Load-settlement analysis for bored piles using hyperbolic transfer functions.

A practical method for analyzing the load-settlement behaviour of bored cast-in-place plies has been proposed. The method employs Kondner-type hyperbolic load-transfer functions, by which non-linear behaviour can be simulated plainly and simply, for skin resistance and end resistance. The parameters required may be determined from the results of usual in-situ and/or laboratory tests. The procedure for determining the parameters is discussed in detail : It is indicated that displacements needed to mobilize half of the ultimate skin resistance are as small as 1/100 of those of the ultimate end resistance. One-dimensional finite element formulation, which personal computers are enough to solve, for the model proposed is described. Analytical results of loading tests for large-diameter bored piles are discussed. The method proposed may be useful for the following situations : the preliminary analysis for planning an appropriate loading-test program and the back analysis of loading tests for optimizing the design.