Soil Behavior From Analysis Of Tests Of Uninstrumented Piles Under Lateral Loading

The most up-to-date method for the design of laterally loaded piles is to solve numerically the differential equation describing pile behavior. Iterative solutions are necessary since there is a nonlinear relationship between soil resistance and pile deflection. Curves giving soil resistance as a function of pile deflection, called p-y curves, have been the subject of research for a number of years. The development of p-y curves normally requires that a test be performed on an instrumented laterally loaded pile. A curve showing bending moment in the pile needs to be obtained for each of the applied loads. This curve can be differentiated twice to obtain soil resistance, and it can be integrated twice to obtain pile deflection. Cross plots of these values can be made at desired depths to obtain the p-y curves. This paper shows that nondimensional curves, developed from the numerical solutions of the differential equation, can be used to estimate p-y curves if only the following easily obtainable information is reported; pile properties, magnitude of the individual lateral loads, point of load application, deflection of the top of the pile, slope of the top of the pile, and condition of restraint (if any) at the top of the pile. Thus, there needs to be no instrumentation of the pile except above ground. The procedure is illustrated by applying it to a test reported in the literature.