THE LATERAL IMPEDANCES OF SINGLE PILE AND PILE GROUPS IN LAYERED SOILS

With the hypothesis of "beam-on-Winkler foundation", the vibration differential equations of single pile in different soil layers are established. Combining with the continuum condition of pile between different soil layers and boundary condition of pile on the top and bottom, solution of the differential equations is obtained. The single pile impedance and dynamic interaction factor are used to calculate the impedance of pile group. An approximate method for calculating those impedances is also proposed. In this method, layered soils are replaced by an equivalent homogeneous soil. The parameters of equivalent homogeneous soil are obtained by energy-conservation principle and the deflection figure of pile induced by lateral static load at pile top. Finally, some useful conclusions are presented through theoretical analysis of practical problems.