Prediction and performance of single piles in clay soils under vibratory loadings.

摘要

This study developed a model for predicting the response, in terms of amplitude versus frequency of single piles under lateral vibratory loadings embedded in clay or fine silty soils. The model incorporates frequency dependent parameters and the effects of soil non-linearity through the relationship between soil shear modulus and damping with strain. A computer program, Dyna5, was used to generate the computed response of single piles using the Novak and EI-Sharnouby (1983) approach. Soil non-linearity was accounted for by incorporating spline interpolation routine into Dyna5. Sliding and coupled rocking vibrations were addressed. The computed responses were predicted and compared with the measured data in terms of resonant amplitudes and resonant frequencies. The computed responses show higher natural frequencies and lower resonant amplitudes than those determined from field tests. That difference is mainly due to overestimated soil shear modulus and damping used in the computations. For that reason, full-scale tests of single piles under lateral dynamic load were extensively analyzed to develop the range of reduction factors on soil shear modulus and total damping until the predicted and the measured amplitudes and frequencies match. Then, through a regression analysis these reduction factors were correlated with properties of the soils and piles. Empirical equations relating the reduction factors with soil shear strain, elastic properties of soils and piles, and pile geometry are proposed and validated using different sets of experimental tests. It is concluded that the model predicts the single pile dynamic response satisfactorily.