Experimental Research On Expansion Regularity Of Mineral Mudstone Based On High-speed Railway

Expansive soil is an important disease in engineering,with the rapid development of China's high-speed railway,new railways sometimes inevitably cross expansive soil areas and cause arch disease.Sampling of mudstone in the upper arch section of a high-speed railway is studied.The expansibility of expansive mudstone is determined according to the classification standard of rock and soil in railway engineering,it is found that the expansive mudstone in the foundation of the high-speed railway is "no" expansive mudstone or weak expansive mudstone,but there are many upper arch diseases in high-speed railway,it shows that mudstone with "no" expansibility and weak expansibility determined by current railway codes will still cause harm to high-speed railway,in order to grasp the expansion law of expansive mudstone foundation in high-speed railway.Therefore,it is necessary to study the low clay mineral mudstone with "no" expansibility or weak expansibility as determined by the current railway code.In this paper,the foundation mudstone in the upper arch section of a high-speed railway is taken as the research object,the method of combining indoor characteristic test,indoor expansion test and in-situ test is adopted,the micro-characteristics and expansion law of mudstone in high-speed railway foundation are systematically studied,in order to provide basic data and technical support for the design,construction and operation of expansive soil foundation of high-speed railway.The main research work is as follows:Taking the mudstone sampled from the upper arch section of high-speed railway as the research object,obtaining the physical properties of mudstone in the foundation of the railway line through laboratory tests,Analyzing the Basic Physical Characteristic Index of Mudstone by Mathematical Method,the comprehensive index of mudstone expansibility of high-speed railway foundation is obtained,in order to judge the expansibility of low clay mineral mudstone based on high-speed railway.Studying the micro-characteristics of remolded mudstone and original mudstone in the upper arch section of the high-speed railway,analyzing the relationship between dry density of remolded mudstone and micro-pore distribution,expansibility of original mudstone and micropore distribution,The relationship between micro-structure and macro-physical index is established.Expansion test of small size mudstone in laboratory was carried out,obtaining the law of humidification and expansion of small size mudstone,The parameters of swelling process of small-sized mudstone,water content of joints,are obtained.and analyzing the relationship between parameters of swelling process and indexes of mudstone swelling characteristics.Expansion deformation test of large-scale mudstone is carried out,the law of influence of largescale mudstone pore loss soil on expansion,the law of growth of large-scale mudstone expansion deformation,the relationship between overburden load and expansion deformation are obtained.In situ expansion test was carried out,the growth law of swelling deformation of in-situ mudstone and the relationship between overburden load and swelling deformation of in-situ mudstone are obtained,the law of mudstone water content growth at different horizontal and vertical distances,the law of mudstone horizontal seepage velocity change under different overlying loads and different horizontal distances,and the law of mudstone vertical seepage velocity change under different overlying loads and different vertical distances are obtained.