DYNAMIC RESPONSE ANALYSIS OF REINFORCED EARTH WALL USING PLAXIS 2D

Abstract

As compared to static behaviour, the seismic behaviour of retaining wall is quite complex. The backfill behind the wall is a responsible factor for the wall movements and the pressure on the wall. The inertial and flexural response of the wall is also responsible for those complexities. The nature of the dynamic load is a deciding factor for the seismic stability of retaining walls. The seismic response of the soil wall system increases because the backfill soils move out of phase with the foundation soil and cause deflections of different parts of the wall. The deflection can be significant and depends on the intensity of the earthquake. Due to complexities like interacting phenomena, inherent variability and uncertainty of soil properties, it is not currently possible to analyze all aspects of the seismic response of retaining walls accurately. As a result, simplified models that make various assumptions about the soil, retaining structure and input motion are most used for seismic design of retaining walls. The evaluation of earth pressures at the wall-backfill interface continues to be a technical challenge. Problems can be solved analytically using pseudo-static, pseudo-dynamic and modified pseudo-dynamic approaches. The pseudo-static approach considers the seismic loading induced by earthquakes to be time-independent and assumes that the magnitude and phase of acceleration are uniform throughout the backfill. The pseudo-dynamic approach accounts for the influence of phase difference over the height of the wall and considers the seismic behaviour of soil and its interaction with earthquake waves. To overcome the limitation of the prior approaches to address the real behaviour of reinforced earth walls modified pseudodynamic approach can be proposed as a visco-elastic soil model, which incorporates the more accurate behaviour of soil and simulates the close to real response of reinforced structure during the seismic event.