This project will utilize the NEES equipment sites at the University of California at Davis, and at the University at Buffalo. The project will experimentally and numerically investigate the properties of resedimented soil following liquefaction, including void ratio distribution and shear strength. To investigate the properties of cohesionless soil subsequent to liquefaction, a series of coordinated physical model tests, numerical analyses, imaging analyses, and laboratory shear strength tests will be conducted. Physical model testing will include laboratory column testing, small- and large-scale shake table testing, and centrifuge testing. Numerical analyses will include .... (more)

This project will utilize the NEES equipment sites at the University of California at Davis, and at the University at Buffalo. The project will experimentally and numerically investigate the properties of resedimented soil following liquefaction, including void ratio distribution and shear strength. To investigate the properties of cohesionless soil subsequent to liquefaction, a series of coordinated physical model tests, numerical analyses, imaging analyses, and laboratory shear strength tests will be conducted. Physical model testing will include laboratory column testing, small- and large-scale shake table testing, and centrifuge testing. Numerical analyses will include simulations of the impact of non-homogeneities (as revealed by the physical model testing) on shear banding and the undrained shear strength of cohesionless soil, and novel computational fluid dynamics- (CFD-) based analyses of resedimentation of cohesionless soils. Laboratory testing will include shear strength testing on specimens recovered from the physical models, using special techniques to preserve their structure. Imaging will include bright field microscopy (BFM) and computer-aided tomography (CT) scanning of recovered specimens to evaluate their structure prior to and after liquefaction.

Uniform and non-uniform sands will be liquefied and allowed to reconsolidate at different stress levels. Solidified soils will be removed and freeze-dried for cutting into smaller samples. The heterogeneity of the smaller samples will be quantified through CT, BFM, and digital image processing (DIP). The numerical modeling program will utilize sedimentation theories and CFD implemented in Eulerian framework. The mathematical model will consist of three layers: clarified water, fully liquefied soil, and solidified soils. Shock fronts will be tracked using the volume of fluid (VOF) method. Two numerical modeling schemes will be pursued, the first aimed at predicting the heterogeneity of liquefied soils, and the second aimed at studying the effect of heterogeneity on the post-liquefaction strength. (hide)