Non-linear Lateral Pile Deflection Predictions in Clays

A method to predict lateral load-deflection relationships for single free-headed piles in clay, considering the non-linear modulus of the sub grade reaction is proposed on the basis of the analysis of full-scale test data on ten piles. The modulus of the horizontal subgrade reaction, k _h , was obtained from the field load-deflection data of six piles in soft clay and four piles in stiff clay. The k _h values depend on lateral (shear) strain, which is related to pile diameter and deflection. Empirical equations of normalized modulus degradation with shear strain have been proposed for both soft and stiff clays. The maximum value of the modulus of horizontal subgrade reaction, k _hmax , has been related with the undrained shear strength of clays. A comparison of the results from the present method and the p-y method with the measured load-deflection curves has also been made. The proposed method predicts upper and lower bound load-deflection curves which are valuable guides to making informed decisions.