Dr. Majid Ghayoomi is a Professor in the Department of Civil and Environmental Engineering at the University of New Hampshire. In the last 15 years, he has worked on several projects involving the application of unsaturated soil mechanics and hydro-geo-mechanics of soils in different geotechnical applications including soil-structure interaction, seismic response of geotechnical systems, flooded roads, and coastal infrastructure. He has also worked on projects dealing with climate and seismic resilience and adaptation of coastal and Arctic infrastructure and social systems. Dr. Ghayoomi currently serves as the secretary for the ASCE Unsaturated Soils committee. He received the 2014 ISSMGE TC106 Award for the best paper in the application of unsaturated soils, the 2018 ISSMGE Unsaturated Soils Spark Bright Lecture Award, and the 2022 UNH CEPS Excellence in Research Award. Dr. Ghayoomi is a licensed professional engineer in the state of New Hampshire.
Soil-Foundation-Structure Interaction (SFSI) evaluates the collective seismic response of a system containing the superstructure, foundation, and surrounding soil given the earthquake motion at the ground surface. During an earthquake, the seismic motion propagates upward and changes in characteristics, passing through the bedrock and layers of soil before reaching the soil surface and influencing the structural system through its foundation. Thus, understanding this complex interaction will be crucial in evaluating the extent of variations in motion amplitude, frequency content, and duration, as well as in assessing the overall performance of the structural system. The dynamic characteristics of soils not only affect the seismic ground response but also greatly influence SFSI. They impact the motion transferred to the foundation through the soil-foundation interface, change the flexibility and natural frequency of the system related to soil-foundation stiffness and damping, and alter seismically induced settlements. The behavior of unsaturated soil is complex and differs from dry and saturated soil deposits because inter-particle suction stresses increase the effective stress and change dynamic characteristics of soils. Although the water table level prior to a seismic event may not be known, understanding the potential impact of moisture variability and the extent of this uncertainty would be extremely critical in improving SFSI analysis procedures and predicting and mitigating detrimental earthquake effects. This presentation reviews a campaign of centrifuge and analytical modeling aimed to study the role of ground water level and unsaturated soil profile on seismic site response, soil-structure interaction, foundation settlement, and the response of rocking foundations for bridge systems.