On the Validity of Miner’s Rule and Its Application in Offshore Pile Design Practice

Abstract

Current design practice simplifies complex loading scenarios, i.e. highly cyclic loads from varying direction offshore, using classification methods by combining different cycle packages with constant frequency, mean load level and amplitude. This procedure assumes the resulting accumulated deformation in the soil to be independent of the ordering of the cycle packages, i.e. the validity of miner’s rule. This paper presents an experimental study on the validity of Miner’s rule in non-cohesive soils based on high cyclic direct simple shear tests. The test program comprises monotonic and high cyclic direct simple shear tests in fine silica sand, which is routinely used at Centre of Offshore Foundation Systems. The paper investigates the effect of ordering of the cycle packages on the resulting cyclic deformation accumulation for different loading scenarios with varying mean and cyclic load level. The results are evaluated in terms of the accumulated volumetric and the resulting shear strain. Based on the literature, Miner’s rule is assumed to be valid for a deviation of the relevant variables of < 20 %. Conclusions with respect to the influence of cyclic preloading are drawn and related to current design practices.