RA Davis MSc, CEng, MI Struct E, JN Mure BSc, CEng, MICE and ML Kightley BSc. This paper was first published in GE’s November 1987 edition.
The high cost of static load testing piles has prompted successive efforts to determine the static load capacity of piles by observing the way in which they respond to driving. The CAPWAPC method of analysis (Case Pile Wave Analysis Program— Continuous Version) addresses this problem and is described in this paper. The method is named after the Case Western Reserve University in the USA and is carried out by Testing and Analysis Ltd. of Derbyshire on equipment made by Pile Dynamics Inc. of Cleveland Ohio.
The analysis of the pile follows a procedure similar to that described by F. Rausche, F. Moses and G.G. Goble (1). This technique (1) has been much improved and now carries out computations interactively or iteratively on a segmental pile model. Data is obtained from an accelerometer and strain gauge bolted to the head of the pile. The results not only include the static pile capacity and load displacement diagrams but also indicate where on the pile the soil resistance is felt. In addition any pile damage can be located.
This is the first of two complementary papers dealing with this subject by the same authors. It shows how wave propagation affects pile driving and gives an explanation of the CAPWAPC program. Typical pile test results are also given. The equations used herein to explain CAPWAPC were taken from an unpublished report by F. Rausche of Pile Dynamics Inc.
The second paper, to be published in the next issue, will deal with case histories and will demonstrate the range and accuracy of the method. It will also cover instrumentation and costs.