Lacasse Lecture

Abstract
Uncertainty inevitably exists in the constructed engineering geological model (herein referring to stratigraphic configuration and associated geo-properties). Substantial efforts have been devoted to characterizing the geo-properties uncertainty and assessing its effects on the performance and design of geotechnical systems. In contrast, studies on the characterization of stratigraphic configuration and its impact are limited. This paper reviews and discusses the progress achieved in the regional and site-specific characterization and assessment of engineering geological model uncertainty, focusing on the stratigraphic model uncertainty. To this end, uncertainties involved in the geological data and engineering geological model construction are discussed first, followed by a review of the methods available for the stratigraphic model uncertainty characterization. Then, probabilistic methods commonly used to assess the impact of the stratigraphic model uncertainty are introduced, and case studies are presented to depict the effects of the geological model uncertainty on the performance prediction and design of geotechnical systems. Finally, challenges and recommendations for future research are discussed.

Biography
Dr. Hsein Juang is an emeritus professor at Clemson University after 36 years of academic service. Dr. Juang also served as a chair professor and Yushan Scholar at National Central University (2018-2021) after his Clemson career. He earned his BS (1974) and MS (1976) degrees from National Cheng Kung University and a PhD degree (1981) from Purdue University. Dr. Juang has received many awards, including the GEOSNet Distinguished Award 2022, the Wilson Tang Lecturer 2019, the GEOSNet Award 2015, and the TK Hsieh Award 2001 by the Institution of Civil Engineers (ICE). Among his career achievements, Dr. Juang is most pleased with being selected by his students as the Outstanding Teacher and graduating 22 doctoral students at Clemson University. Dr. Juang has served the geotechnical profession in various capacities, including the chair of the ASCE/GI RAM committee (2009-2012), the conference chair for the ASCE Georisk 2011, and the Editor in Chief for Engineering Geology (2012-2024). Dr. Juang has made many original contributions to soil liquefaction, supported excavation, reliability-based methods, and robust design.