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Intergrain contact density indices for granular mixes ¡ª I:FrameworkS. Thevanayagam Dept. of Civil, Struct. and Envir. Eng., State University of New York, Buffalo, NY 14260, USA Abstract:
Mechanical behavior such as stress-strain response, shear strength, resistance
to liquefaction, modulus, and shear wave velocity of granular mixes containing
coarse and fine grains is dependent on intergrain contact density of the soil.
The global void ratio e is a poor index of contact density for such soils. The
contact density depends on void ratio, fine grain content (CF), size disparity
between particles, and gradation among other factors. A simple analysis of a
two-sized particle system with large size disparity is used to develop an
understanding of the effects of CF , e, and gradation of coarse and fine grained
soils in the soil mix on intergrain contact density. An equivalent intergranular
void ratio (ec)eq is introduced as a useful intergrain contact density for soils
at fines content of less than a threshold value CFth. Beyond this value, an
equivalent interfine void ratio (ef)eq is introduced as a primary intergrain
contact density index. At higher values of CF beyond a limiting value of fine
grains content CFL, an interfine void ratio ef is introduced as the primary
contact density index. Relevant equivalent relative density indices (Drc)eq and
(Drf)eq are also presented. Experimental data show that these new indices
correlate well with steady state strength, liquefaction resistance, and shear
wave velocities of sands, silty sands, sandy silts, and gravelly sand mixes.
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