Dynamic Response And Cumulative Plastic Deformation Of Coarse Particle Filler In Subgrade Under Cyclic Loading

In recent years,China’s high-speed railway has been developing rapidly.As a business card of our country,the high-speed railway is already famous all over the world.At the same time,with the increase of the running speed of the train and the increase of the axle load,the accumulated deformation and fatigue damage of the subgrade are accelerated.In order to ensure the safety and stability of the high-speed railway,the high-speed railway has imposed strict requirements on the subgrade.This paper has carried out a series of studies on the dynamic characteristics and cumulative deformation development of coarse-grained fillers under cyclic loading.A series of static and dynamic triaxial tests of coarse particle fillers with different fine particle content,different water content,different confining pressure and different dynamic stress were carried out by the dynamic and static triaxial apparatus.The influence of factors such as physical state of the coarse particle filler,dynamic stress magnitude and cyclic loading times on the rebound characteristics and cumulative deformation of railway subgrades,the main conclusions are as follows:(1)The effect of water content and confining pressure on the principal stress difference is significant.When the water content is low,the stress-strain curve presents a strain-softening model.As the water content increases,the stress-strain curve gradually transitions from strain-softening to strain-hardening.In terms of particle content,the strength of the sample with 10% fines content is better than the samples with 5% and 15% fines content.(2)As the content of fine particles increases,the cohesive force tends to increase first and then decrease,and the internal friction angle decreases first and then increases;as the water content increases,the shear strength of the sample was obviously weakened,the cohesive force showed an increasing trend,and the internal friction angle showed a decreasing trend.(3)The dynamic elastic modulus first increases and then stabilizes with the increase in the number of vibrations.The increase stage is mainly concentrated in the first 10 cycles.The difference from low water content is the elastic modulus of the high water content(w = 8%)sample decreases again after about 1000 cycles of loading.The decrease of the water content,the increase of the confining pressure,and the increase of the dynamic stress will cause an increase of the elastic modulus.The effect of water content is the most significant.(4)The elastic strain increases with the increase of the water content.With the increase of the water content,the increase of the elastic strain slows down.The decrease of confining pressure and the increase of the dynamic stress will cause an increase of the elastic strain,they are approximately linearly related.(5)The deformation characteristics of the sample are closely related to the water content,confining pressure,and dynamic stress amplitude.The cumulative plastic strain was predicted and analyzed for sample deformation tends to stabilize and tends to damage the two different soil types.