Near-field ground shock features are analyzed according to the seismological record of the May 12 Wenchuan earthquake made at the Wolong observation station. A numerical analysis model is established by taking the record as the input seismic load and a real high and steep rock slope on the bank of the Zipingpu Reservoir. The acceleration response and shear strain increment distribution features at different locations of the slope under horizontal seismic force are analyzed using Plaxis software. The moment when the widest plastic zone occurs for the slope is obtained by time history analysis. The corresponding stability factor of the slope at that moment is calculated using the strength reduction method (including shear strength and tensile strength). The above is the Time History Analysis–Strength Reduction Method presented in this article. In addition, the stability factor of the slope can be calculated using the pseudostatic method by taking the seismic force as the external load. This is the Time History Analysis–Pseudostatic method put forward in this paper. Analysis results demonstrate that, as far as the studied high and steep slope is concerned, at 31.89 s, the stability factor calculated with the Time History Analysis–Strength Reduction Method is 1.004, which is slightly larger than the 0.833 obtained using the Time History Analysis–Pseudostatic Method (Spencer method). Both results demonstrate that there is collapse and sliding failure of the localized rock mass at the top of the slope at that moment because of joint fracture. Field investigation after the earthquake further verified the calculation result, proving to a certain degree the rationality of the analysis method presented.

Near-field seismic motion characteristics are analyzed in accordance with records of the 2008 Ms8.0 Wenchuan Earthquake measured at Wolong Station, upon which the determination of seismic load is introduced. Dynamic response features, such as acceleration, displacement and stress, of high steep rock slopes on the banks of Zipingpu Reservoir at a variety of locations resulting from horizontal seismic force are analyzed with a numerical analysis routine. The dynamic amplification factor on the slope top is determined, leading to a characterization of the mode of failure of the high steep slope. Analyses show that the dynamic amplification factor at the top of the slopes is about 1.34; however, dynamic response deformation features and stress state at different positions on the slope vary. Earthquake damage of the high steep rock slopes consists mainly of partial avalanche of the rock mass at the top of the slopes by joint cutting. Field investigations after the earthquake have partially confirmed the numerical analysis results presented in this paper.

Slope of subhorizontal layer structure is among typical natural structures and the different soft and hard rock combinations in upper and lower slope parts differ in seismic response. Taking into consideration some slope failure phenomena of two-sided slopes with banded structure ridges in “5.12” Wenchuan Earthquake, simulation experiment are made to research two types of horizontal structure slopes with hard-upper and soft-lower and soft-upper and hard-lower parts, by means of numerical simulation analysis and simulating experiment on vibration table. Research results show that for slope with hard-upper and soft-lower parts, its upper hard rock body is inclined to undergo global shearing deformation, along contact layer with underlying soft rock body, and the upper slope body is apt to go through collapse and pull-crack. For slope with soft -upper and hard -lower parts, influenced relatively more strongly by its lower hard rock part, rock body possibly shows cracking deformation similar to sliding and compression cracking, which may extend upward or downward along the contact layer. Moreover, the shoulder of two-sided slope is apt to undergo pull-crack and that, to some degree, relieves integral stress and sliding deformation of the upper soft rocky body. Therefore the whole rock body goes through little sliding deformation. Research result confirms the actual shatter slope failure, which further verifies the view that horizontal seismic action force plays main role in slope failure.