Optimal geotechnical site investigations for slope reliability assessment considering measurement errors

Site investigation is an important step of geotechnical projects. Previous studies have investigated the benefits of undertaking site investigation for differing scopes by assuming the measurements obtained from site investigation tests are “true” measurements without measurement errors. However, measurement errors are inevitable in all types of site investigation testing methods which cannot be neglected. This paper attempts to quantify the effects of measurement errors on the optimal number of site investigation tests and optimal testing methods. Monte Carlo simulations, random field theory and Kriging fitting method are utilised to incorporate the uncertainties due to soil variability and measurement errors in the slope reliability analysis process. Results indicate that there are significant benefits from increasing the number of site investigation tests in terms of the risk reduction of slope design. By taking the cost of site investigation into account, the optimal number of site investigation tests can be identified by balancing the risk and the cost.