Experimental investigation of particle abrasion and breakage characteristics and mechanical behavior of heavy-haul railway ballasts subjected to repeated loading
Experimental investigation of particle abrasion and breakage characteristics and mechanical behavior of heavy-haul railway ballasts subjected to repeated loading
In order to study the characteristics of granular wear and breakage and mechanical behavior deterioration of granular ballast under cyclic dynamic load of heavy-load trains,three large-scale dynamic triaxial tests under three different dynamic stress amplitudes were carried out.Through laser scanning and three-dimensional reconstruction of dyed ballast particles,the wear and fracture characteristics of ballast particles with different diameters under different cyclic loading stress states ere quantitatively analyzed.The macroscopic mechanical properties and mechanical behavior deterioration of samples under cyclic loading were analyzed in depth.The research results are shown.After cyclic loading,the ballast particles are generally broken from the original particle size to the adjacent particle size,and occasionally broken to the separated particle size.In addition,a small amount of ballast particles accounting for about 1%of the mass are broken to the minimum particle size of 4.75～22.4 mm.Under the same cyclic loading dynamic stress amplitude,with the increase of particle size,the mass proportion of ballast particles broken to the adjacent particle size generally increases.During cyclic loading,there are three typical types of particle wear:sharp angle wear,edge wear and surface texture change.The maximum wear depth of particles under dynamic stress amplitude of 230 kPa(corresponding to 25 t axle load)is 0.36～5.2 mm,and the average wear depth is 0.03～0.62 mm,the degree of particle wear increases with the increase of particle size,and the number and probability of sharp corner wear are more,followed by edge wear.Before and after cyclic loading triaxial test,the variation amplitude of particle content of each particle group and the deviation distance of grading curve increase with the increase of dynamic stress amplitude,and the three particle breakage indexes of Bg,Br and BBI increase with the increase of dynamic stress amplitude,both Br and BBI have the same degree of response to changes in dynamic stress amplitude and are more sensitive.The axial cumulative plastic strain,damping ratio and rebound modulus of the specimen increase with the increase of dynamic stress amplitude.The research results can provide theoretical basis and technical reference for the long-term service performance deterioration assessment and maintenance of heavy haul railway granular ballast bed.
维普
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