THE CONTROL OF STEEL PIPE PILE DRIVING BASED ON RELIABILITY ANALYSIS OF BEARlNG CAPACITY ESTIMATION

Abstract

The ultimate bearing capacity of steel pipe piles consists of skin friction and end resistance, and it is highly desirable that it be estimated independently during the pile driving procedure. Such an estimation becomes possible by using the method based on wave theory. The main objective of the present study is to provide a probabilistic method for pile driving control, in which the skin friction term and the end resistance term are independently estimated. The paper presents following the two results : Firstly, indices of ultimate bearing capacity to stop pile driving are determined based on reliability analysis. The ultimate bearing capacity, which is needed to stop pile driving, should be changed to about 80.0(%) to 120.0(%) of the value in a usual design method, according to the ratio of the skin friction term to the ultimate bearing capacity. Secondly, a method is introduced based on Bayes' theorem, in which information obtained from in-situ pile loading tests is applied to the proposed reliability analysis. For friction piles, the ultimate bearing capacity, which is needed to stop pile driving, should be changed to about 40.0(%) to 120.0(%) of the standard value in the case where in-situ loading tests are not available. This should be in accordance with the observed set-up value of skin friction of six to one in the in-situ pile loading tests, respectively.