ANALYTICAL SOLUTION FOR MODEL OF PILE HAMMER IMPACT
打桩锤击模型的解析算法

The drivability study of piling requires modeling of the hammer impact to calculate the input force wave at the pile head. This force wave can be computed numerically or by simple analytical solutions. Analytical solutions are presented for hammer impact considering a model which uses lumped mass for the ram and anvil,a spring and a dashpot for the anvil cushion,and another spring for the cap cushion on the top of a pile. The pile is modeled as a dashpot. The solutions account for the separation of the anvil mass from the pile cap cushion as well as the separation of the ram mass from the anvil cushion. The developed solutions are used to perform a parametric study to show the influence of the pile cushion and the mass ratio of pile cap to pile hammer on the maximum force transmitted to the pile head. The parameters of pile cap cushion are achieved by laboratory static test. Force-time responses derived from the analytical model are compared with field data,which indicate well consistent with each other.