Review of an Electrical Method for Evaluation of Stress Ratio Required to Cause Liquefaction and Dynamic Modulus

Abstract

In the classical liquefaction and site response analyses of saturated granular deposits, in situ parameters such as dynamic shear modulus and stress ratio required to cause liquefaction are required. The in situ state of soil can only be captured by field methods as it is difficult to obtain undisturbed samples in granular deposits. In situ density alone cannot be used to evaluate liquefaction characteristics for soils as it has been shown that liquefaction characteristics of soils are influenced not only by the density of soil, but also by the shape and structural arrangement of the soil particles. Parameters such as average formation factor, anisotropy index, and average shape factor, which are based on electrical conductivity of soil deposits measured in two directions, have been shown to relate to maximum dynamic shear modulus and stress ratio required to cause liquefaction. An electrical probe has been successfully used for the measurement of these parameters in the field. It has been verified using controlled laboratory tests and field predictions using the probe have been presented. This paper reviews the application of the methodology to the in situ prediction of the stress ratio required to cause liquefaction and dynamic shear modulus for the use in numerical procedures and evaluation of soil liquefaction.

Void distributions in samples of Ottawa sand

“…These techniques include photo-imaging analysis of assemblies of twodimensional (2D aluminum or photoelastic rods) (Oda andKonishi 1974, Matsuoka andGeka 1983), thin-section analysis (Oda 1972, Oda et al 1985, Frost and Kuo 1996, Kuo and Frost 1997, X-ray computed tomography (Lee et al 1992, Lee and Dass 1993, Desrues et al 1996, laser-aided tomography (Konagai et al 1992, Konagai andRangelow 1994), and indirect measurement of electrical resistance or wave velocity (Arulmoli andArulanandan 1994, Santamarina andCascante 1996).…”