Study On Subgrade Replacement Application In Settlement Treatment Of Lanzhou-Xinjiang Line

The roadbed frost heaving and thaw settlement,mud pumping,cement hardening,and ballast pouches have long been common in the Wuxi-Shawan section of the Lanzhou-Xinjiang railway line,since the speed increase of the train to 160km/h in May 2016,a relatively large settlement deformation occurred on the K2164+750-K2168+900 section.These major deformation settlements are mainly distributed in the sections of embankments,culverts,and the transitional sections at both ends of the bridge.The occurrence of such conditions has a great influence on the effect of the speed increase of the trains,and poses a great safety risk to trains.The Lanzhou-Xinjiang line is carrying a heavy transportation task every day,it is not feasible to treat the subgrade settlement for long periods of interruption of the train operation.Therefore,it is necessary to carry out settlement improvement without affecting the normal operation.The main research completed in this article is as follows:1.In accordance with the settlement of the typical section of the Lanzhou-Xinjiang line,in-situ test analysis,moisture content test analysis,indoor test analysis,and frost heave analysis are carried out,the causes of typical segment settlement is found out,and parameters for the numerical simulation calculation and analysis are prepared;2.By collecting data on typical sections of the Lanzhou-Xinjiang line and on-site investigations,the analysis shows that the settlement of the typical section is mainly composed of three parts: the settlement caused by the self-weight of the track system,the settlement caused by frost heave thawing,and the settlement caused by the dynamic load of the additional train;3.By checking the related literature to study the common subgrade settlement control measures for existing lines,in combination with the actual conditions of the Lanzhou-Xinjiang line project,a subgrade replacement treatment scheme is selected for the settlement of the typical section,and the fluid-solid coupling analysis under vibration loads is performed using numerical simulation software FLAC3 D.4.Various calculation conditions are designed for factors such as replacement rate,replacement slope,train speed,and replacement depth,and the effects of multiple replacement plans from the aspects of drainage and settlement by qualitative and quantitative comparison analysis are determined to give the method for selecting subgrade replacement schemes in similar projects.