Experimental and numerical study on collapse of quasi-two-dimensional bilayer granular column

•Impact of particle sequence on granular column collapse is investigated extensively.•Small particles moves slower than large particles, for columns with mixed size of particles, the basal particles dominate the column collapse.•The final run-out distance (Lf/L0) and peak kinetic energy (EK,peak/E0) of the four types of column increases with the increase of AR.•Both Lf/L0 and EK,peak/E0 are mainly affected by the properties of upper particles.