A role of pile load test - Pile load test as element test for design of foundation system

This paper discusses the roles of load tests in construction sites of pile foundations in terms of construction control or quality assessment of constructed piles, and the use of pile load test results in design of foundations structures, based on the authors' limited experiences. Firstly, the factors of safety for single piles employed in various Countries are reviewed to discuss rational reduction of the factor of safety according to the number of load tests in a pile construction site. Secondly, variation of pile capacities of the piles with the same configuration in a relatively narrow area is presented to discuss the need of conducting load tests on all the constructed piles. Thirdly, features of various pile load test methods are reviewed to discuss possible increase in the number of load tests in a site in cost and time effective manner. Fourthly a rapid load test method, called Spring Hammer test method, is introduced with their applications to a site. Finally, use of results of a pile load test on single piles for deformation analyses of a piled raft foundation is introduced to demonstrate that conducting pile load test as element test in a site give us a great benefit in design of foundation systems.