PERFORMANCE OF SLOPE UNDER SEISMIC CONDITIONS

Abstract

The seismic stability of earth slopes has been a topic of considerable interest in geotechnical engineering practice for the past few decades. The failure of slopes during earthquakes can lead to the significant losses. The seismic stability of slopes is influenced by many factors and complete slope stability evaluation must consider the effects of each like geological, hydrological, topographical, geometrical, strong ground motion parameters during an earthquake and soil characteristics all influence the stability of a slope. Hence, the seismic performance of these structures requires appropriate evaluation during their design. Such performance is best evaluated through an assessment of the potential for seismically induce permanent displacements. This paper presents numerical studies on response of unreinforced slopes due to dynamic loading based on finite element analysis. Model embankments of silty sand and clayey sand have been considered. The parameters selected for the dynamic analysis includes embankment of height 5m and 12m with gentle slope 300 and steep slope 500. The sub base depth (D) is varied with height of the slope (H) with D/H ratio from 0.5 to 2.0.The various past earthquake records are considered with different amplitudes ranging from 0.1g to 0.4g.The results are presented in the form of factor of safety against slope failure under static and seismic conditions and settlement of crest of slopes. It is observed that as the height of the slope increases the maximum crest displacement increases for both type of soil and sub soil conditions.