AN ANALYTICAL SOLUTION TO LONGITUDINAL VIBRATION OF A PILE OF ARBITRARY SEGMENTS WITH VARIABLE MODULUS

The vibration problem of a pile of arbitrary segments with variable modulus under exciting force is established, in which the influence of the soil under pile toe and the surroundings is taken into account. With Laplace transforms, the transmit functions for velocity and displacement of pile are derived. Furthermore, in terms of the convolution theorem and inversed Laplace transform, an analytical solution for the time domain response of a pile subjected to a semi-sine impulse is developed, which is the theoretical basis of the sonic method in pile integrity testing. Based on the solution, the vibration properties of pile with sharp or continuous modulus are studied. The validity of this approach is verified through field dynamic tests on some engineering piles. It shows that the theoretical prediction and the response of the pile are in good agreement.