Formation Mechanism and Stability Analysis Method for Wedge Loess Collapse

摘要

Wedge loess collapse is one of the important forms of loess collapses. Wedge collapse is mainly controlled by two structural planes whose tendencies are opposite. In the process of slope excavation, the unloading effect on the slope surface results in the compressive stress in the slope body to be readjusted, stress difference of slope body increases gradually from inside to outside, and the free surface in the slope body becomes slack and deformed. The original joint fissure of slope expands gradually. When the wedge is in a state of criticality, a sliding trend emerges on a sliding surface. If the shearing strength of the cement on this sliding surface could not resist the sliding force, the load gradually and rapidly moves to another slide surface, and a wedge collapse will arise. According to the destruction mechanism of wedge collapses, the model of geomechanics is proposed. Formulas are established to calculate the coefficient of stability of wedge and various structural planes by combining the limit equilibrium equation with Mohr-Coulomb strength criterion. The stability analysis method of wedge loess collapse is put forward. The research results provide the theoretical basis for the quantitative evaluation of the stability of loess collapse and they have important reference value for the design and construction of loess collapse control.