Dr.  Tahar Ayadat is an Associate Professor of Civil Engineering at Prince Mohammad Bin Fahd University (PMU), Al Khobar, Saudi Arabia. Dr. Ayadat earned his PhD in Civil Engineering from Sheffield University, England in 1991. His major expertise is in the area of geotechnical and geo-environmental Engineering. Dr. Ayadat has about 28 years of academic and practical experiences in conducting design, analysis, inspection, expertise and management of various projects. He has published more than 85 papers and technical reports in refereed journals and international conference proceedings. He supervised and co-supervised many MSc and PhD theses. Dr.  Ayadat is currently registered Professional Engineer (PEng) in the Province of Quebec, Canada. He has also been a member of the Canadian society of civil engineering since 2004. Dr. Ayadat’ current research interest includes behavior of unsaturated and difficult soils, and foundations design on problematic soils; design/performance of stone column foundations, pile foundations and soil anchors; numerical and analytical investigations on deterioration of highways and roadways flexible pavements; slope stability problems; instrumentations, methods and procedures for laboratory/field soil testing; extraction of contaminant from soils, stabilization of contaminated soils, waste management, and stability of sand-betonies liners. He developed several theories for designing anchors, reinforced earth and single/group of stone column foundations, proposed many empirical formulae for predicting collapsible soils, and developed a mechanism concerning the causes of soil collapse