哈佳铁路中等压缩性粉质黏土地基沉降特性研究

Study on the Settlement Properties of Medium Compression Silty Clay Foundation in Ha Jia Railway

中等压缩性粉质黏土地基在铁路工程建设中十分普遍,研究其地基沉降发展规律,合理确定地基处理方案,可提高铁路工程建设的经济性和安全性。文章对哈佳铁路典型中等压缩性粉质黏土地基设置沉降观测试验段,分析其在路堤荷载作用下的总沉降、工后沉降变化情况,研究此类地基土的沉降特性。结果表明:(1)在路堤平均填高7.05 m时,试验段地基沉降主要发生在浅层0~8 m以内,约占总沉降的75%;(2)地基经过6个月静置期,工后沉降在70 mm以内,地表沉降的收敛迹象尚不十分明显,剩余沉降量占总沉降量的15%~25%;(3)工后沉降理论上满足设计速度200 km/h的客货共线铁路和200 km/h及以下级别城际铁路的设计要求,但分析此类地基的工程适用性时,尚应考虑现场沉降测试的不确定性以及工程设计所需具有的安全余量。

Medium compression silty clay foundation is widespread in the railway engineering construction, study of the development law of foundation settlement and reasonable determination of the foundation treatment scheme can improve the economy and safety of the railway engineering construction. The settlement observation test section is set for typical compression silty clay foundation of Hajia railway,the total settlement under embankment load and the post-construction settlement are analyzed to study the foundation settlement properties. The results show that： when the height of embankment is 7. 05 m, the foundation settlement in test section occurs mainly in the osuperficial layer from 0 to 8 m, accounting for about 75% of the total settlement; after six months, the post-construction settlement is within 70 mm and convergence of the ground surface subsidence is not very clear,the residual settlement accounts for 15% ？ 15% of total settlement; Post - construction settlement theoretically meets the design requirements for 200 km/h mixed passenger and freight railway, 200 km/h and below level of intercity railways. But when analyzing the engineering applicability of this kind of foundation, consideration should be given to the uncertainty of site settlement test and a certain safety margin required by engineering design.