A new method (Permanent Displacement Ratio Theory: PDRT) is proposed for analyzing dynamic stability of rock slope under seismic loading. The PDRT takes permanent displacement of rock slope as failure criterion, and provides an index which has a clear physical meaning to evaluate the dynamic stability of rock slope based on dynamic strength reduction theory. Hence, the PDRT fully combined the advantages of seismic permanent displacement method and dynamic stability factor method. An example given by E. Hoek and J. W. Bray is presented to demonstrate the computational process of PDRT, and then the dynamic stability law of the example under different scales of seismic intensity is analyzed. Finally, the PDRT is applied to study a rock slope case in Wenchuan earthquake regions of China, and a dynamic stability factor of 0.95 is obtained, the result matched the actual situation well, which testified the practicability of the PDRT.
The dynamic stability issue of rock slope under seismic loading is a common focus of geotechnical engineering and earthquake engineering. At present, the evaluation methods of rock slope's dynamic stability mainly include two categories: Seismic Permanent Displacement Method (SPDM) and Dynamic Stability Factor Method (DSFM). The SPDM is well studied by plenty of scholars (Cai & Bathurst 1996, Wang & Lin 2010, Baziar et al. 2012), but this method has not been widely accepted in practical engineering application, because it cannot give a unified criterion of failure. Simultaneously, the DSFM mainly include: pseudo-static method (Yang et al. 2014), dynamic time history method (Liu et al. 2003) and dynamic strength reduction method (Li et al. 2007), etc. The DSFM can give a unified factor to evaluate the dynamic stability of rock slope, however it still has many defects, such as: the pseudo-static method cannot take dynamic features of slope material and fluctuation characteristics of seismic loading into account; the dynamic time history method can provide a change process of slope's dynamic stability during earthquake, but without the capability to give a synthetic index for evaluating slope's entire dynamic stability.