| With the rapid development of economy,the requirement of heavy load railway transportation capacity is also increasing,so the implementation of heavy load railway capacity expansion and transformation plan is extremely urgent.For existing lines in revamping/expansion of overloaded railway will make train axle load increases,the railway bed under more dynamic loading,and under the action of groundwater in rain and snow weather,railway subgrade mud pumping prone to uneven settlement,embankment collapse,and many other diseases,it seriously affected the overloading of railway transport safety and economic benefits,hindered the implementation of railway overloading capacity improvement plan.Therefore,it is of great significance to study the wetting deformation characteristics of subgrade soil under the coupled action of cyclic load and immersion and the variation law of subgrade strength for the smooth progress of energy expansion and transformation plan.In order to simulate the actual water inflow process of roadbed and analyze the mechanism of disease,GDS dynamic triaxial apparatus and constant water head markov bottle are used to carry out indoor cyclic load immersion test.Considering that the subgrade of energy expansion and reconstruction will bear more dynamic load,the indoor triaxial repeated loading sequence of dynamic resilience modulus of subgrade soil of heavy-haul railway is studied,and the changing rule of dynamic resilience modulus is analyzed,so as to provide help for the smooth implementation of energy expansion and reconstruction plan.The main work and research are as follows:(1)The field investigation of typical disease lines was carried out,and the basic situation of the disease roadbed soil was analyzed based on relevant field data.The influence of water on the roadbed soil was revealed,and the indoor basic property test was carried out on the samples of the disease roadbed soil,and the main causes of the disease were analyzed.(2)The dynamic humidification test was carried out on the samples under indoor cyclic load,and the variation rules of strain,hysteretic curve,dynamic elastic modulus,immersion rate and sample moisture content distribution under different dynamic stress amplitude,compaction degree,initial moisture content and other factors were analyzed.It is found that the strain increases with the increase of dynamic stress amplitude and initial moisture content,and decreases with the increase of compaction coefficient.The deviation slope of the hysteretic loop to the right decreases gradually due to strain softening.The water infiltration rate increases rapidly with the increase of time and then gradually slows down.It decreases with the increase of compaction coefficient,dynamic stress amplitude and initial water content.The influence of water infiltration rate on the first 100 min of different initial water content is not obvious.The dynamic elastic modulus increases with the increase of the vibration number before immersion,decreases with the increase of the vibration number after immersion,increases with the increase of the compaction coefficient,and decreases with the increase of the initial moisture content and dynamic stress amplitude.The water content of the sample was mainly distributed at the bottom of the sample,and the cyst drum phenomenon occurred at about 40 mm.(3)To study the dynamic modulus of resilience of overloaded railway subgrade soil,scholars at home and abroad for reference,study and combined with the actual working condition of the information obtained is applicable to the overloaded railway subgrade soil dynamic modulus of resilience of indoor triaxial repeated load sequence,and different influence factors are analyzed through indoor load sequence test under dynamic modulus of resilience. |
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