Out of the 4 (four) widely accepted CPT-based pile capacity methods for offshore driven piles, for two of the methods - ICP and UWA methods - modifications have been suggested by researchers for application on calcareous sands. Unit shaft friction of piles driven through predominantly calcareous sand zones have been examined for 4 (four) piles which met refusal at 2 (two) sites in western Indian offshore. Values from "modified" CPT-based methods were compared with results of CAPWAP analysis. Study on the sites shows that 'modified ICP' and 'modified UWA' methods predict local shaft friction values that are generally lower compared to those obtained from CAPWAP analysis. Interestingly, the average unit shaft frictions over the length of the piles in sand predicted by individual CPT-based methods allowed by API (2007) for siliceous sands, are within about 30% of the values derived from CAPWAP.
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