The use of 3D LE methods to calculate slope stability during strong earthquake shaking

Abstract

This paper discusses the application of three-dimensional (3D) limit equilibrium (LE) analysis for slope stability, with a focus on seismic considerations. While traditional 2D limit equilibrium analyses have been extensively used in civil and mining engineering, the emergence of 3D methods offers enhanced capabilities. The paper reviews the use of seismic coefficients and pseudostatic analyses to evaluate the impact of earthquakes. We discuss the theoretical foundations of limit equilibrium analyses, and introduce TSLOPE software, specifically designed for 3D LE analysis. A case study of the slope at the Waiau tank farm following the 2016 Kaikōura earthquake illustrates the practical application of 3D LE analysis. The study compares results from 2D and 3D analyses. We conclude that the 3D approach yields more accurate and reliable results, particularly in slopes with constraining geometry or irregular loading. The authors advocate for the increased use of 3D methods in slope stability analyses, rather than relying on traditional 2D LE methods. Recommendations include comprehensive guidance from NZ Geotechnical Society, further research on seismic coefficients, and the compilation of local case studies for calibration. The paper concludes by highlighting the opportunity to advance seismic design practices and achieve economic slope reinforcement through the adoption of 3D LE analyses.