Increase in Pile Capacity with Time in Missouri River Alluvium

Abstract

The data measured in this study suggest that the increase in compressive pile capacity for a 42-ft long, HP14x102 pile, in a predominantly fine-grained Missouri River alluvium soil profile, increases by about 16 percent from days seven to forty-four after driving. It appears evident that Davisson’s (1973) failure criteria seems to agree fairly well with the observed plunging failure of two compressive pile-load failure tests performed in Missouri River alluvium. By comparison of compressive proof and failure tests performed on day forty-four after driving, it appears that loading a pile to some degree prior to failure, and then reloading the pile, has almost no affect on the load-settlement relationship. Hence, proof loaded piles in Missouri River alluvium that pass should be allowed for use beneath the structure. Finally, comparisons of tension and compression pile load test data have lead to two possible conclusions. First, the estimation of tip load by tell-tale data may not be accurate, and may underestimate the amount of load actually transferred to the tip. And second, it seems viable that, at this site, the skin friction that can be counted on in design is perhaps 55 to 60 percent of that calculated for compression

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