An improved characterization model of liquefaction resistance by shear wave velocity for binary mixtures with consideration of coarse content

Abstract

This paper aims to develop an improved CRR-Vs1 characterization model for soil liquefaction evaluation for binary mixtures via a series of DEM simulations of drained monotonic tests, undrained cyclic tests and shear wave velocity measurements. The contributions of different contact types to the mean effective stress of binary mixtures depend mainly on the coarse content and to a negligible extent on the confining pressure and particle size ratio. The threshold coarse content, denoting the mechanical behavior transition of binary mixtures, can be identified either by the macroscopic evolutions of critical state lines or the distributions of microscopic contact forces. The skeleton reinforcement factor m decreases approximately linearly with the increase of coarse content, while the skeleton supporting factor b exhibits a nonlinear decrease relationship with coarse content, both of which are influenced by particle size ratio. Under the condition of the same equivalent skeleton void ratio, a Vs-correction function and a CRR-correction function are introduced to consistently describe the nonlinear coarse content effects on the shear wave velocities and liquefaction resistances of binary mixtures. The improved CRR-Vs1 characterization model with consideration of coarse content is established by relating the shear wave velocity and liquefaction resistance of binary mixtures to those of the base fine or coarse matrix using the concept of equivalent skeleton void ratio. Application of the proposed characterization model to real geotechnical materials requires laboratory element tests to determine the Vs-correction function and the CRR-correction function, together with the CRR-Vs1 benchmark curve of the base fine or coarse matrix.