Evaluating the Behavior of Geogrid-Reinforced Earth Dams under Static and Dynamic Loads

Abstract

Since many earth dams are constructed already or are under construction in the earthquake prone areas, their safe design against earthquake is very important. The precise investigation of seismic stability of the earth dams is among the complex issues in the dam construction area. Besides, diversity of the dam body dynamic properties as well as diversity of the components and thickness of the foundation is among the factors that play a significant role in the dam dynamic response. Today, thanks to the science and technology progresses, it is possible to develop and construct the earth dam with considerable heights. The most common type of the dams is the earth dam with clay core. The function of the clay core is to seal the dam and to reserve the water. The more important issues in dam designing are analysis of their slope dynamic stability against the seismic loads. Therefore, in this study the seismic dynamic analysis of an earth dam is investigated by the finite element method and the GeoStudio software. The aim of these analyses is to investigate the dynamic response of the earth dams in different heights of the dam core and crest as well as to obtain the optimal position of the clay core slope in designing these dams. Studies in this field can be investigated under different conditions for unreinforced slope sand for those slopes reinforced with geogrid materials. This article is composed of two main parts. The first part, using the GeoOffice software and based on the limit equilibrium method is addressed to analysis the earth dam slope stabilities under the steady state and rapid draw down conditions, with and without the seismic loading. Then, based on the finite element method in the PLAXIS software, the analysis of the slops reinforced with geogrid is addressed. Besides, the effects of the static and dynamic loadings on analyses are considered and the safety factor values in each status are compared with the unreinforced slopes. The obtained results showed that by using the geogrid in the slopes under these conditions, the safety factor is enhanced. Likewise, by comparing these results, it can be concluded that the slope angles of the earth dam are increased and the dam embankment volume is decreased. Besides, through comparing the results, the optimal values to recognize the various geogrids, number of the geogrid layers, vertical distances and length of the geogrids are obtained.