Reliability issues and future challenges in geotechnical engineering for offshore structures

The paper describes the role of reliability analysis in the geotechnical design of offshore structures, and attempts to put in perspective the interrelationship and dependence of the geotechnical aspects to related fields of offshore engineering. Predictions of foundation behaviour and soil-structure interaction cannot be made with certainty due to the spatial variation of soil properties, limited site exploration, limited calculation models, uncertainties in soil parameters and uncertainties in loads. It is increasingly important to adopt rational and {open_quotes}documentable{close_quotes} design approaches that inform about and account for the uncertainties in the analysis parameters. Reliability analysis enables one to map and evaluate the uncertainties. With the reliability tools available today, it is possible to establish, without too much difficulty, a probabilistic model for an existing deterministic solution. Probabilistic analyses are a useful addition to, and not a replacement of, deterministic analyses. That one finds it difficult to quantify the uncertainties is not a reason to omit defining them or establishing their significance on the quantities predicted. Future challenges and expected trends within offshore geotechnics are also highlighted.