Abstract: Loess collapse with toppling style is one of the common disasters in loess area. Based on its forming feature, the solutions of upper and lower bound for vertical fracture of the loess collapse are derived in light of the critical state of both static equilibrium and plastic flow. The underside attitude of the collapse is calculated by the Mohr-Coulomb criterion. Thereby the geometric characteristics of the collapse can be determined; then the stability criterion is established based on the balance of force and torque; and the stability evaluation of loess collapse with toppling style is realized. The kinematics equation for loess collapse with topping is built by its toppling deformation conditions. By solving the equation, the trajectory of the loess collapse with toppling style is reconstructed; and the range of the disaster can be detected. The research results reveal the forming mechanism of loess collapse with toppling style, so as to provide a theoretical basis for its governance approaches and its identification with the safe zone of construction project.

Key words: loess collapse, toppling style, stability criterion, influencing zone