The Vibration Subsidence Study On The Cement Loess Of Heavy Haul Railways Subgrade, South Central Jin

Jin South central heavy haul railway passage constructed in the Loess Area is not only an important railway but also the first axle load of30tons of heavy haul railway in China. Its line is long, geological condition is complex, so it is very stringent requirements on subgrade settlement and deformation. Especially it along after high intensity thick loess area, which has a subgrade treatment engineering quantity and lack quality packing.Therefore, modification on the loess to meet the requirements of heavy haul railway roadbed is of importance to engineering value and economic benefit.In this paper, it analyse the lines of the regional engineering geological environment, summary the results of previous studies, carry out a variety of cement improved loess for static and dynamic test, study the cement improved loess by various mechanical properties and engineering properties with the combination of MIDAS/GTS numerical simulation analysis. It focus on the railway subgrade in heavy haul train time, small amplitude vibration loads subsidence problems. The study obtaine some valuable achievements by combining field exploration and indoor test with calculation and simulation.(1) Having a field investigation, collecting the Jin South heavy haul railway passage along the related geological data, mastering what the heavy haul railway is, especially the study of engineering geological conditions on site; and analysing the loess material composition and conventional physical and mechanical index test.(2) Selecting the typical subgrade soil. The optimal cement ratio between concrete and loess can be obtained through the analysis of static characteristic of loess improved with different contents of cement and diverse methods of soil testing experiments.(3) Analysing design parameters of Jin South heavy haul railway to make sure roadbed, static, dynamic load; The mathematical model is establised through simulating different content of cement improved loess used as roadbed vibration settlement characteristics and dynamic constitutive relationship under all kinds of loads with GDS three triaxial.(4) Using the finite element numerical simulation to establish the three-dimensional heavy haul roadbed model which based on the the MIDAS/GTS related to static and dynamic model. Then calculate the change of stress and settlement deformation of the cement improved loess as the bedding bottom layer packed in the self-weight stress, heavy haul train static load and heavy load trains long duration, small amplitude vibration load.