Designing Foundations with Piles for Vibrating Machinery

Abstract

CP 2012 is used extensively throughout the world to design machine foundations for vibrations. The code, however, does not give practical advice on how to design a foundation with piles. CP 2012 models the soil as a system of undamped individual springs. A pile group may similarly be modelled as a system of springs, determined from the geometric and material characteristics of the piles. The stiffness of a pile group is expressed in the same form as sub-grade reactions, permitting the use of the same dynamic equations given in CP 2012; thus, the code may be used for both cases— soil and piles. The theory described in this paper is based on structural stiffness theory. Several assumptions are therefore made concerning the soil characteristics, effective length and boundary conditions of the pile. The derivation of the equations are given and compared to a simple finite element model.