Study On Settlement Characteristics And Treatment Measures Of Loess High Filling Platforms On Existing Railway Passenger Dedicated Line

With the rapid development of high-speed railway in Northwest China,the settlement of loess high-filling platforms is becoming more and more prominent.Therefore,it is of great significance to reveal the settlement characteristics of loess high-filling platforms and put forward effective treatment measures.This thesis is based on the treatment project of a high-speed railway passenger station.According to the actual settlement data,this thesis analyzes the settlement characteristics of the platforms;on the limitations of the upper structure of the platforms and the particularity of the saturated filling soil in the platforms,two treatment measures are put forward in this thesis,such as the compacted lime cement soil piles and the dry-mixed cement sand piles;in addition,the method of model test and numerical simulation are used to study the treatment effect in this thesis.The main research contents and achievements are as follows:(1)The settlement observation data of the platforms are fitted to obtain the conclusion that the settlement-time curve of the platforms conforms to the hyperbolic model.(2)The influence of lime content on compactability and strength of cement soil is studied by compaction test and unconfined compressive strength test.(3)Based on the support project,the quality of piles in the saturated soils of the compacted lime cement soil piles and the dry-mixed cement sand piles is studied by the method of model test.The strength value of the piles and the decrease value of the soil moisture content around piles are obtained after 28 days.(4)Based on the results of model test,the design of the composite foundation is carried out by using the compacted lime cement soil piles with lime content of 3% and the dry-mixed cement sand piles with cement contend of 10% respectively.It is proved that the two treatment measures are feasible.(5)Based on the design scheme,the composite foundation is numerically calculated by using finite element software Midas-GTS,and the settlement characteristics of composite foundation are also analyzed.Based on the research results and suggestions,this thesis will accumulate experience and provide significant reference for the future design of similar projects.