Study On Dynamic Characteristics Of Aeolian Sand Filler And Dynamic Stability Evaluation Of Railway Subgrade Bed Bottom Layer

Aeolian sand has been used as a bottom filler for railway subgrade bed in engineering practice,but there are few studies on the dynamic characteristics of aeolian sand filler and the dynamic stability evaluation for railway subgrade bed bottom layer.Accordingly,taking the aeolian sand filler under a typical section of Heruo Railway line as the research object,a series of static and dynamic triaxial tests were conducted to systematically study the dynamic characteristics of aeolian sand filler under train load,which provides experimental basis for the dynamic stability evaluation of the railway subgrade bed bottom layer.The main research work and conclusions are as follows:(1)The stress-strain relationship curve and the shear strength index of aeolian sand filler by static triaxial tests.The variation of stress-strain relationship with different moisture content,compaction degree and confining pressure was studied systematically.It is found that the hyperbolic model of Shen Zhujiang can simulate the stress-strain relationship of aeolian sand fillers well.(2)The dynamic triaxial test of aeolian sand fillers was carried out to systematically investigate the dynamic properties of aeolian sand fillers under different dynamic stress amplitudes,moisture content,confining pressure,compaction degree and frequency.The resilience modulus and dynamic strength and critical dynamic stresst estimation formulas are obtained by constructing the cumulative plastic strain and elastic strain prediction models,and a backbone curve model considering the stiffness hardening characteristics of aeolian sand is established.(3)The critical dynamic stress and accumulated plastic deformation are taken as the control indexes of the railway subgrade bed bottom layer,and the dynamic stability of the aeolian sand filling subgrade is evaluated from the two aspects of strength and deformation.The results show that the strength and deformation of aeolian sand fille with "core-spun" subgrade structure can meet the requirements.