Cohesive Soil Behavior Under Random Excitation Conditions
A testing program was undertaken in which cohesive soil at different confining pressures was tested in a resonant column device using random torsional excitation in addition to conventional sinusoidal excitation. The damping and shear modulus from random loading testing were determined by both the power spectral density function and the transfer function method. Evaluation of the dynamic soil properties for sinusoidal vibration followed conventional procedures. The results indicated that during random loading, the damping values were higher and the shear moduli lower than the values obtained from sinusoidal loading at the same root mean square strain. For the cohesive soil tested, formulas were developed to correct the damping and shear moduli obtained from routine sinusoidal testing so that the values are more representative of actual field conditions during random dynamic loading.