Numerical Simulation Of Soft Soil Roadbed And Settlement Prediction Of New Fast-speed Railway

In order to promote the development of Poyang Lake regional economy,JiuJiang-JingdeTown-QuZhou fast-speed railway was planned with the development of urban cluster.To satisfy the operating conditions of EMUs,fast-speed railway has put forward higher requirement on the railway comfort and stability.fast-speed railways' settlement deformation observation and assessment is the key to ensure the quality of the laying of track structure during the time of fast-speed railways' construction,the work is also the premise to ensure fast-speed railway operation comfort,stability,operation safely.In the design and construction process of JiuJiang-JingdeTown-QuZhou fast-speed railway,the line will inevitably pass through Poyang Lake basin lacustrine soft soil area,the settlement of roadbed directly affect traffic safety after the completion of the train,so some measures should be taken to reduce the settlement on soft soil foundation.This paper is aim at the reinforcement effects of composite foundation of mixing pile and CFG pile,research from two aspects: calculation and prediction of surface subsidence.It provides the technical support for the fast-speed railway subgrade construction control and has a wide range of engineering application value.Based on the observation and assessment work settlement of JiuJiang-JingdeTown-QuZhou fast-speed railway line project,this paper select the JiuJiang-JingdeTown-QuZhou fast-speed railway's second section's third work area of first branch's composite foundation engineering as the research object.According to the test parameters,the paper use MIDAS/GTS simulation of the project at the typical section;and according to the settlement data of the segment,the paper use two curve fitting method applied in prediction of subgrade settlement,and on this basis,analysis the applicability of two settlement prediction methods,obtain a reasonable result,and it has certain reference and guiding significance for the evaluation of the settlement deformation of the fast-speed railway in the future.the main work of this paper includes the following aspects:(1)Based on the existing research results,the paper introduces the cause,distribution and characteristics of soft soil in detail,discusses the harm and treatment of instability of soft soil foundation and the settlement characteristics of soft soil roadbed.Besides,the calculation method of the composite roadbed settlement is also summarized.(2)The principle of strengthening foundation of the mixing pile and CFG pile and the construction operation points are discussed briefly.The finite element analysis software MIDAS / GTS of geotechnical engineering is used to simulate the settlement deformation of railway roadbed placed in layers under the composite foundation of CFRP pile and CFG pile.The feasibility of the foundation reinforcement method is verified by comparing the model calculation result with the standardized requirements.(3)Additionally,the observation method of roadbed settlement of express railway,the principle of layout of observation section and observation point,the principle of component embedding,the measurement accuracy and frequency requirement are also investigated.(4)Based on the measured data,the applicability of the hyperbolic method and the gray prediction method in the prediction of roadbed settlement of Jiujiang-Jingde Town-Quzhou Railway is discussed respectively.The paper emphatically researches the influence of time interval and data on prediction accuracy.The results indicate that the shorter time interval leads to more data.And result obtained by hyperbolic method has higher accuracy.This also determines the conditions for the assessment of the roadbed.Large observation data is required as a prerequisite.