For the design of pipe foundation of large-span bridge, in-situ loading test on the deep Pleistocene clay layer was carried out. The loading plate, the diameter of which was 250mm, was placed on the Pleistocene clay layer at 70 m depth utilizing the bore hole. The settlement was observed for 9 months, in which the step loading was given by the hydraulic jack. Measured settlement showed the periodic fluctuations related with the tidal change, and the settlement continued with time and the

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... y of convergence was not shown within the 9 months. The compression strain of Pleistocene clay calculated from the measured settlement was almost same as that predicted from the consolidation yield stress and coefficient of secondary compression obtained from laboratory test of undisturbed samples. The settlement-time relationship of in-situ loading test was explained by the numerical analysis in which Cam-Clay model was used for the Pleistocene clay layer. Key words:in-situ loading test, Pleistocene clay,coefficient of secondary compression,consolidation yield stress, overconsolidation