EXPERIMENTAL STUDIES OF FORCES ON PILES

J. R. Morison, J. W. Johnson, M. P. O'Brien

Abstract


In the design of a pile structure exposed to surface waves of a given height and period, some of the factors involved in the problem and studied herein are the size, shape and spacing of the piles and the moment distribution on uniform and non-uniform piles. Theoretical and experimental investigations have shown that the force exerted by surface waves on a pile consists of two components — a drag force and an inertia force. The drag force is proportional to the fluid density, the projected area and the square of the fluid particle velocity. The inertia force, including the virtual mass, is proportional to the fluid density, the volume of the object and the fluid particle acceleration. The virtual mass is the apparent increase of the displaced mass of fluid necessary to account for the increase in force resulting from the acceleration of the fluid relative to the object. This factor is included in the coefficient of mass term in the force calculations.

Keywords


pile design; laboratory testing; field testing

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