Triaxial Test and DEM Analysis of Ballast Aggregate with Angularity Breakage

A series of triaxial monotonic compression tests were conducted to study the influence of angularity breakage on the deformation and mechanical properties of railway ballast. Different confining pressures were applied to ballast samples, including 10, 30 and 60 kPa to study the axial strain, volume strain, deviator stress and ballast particle size variation. In addition, breakable ballast model was built using discrete element method (DEM) to study the location and quantity of angularity breakage under different confining pressures. The comparison between test and stimulation results indicates that with increasing axial strain, the ultimate deviator stress increases and finally reaches a stable value; the ultimate deviator stress increases with the confining pressure, showing a linear relationship. When the confining pressure increases from 10 to 60 kPa, the ultimate deviator stress increases from 93 to 387 MPa. The dilation strain deformation also increases with the confining pressure. For example, when the confining pressure is 10 kPa, ballast sample hardly experience dilation strain deformation; when the confining pressure is 60 kPa, the dilation strain deformation is 0.21%.The amount of breakable angularity increases with the axial strain and angularity breakage mostly happens near the loading surface.