Study On Test And Calculation Model Of Arch Deformation On Mudstone Foundation Of High-speed Railway

There have been a large number of new and unforeseen problems with the increasing proportion of high-speed railway and passenger special line in China.The upper arch of high speed railway subgrade on the basis of no or weak expansive mudstone judging by the?Code for rock and soil classification railway engineering?(TB10077-2001)has brought great harm to the safety of driving.The research on the problem of high speed railway subgrade upper arch is rarely reported at home and abroad at present.This paper systematically studies the deformation law of the upper arch on the mudstone foundation and the calculation model of the upper arch amount on the subgrade.The method of combining field survey,indoor test,theoretical calculation analysis and numerical simulation is used based on the high-speed of Lanzhou to Xinjiang.The main research work is as follows:(1)The terrain,geomorphology,geological stratification and geological structure of the upper arch are analyzed according to the field survey,geological radar detection and sampling on the high-speed of Lanzhou to Xinjiang.It is concluded that the upper arch on the subgrade is caused by the foundation soil.(2)A small amount of montmorillonite was found in the soil by X ray scanning and the free expansion rate was higher in the laboratory.Then the dilatancy experiment of foundation soil under different thickness,different water content and different overloading is carried out by self-made test device.The development process and development stage of swelling deformation after foundation water soaking are analyzed.The influence rule of different thickness,water content and overburden load on the expansive deformation value of foundation soil is analyzed.(3)The formula of swelling force is derived from the microstructural montmorillonite in mudstone expansion using the meso mechanics theory of composite material.The calculation formula of expansion force in unit volume is simplified with the help of the existing research conclusions.The calculation model of upper arch with the swelling state of mudstone-overlying load-water content-thickness is constructed by means of superposition method and Sc,the principle of elastic mechanics and the basic principle of rock and soil mechanics.(4)The calculation results and the experimental results are compared and analyzed and the correctness of the calculation method is verified.An indoor test numerical model is established to consider the expansion force.The feasibility of the numerical simulation method is verified by comparing the experimental results,the theoretical calculation results and the numerical model results.The field test results,numerical simulation results and theoretical calculation results of mudstone are compared and analyzed.The generalization of the numerical simulation method and the applicability of the calculation model for the upper arch deformation of high-speed railway mudstones are demonstrated.(5)The maximum upper arch value with high-speed railway of Lanzhou to Xinjiang based on the arch calculation model is predicted,and the stability of roadbed is determined.The main reason of the subgrade upper arch is expansive mudstone and water.It is found that the subgrade upper arch is changing slowly,and some subgrade upper arch has stabilized by taking an open cut ditch.The measures are of great significance to solve the subgrade upper arch with with high-speed railway of Lanzhou to Xinjiang.