Effect of subsidence on the stability analysis of submarine slopes using the enhanced limit equilibrium method

Abstract

Human activities in the subsea environment, particularly oil and gas extraction, rank among the most important economic activities in the modern world. However, this process can reactivate faults, causing subsidence, and consequently modifying the natural conditions of submarine slopes and their stability. Therefore, this paper aims to evaluate the effect of subsidence on the stability of submarine slopes under drained and undrained conditions. The Enhanced Limit Equilibrium Method (ELEM) was applied to slopes with steep angles and geotechnical parameters representative of subsea environments, considering subsidence with varying shapes and magnitudes. The results indicate that undrained conditions are the most critical due to the increase in pore pressure caused by subsidence and reduction in shear strength. Changes in the slope’s steep angles influence pre-subsidence stability and the evolution of post-subsidence Factor of Safety (FS) under undrained condition. Variations in subsidence levels and steep angles made it possible to determine the critical subsidence leading to slope failure under the initially defined geotechnical conditions. This study contributes to a better understanding of the impact of subsidence on the stability of submarine slopes and can guide future analyses, increasing safety for offshore structures.