Reduction and Degradation of Stiffness

Typical stress-strain hysteresis loop. (After Idriss, I.M. et al., /. Geotech. Eng. Div., 104,1427-144 1978. Reprinted with permission of ASCE.) 

OCR is the overconsolidation ratio a is the mean principal effective stress k is the a constant value which depends on PI, as given below Gn,a is the maximum shear modulus is the atmospheric air pressure 

This equation, however, is said to produce low values for void ratios in excess of 2. 

Reference strain for clays. (After Hardin, B.O., and Dmevich, V.P., /. Soil Mech. Found. Div., 98, 667-692, 1972. Reprinted with permission of ASCE.) 

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Sections 9.4.1 through 9.4.3 discuss about (1) strength determination, (2) pore pressure build-up, and (3) reduction and degradation of stiffness. 

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