of the settlement control. It is concluded that the method of vacuum preloading combining mixing pile can significantly improve the tram soft soil foundation.