A model for earthquake driven slope instabilities and morphologic landscape evolution

• Published in: Landslides and Engineered Slopes. Experience, Theory and Practice Vol. 1; pp. 2013 - 2021
• Main Authors: Voulgari, C., Utili, S., Crosta, G.B., Dattola, G., Hermann, R.L.
• Format: Book Chapter
• Language: English
• Published: CRC Press 2016
• Edition: 1
• Subjects: Upper Bound Theorem; Main Scarp; Slope Material; Limit Analysis Methods; Seismic Acceleration; External Work Rate; Logarithmic Spiral; Overburden; Failure Mechanisms; Yield Acceleration; Slope Toe; Cataclinal; Nazca Plate; Tension Cracks; Failure Line; Slope Stability Problems; Vertical Seismic Acceleration; Seismic Scenarios; Successive Failures; Landslide Event; Rock Avalanche; Critical Failure Mechanism; Atacama Desert; Friction Angle; Pseudo-static Approach
• ISBN: 1138029882; 9781138029880
• DOI: 10.1201/9781315375007-242

In seismic regions the evolution of landscape is often dictated by the occurrence of earthquakes with each seismic event being responsible for the triggering of one or more landslides. In this paper, an analytical model to investigate the morphologic evolution of slopes subject to earthquake excitation is presented. The use of the model is twofold: on one hand to identify the magnitude of past earthquake events by back analysis of the shape and the extent of the landslide, and on the other to predict possible future failures. The well-known pseudo-static approach is employed in this study to account for the seismic excitation, the successive events and the cumulative damage through long time periods and by successive earthquakes. An example case is also provided for one of the most seismically active areas in the world (located south of Iquique in northern Chile), where the presence of large rockslide and avalanches occurred at different times is well documented. This chapter presents an analytical model to investigate the morphologic landscape evolution of slopes subject to earthquake excitation. Seismic acceleration can directly trigger slope failures and at the same time cause damage within the slope material, predisposing it to successive failures under different triggering factors or earthquakes of smaller magnitude. Instabilities along slopes affected by strong and repeated triggering events can develop multiple failures with progressive retrogression of the main scarp up to a stable condition. Limit analysis methods allow obtaining rapid solutions for the examination of slope stability problems under different constraints, for example water table, seismic action, tension cracks, reinforced soils. The upper bound theorem of limit analysis associated with pseudo-static approach was employed to evaluate the slope yield acceleration that could have caused failures of known geometry and soil characteristics in the past and also to predict future failure mechanisms of slopes under seismic effect.