Three-stage collapsibility evolution of Malan loess in the Loess Plateau

•Three-stage collapsibility evolution of Malan loess in the Loess Plateau is investigated.•The weak connection mode and vertically distributed particles constitute the natural loess with metastable structure.•The decrease of medium and large pores in soil is related to pressure, while the increase of small pores is related to water.•The structural yield stress of soil determines the peak value of collapsibility pressure.