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Investigating micro-mechanical origin of liquefaction

Utkarsh Mital (Caltech), Jose Andrade (Caltech), Sergio Torres ()

Multiscale Mechanics of Particulate Media

Mon 2:40 - 4:00

Sayles 105

The state-of-the-art developments in liquefaction have treated this instability as a macroscopic phenomenon. Yet, we know that the behavior of granular media is fundamentally encoded at the grain scale. It is processes at the grain scale that manifest themselves collectively and control behavior at the macroscale. Hence, in order to truly understand liquefaction, a micro-mechanical analysis of this devastating instability is warranted. What is the microscopic signature of liquefaction? What characterizes liquefaction at the grain scale? What causes a looser than critical sample to liquefy? This contribution describes some preliminary work done to that effect. We analyze data obtained from DEM simulations of an undrained triaxial cell. Of particular interest is the behavior of sample at the onset of liquefaction instability. Recognizing the fact that the strain accumulated in the sample till the onset of instability is relatively small, we have established a micro-mechanical version of the liquefaction instability criterion . Our science question now is to understand the physical meaning of this micro-mechanical criterion. Some potential avenues that we explore include the bimodal nature of force transmission and anisotropy of the granular system. Our long-term objective is to then be able to link the micro-mechanical properties of granular systems to macroscopic quantities. This would in turn transform our understanding of liquefaction as a multiscale phenomenon propagating from the grain-scale.