Experimental and numerical investigation of dynamic rocking foundation behavior

Phipps, Jacob
Major Professor
Jeramy C. Ashlock
Sri Sritharan
Committee Member
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Civil, Construction, and Environmental Engineering

Soil-structure interaction problems have long been a focus of researchers over a wide array of applications. Presented in this thesis are experiments and analyses of small-strain soil-structure vibration problems and large-strain soil-structure rocking behavior. A literature review is presented regarding the relevant bodies of work for both topics followed by two experimental investigations. The first is an investigation of multi-modal, small-strain vibrations of field-scale surface foundations on a natural cohesive soil deposit. For this investigation, the physical aspects of the soil-structure vibrating system, the excitation system, the measurement system, the measurement approach, numerical modeling, and comparison with experimental results are presented. The validity and efficiency of a hybrid-mode vertical-eccentric test is demonstrated via its equivalence to separate modal vertical and lateral-rocking tests. Critical insights from numerous past centrifuge scaled-model studies are verified and extended to this field-scale study. The second is an experimental investigation of large-strain rocking of a field-scale surface foundation resting on a cohesive soil deposit. The physical aspects of the soil-structure rocking system, the measurement system, the various actions imposed on the physical system, and a discussion of the experimental results are presented. The results of the field investigation show that energy may be dissipated at the soil-structure interface by means of soil hysteresis through moment-rotation and horizontal force-horizontal displacement. Rounding of the soil surface was observed due to yielding and plastic deformation of the soil from increased rotational strains. Yielding soil also introduced nonlinearity into the response of the soil-foundation system, which directly influenced the period. Lastly, an analytical model was developed to satisfactorily simulate dynamic properties of a rocking system from quasi-static experimentation.