Study On The Treatment Method And Technology Of Mud Pumping Disease Of He-Yan-Ri Railway Expansive Soil Subgrade

The He-Yan-Ri Railway is an important line in China’s railway network.However,due to the early construction period and the lack of adequate understanding of the engineering characteristics of the expansive soil,the expansive soil was largely used as the filler of the railway subgrade foundation bed without any effective treatment.With the increase of speed,operation speed and traffic volume,and the double-track construction makes the subgrade foundation more difficult to drain.Expansive soil road gene is an engineering characteristic of expansive soil.Under the combined action of train dynamic load and meteoric precipitation,it leads to the repeated occurrence of slurry and mud-pouring disease in the subgrade bed of He-Yan-Ri Railway.Although the public works maintenance and maintenance units along the line have taken a variety of measures to improve the disease,the effect is often poor,repeated rectification and repeated failure,the cost of a lot of financial and material resources can not be the root cure of the mud-turning disease,making the disease seriously harm the safety of the line.Based on this background,this paper qualitatively analyzes the occurrence mechanism of the mud pumping disease of He-Yan-Ri railway,and takes the characteristics of expansive soil and water as the main causes of the disease,so as to put forward a comprehensive treatment scheme of chemical improvement of subgrade soil and setting up a confining bed to block surface water.This paper selected He-Yan-Ri railway roadbed expansive soil as the research object,through adding different content in the soil(3%,5%,7%,9%)of TGRM special cementitious grout,use a series of soil test to study the expansion of the expansive soil characteristics and strength characteristics before and after improve,finally it is concluded that the optimum addition amount of improved expansive soil is 7%.At the same time,this paper uses a new type of cementitious material developed by our research group are studied in laboratory,namely MBC cementitious material,to form a new polymer by mixing MBC cementitious material of different dosages(8%,8.5%,9%,9.5%,10%)with graded gravel of different gradation types(close to the upper,median,and lower limit of AC-10 gradation range).According to the Marshall design method,the optimal mix ratio of MBC polymer was obtained,that is,the grade is close to the upper limit of AC-10 grade range,and the dosage of MBC cementifying material is 9.5%.The water resistance,water stability,low temperature crack resistance and aging resistance of MBC polymer with optimal mix ratio were tested.Then,the numerical simulation of the railway subgrade before and after the renovation was carried out.Through the simulation results,the overall strength of the subgrade was effectively improved and the deformation of the subgrade was reduced after the renovation.Finally,according to the treatment scheme,the soil was improved by grouting method,and a complete set of construction technology of " pulling out four sleepers and backward sleeper " to spray MBC polymer at high pressure on the foundation bed of expansive soil subgrade is studied to form an integral sealing layer to isolate the infiltration of atmospheric precipitation,so as to control the mud-pouring of railway subgrade foundation bed.