WaiChing Sun, Columbia University
The hydro-mechanical responses of geological materials, such as soil and rock are strongly influenced by the environmental they subjected to. In cold region, the ice crystals in the void space may introduce many interesting multi-physical behaviors, such as creeping, thermal-induced hardening/softening and freeze-thaw action responsible for sharing the earth surface features and the mobility of vehicles. This talk focuses on the multiscale modeling techniques for predicting those thermos-hydro-mechanical behaviors developed by my research team and supported by the ARO Earth Materials and Process program. In particular, we will discuss (1) a finite strain finite element model that captures the freeze-thaw action of frozen soil, (2) multiscale techniques used to link grain-scale simulations to macroscopic micro-polar continua models, and (3) a new class of constitutive-law-free model that enables predictions made directly from experimental or simulated data based on spectral decomposition. Spurious pathological predictions by previous DEM-FEM models are examined and the remedies are proposed. Preliminary validation with experiments for the temperature- and rate-dependent behavior of frozen soil will also be discussed.
WaiChing Sun is an assistant professor in the Department of Civil Engineering and Engineering Mechanics at Columbia University, New York. From 2011 to 2013, he served as a senior member of technical staff at Sandia National Laboratories. Professor Sun works in the fields of theoretical and computational poromechanics with a special emphasis on geomechanical applications. His research includes multiscale modeling porous media, multiscale verification and validation with CT images, digital rock and granular physics, applications of mathematical tools, such as graph theory, Lie algebra for modern engineering problems. He has published more than 40 peer-reviewed articles. He received the Dresden Fellowship in 2016, US AFOSR Young Investigator Program Award in 2016, US Army Young Investigator Program Award in 2015, and the Caterpillar Best Paper Prize in 2013. Dr. Sun holds BS degree from UC Davis (2005), MS degrees from Stanford (2007) and Princeton (2008) and PhD degrees from Northwestern (2011).