Characteristic estimate of pile bearing capacity from pile load tests on socketed drilled shafts in weathered rock

Abstract

Realistic estimate of pile capacity can be obtained from the results of pre-construction pile load tests conducted on non-working piles. Estimated pile bearing capacity from this sort of pile load tests can be exploited to refine the preliminary pile design and may allow for confidently reduced safety factors. In some cases, however, the results obtained from a number of conducted pile load tests in the same site may be quite variable, probably due to spatial soil variability. In such a case, a characteristic estimate of pile capacity from the variable pile load test results is needed. A decision-making algorithm is, therefore, required and that is generally governed by the uncertainties in the decision variables and the risk-level. In this paper, different decision-making tools are examined to determine a characteristic estimate of pile bearing capacity from a set of pile load tests with variable results. The approach of associating the characteristic estimate of pile capacity with the risk-level is appraised. A case study is implicated that comprises results of 12 compression pile load tests carried out in a certain project site in China. The tested piles were non-working drilled shafts socketed in weathered tuff.