Load Capacity of Pipe Piles in Cohesive Ground: Fid-Bau Portal

Load Capacity of Pipe Piles in Cohesive Ground

Diyaljee, Vishnu / Pariti, Murthy

Very often highway departments drive test piles at proposed bridge locations to refusal or to a predetermined set and utilize these records to determine the pile capacity using the Hiley and Engineering News Record pile driving formulae. This test pile driving also provides information on the depth to which the piles can be driven and on problems that may likely be encountered during production piling. The pile capacity obtained from pile driving formulae is generally used by the structural engineer to undertake the preliminary design of the bridge foundations. The use of the pile driving approach to capacity determination often works well when the ground is competent at relatively shallow depths. However, where piles cannot achieve refusal unless driven into stiff or hard ground a geotechnical evaluation of pile capacity becomes more relevant and is often relied upon for pile capacity determination. This paper describes a site where H-pile and closed end pipe piles attained refusal at a depth of 31 metres in hard clay till and where the geotechnical evaluation recommended that the pier piles be terminated at a higher elevation. To demonstrate that the geotechnical recommendations were acceptable, static load testing and Pile Driving Analyzer tests were undertaken. The detailed testing program demonstrated that the driving of piles to refusal was not necessary to achieve the desired pile capacities and that conventional static analysis provided capacities that were sufficiently reliable for design.