Soil Dilation and Shear Deformations During Liquefaction

Recent records of seismic site response have documented a salient liquefaction-induced cyclic shear-deformation mechanism. During liquefaction, these ground acceleration records have suggested a possible strong influence of soil-skeleton dilation at large cyclic shear strain excursions. Such phases of dilation can result in significant regain in shear stiffness and strength, leading to: i) associated instances of pore-pressure reduction. ii) appearance of spikes in lateral acceleration records (as a direct consequence of the increased shear resistance), and iii) a strong restraining effect on the magnitude of cyclic and accumulated permanent shear strains. As presented in this study, these response effects are also thoroughly documented by a large body of experimental research (mainly employing clean sands and dean non-plastic silts), including centrifuge experiments, shake-table tests, and cyclic laboratory sample tests. A number of efforts to computationally simulate this aspect of soil behavior are presented. In addition, the framework for a newly developed computational model is discussed