Field testing of axially loaded piles in dense sand

Abstract

Large areas of the Netherlands are dominated by deep, soft soil deposits, posing a challenge to engineers with respect to the design of axially loaded foundations. The design of these foundations is primarily based on methods which use cone penetration test (CPT) parameters, such as that outlined in the Dutch national standard NEN 9997-1. A recent update to this standard included revised reduction factors for the pile base resistance. However, it is believed that this update is overly conservative in certain design situations, leading to increasing cost, environmental impact and difficulty of installation. As a result, a national research project was initiated to enhance the understanding of pile-soil interaction effects and their influence on pile design methods. As part of this project, a series of large-scale field tests on fully instrumented piles in dense sand has been executed and are being analysed with a view to refining the national standards and contribute to the existing knowledgebase on piles worldwide. This paper shall provide an overview of two pile test sites that have been developed as part of the programme, along with the design of the testing programme and an overview of the results.