A filtering method for cone penetration test end resistance (qc) data has recently been developed to assist liquefaction analysis of thin sand layers. The method was calibrated using existing experimental and numerical research and allows for the influence of the penetrometer diameter on the sensing distance and development length as well as on the relative strength of layers in the vicinity of the cone. The approach is used in this paper to estimate the end bearing resistance of a cone with the same diameter as a (closed-ended) pile, qp. This resistance is then compared with the end bearing measured in a database of instrumented static load tests. The paper shows that the end bearing measured at a pile displacement of 10% of the pile diameter (qb0.1) is directly proportional to qp. The approach is shown to provide a rational and consistent means of determining pile end bearing that is an improvement on existing CPT-based design methods.
Eduardo Bittar, Barry Lehane, Ross W. Boulanger and Jason T. DeJong
Keywords: base resistance, closed-ended piles, layered soils, cone penetration test (CPT)
Publisher: DFI