MECHANISM AND PHYSICAL PREDICTION MODEL OF INSTABILITY OF THE LOCKED-SEGMENT TYPE SLOPES

The slope, whose stability is controlled by the locked segments within a potential slip surface, is referred to as the locked-segment type slope. It is well known that the instability prediction of slopes is a worldwide scientific problem. We suggest here that solving the instability prediction of the locked-segment type slope can be taken as a breakthrough because it has the explicit instability mechanism. In the present study, the classification method of locked-segment type slopes is discussed. It is pointed out that there exists an essential connection between three-phase creep development of the locked-segment type slope and the damage process of the locked segment, and that a locked-segment type slope will evolve into the tertiary creep stage when the cumulative damage of the locked segment reaches its volume dilation point. It is found that the peak strength point and the residual strength point of the locked segment can be regarded as two characteristic catastrophe points, respectively corresponding to the occurrence of the abrupt landslide and progressive one. Combining a one-dimensional renormalization group model with the strain-softening constitutive model of the locked segment, we establish the mechanical expressions among the volume dilation point, the peak strength point and the residual strength point and hence present a physical instability prediction model of locked-segment type slopes. The evolutionary mechanisms of three typical cases, the Yanchihe avalanche, the Xintan landslide and the wedge rockslide on the left abutment of Libby Dam, are reasonably explained and satisfied retrospective analysis results are obtained by the model. Finally, some related supporting techniques and applying principles about the model are introduced for actual applications.