Page - 871 - in Book of Full Papers - Symposium Hydro Engineering

SUMMARY To a great extent, an accurate prediction of the bearing capacity is considered to be a common practice in geotechnical engineering. Analysis and design of geotechnical structures continue to face with many uncertainties which make it difficult to choose the design parameters. Mostly, the uncertainties are pertinent to unreliable deterministic soil characteristics. Use of a deterministic approach for soil specifications may result in either underestimation or overestimation of the soil shear strength in problems dealing with limit loads. Therefore, the traditional deterministic limit load methods, e.g. the conventional limit analysis and slip line methods could not capture a reliable estimation of the bearing capacity. In order to examine the parameters involved in the estimation of bearing capacity of foundations, it is required to take in to account the uncertainty nature of the soil to perform the reliability analysis. In the analysis, the effect of probabilistic input parameters on the limit loads is considered. As a matter of fact, the reliability analysis makes it possible to be able to quantify the uncertainties involved. In this study, the reliability analysis of the bearing capacity of dam foundations was carried out via Monte Carlo simulation with the focus on the uncertainty associated with the friction angle. To do so, the upper-bound limit analysis was employed assuming the deterministic friction angle. The formulation and the general computational procedure were kept exactly as the one introduced by Michalowski (1997). As it is obvious, the non-associativity of plastic deformation of soils is a significant factor in limit load problems. In the current study, the substantial influence of the dilatancy angle on 𝑁 𝛾 was also examined. As a conclusion, appropriate safety factors based on reliability analysis are suggested leading to economical advantage of the design of geotechnical structures. KEYWORDS ANALYSIS DAM FOUNDATION PLASTICITY SAFETYFACTOR 871