Numerical Analysis of Passive Earth Pressure under Static & Cyclic Surcharges

Learning about earth pressure is an important factor in problems concerning geotechnical engineering. Earth pressure depends on many factors such as the nature of surcharge, soil properties and soil-wall Interaction. It is also a function of amount and type of wall deformations. Cyclic surcharges such as traffic loads, explosions and the impact of passing heavy trucks and vehicles on the backfill soils will Increase the normal stresses and lead to considerable changes of earth pressures. They also cause Strains which results in instability of retaining structures. The variety of factors influencing the soil-wall interaction may cause the dynamic earth pressure to become very complicated and hence difficult to be predicted. In addition, the distribution of dynamic earth pressure and its point of application along the wall are still unclear. In order to clearly explain the earth pressure under cyclic surcharges, both Numerical and experimental models need to be considered. Therefore, passive earth pressure under static and cyclic vertical surcharges in three different conditions of wall movement such as translation (T), rotation about the bottom (RB) and rotation about the top (RT) have been studied using popular Geotechnical software 'FLAC' based on finite difference method. In order to verify and calibrate the numerical model, some tests in passive case were carried out using the physical model of a retaining wall developed in "soil mechanic laboratory of civil and environmental engineering faculty at Amirkabir University of Technology (Nikkhah & Mirhosseini, 2004)". Finally, parametric studies have been done to investigate the effect of soil properties, type and amount of wall movements and also the nature of surcharges on passive earth pressure.