Importance of small strain response to prediction of large scale behavior in sand

All strain hardening/softening elasto-plastic constitutive models include some measure of plastic stiffness (which is related to hardening). Plastic stiffness, similar to elasticity, is related to soil fabric and is therefore difficult to measure for sand and silt in the laboratory due to the inherent problems in obtaining undisturbed samples. Unlike elastic shear modulus which is now routinely determined in situ from shear wave velocity measurements, plastic hardening is also difficult to determine in situ as soil response to plastic hardening and density can be difficult to differentiate. Utility exists bra methodology that can determine plastic hardening in situ. This paper considers that hypothesis that, similar to observed for clays, plastic stiffness of sands and silts is correlated to elastic stillness. Preliminary results on three natural soils are encouraging, and suggest a linear relation between elastic shear modulus and plastic hardening exists.