Seismic Earth Pressure Development in Sheet Pile Retaining Walls: A Numerical Study

TL;DR

This study evaluates the accuracy of the Mononobe-Okabe method for predicting seismic earth pressures on sheet pile retaining walls using a finite element model, highlighting its limitations and applicability.

Contribution

It provides a numerical assessment of the Mononobe-Okabe method's reliability in seismic conditions for sheet pile walls, comparing it with detailed finite element simulations.

Findings

M-O method often underestimates dynamic earth pressure

Point of application of seismic force differs from static case

Recommendations for improved seismic earth pressure estimation

Abstract

The design of retaining walls requires the complete knowledge of the earth pressure distribution behind the wall. Due to the complex soil-structure effect, the estimation of earth pressure is not an easy task; even in the static case. The problem becomes even more complex for the dynamic (i.e., seismic) analysis and design of retaining walls. Several earth pressure models have been developed over the years to integrate the dynamic earth pressure with the static earth pressure and to improve the design of retaining wall in seismic regions. Among all the models, MononobeOkabe (M-O) method is commonly used to estimate the magnitude of seismic earth pressures in retaining walls and is adopted in design practices around the world (e.g., EuroCode and Australian Standards). However, the M-O method has several drawbacks and does not provide reliable estimate of the earth pressure in many instances. This study investigates the accuracy of the M-O method to predict the dynamic earth pressure in sheet pile wall. A 2D plane strain finite element model of the wall-soil system was developed in DIANA. The backfill soil was modelled with Mohr-Coulomb failure criterion while the wall was assumed behave elastically. The numerically predicted dynamic earth pressure was compared with the M-O model prediction. Further, the point of application of total dynamic force was determined and compared with the static case. Finally, the applicability of M-O methods to compute the seismic earth pressure was discussed.