Analysis of a rapid load test on an instrumented bored pile in clay

TY - JOUR

T1 - Analysis of a rapid load test on an instrumented bored pile in clay

AU - Brown, M. J.

AU - Hyde, A. F. L.

AU - Anderson, W. F.

N1 - dc.publisher: Institution of Civil Engineers

PY - 2006

Y1 - 2006

N2 - Rapid load testing methods for piled foundations are generally easier and quicker to mobilise than classic static tests, and are less complex to analyse than dynamic load tests. A recently developed rapid load pile testing method known as the Statnamic test is seeing greater use in the UK for the assessment of piles. For foundation design, it is necessary to derive the equivalent static load-settlement curve from the rapid load test data by eliminating inertial and damping effects. Existing methods of test analysis generally provide good correlation with static tests for sands and gravels, but overpredict pile capacities by up to 50% for clays. In order to gain an insight into the behaviour of rapid load pile testing in clays, a full-scale pile instrumented with accelerometers, strain-gauged sister bars and a tip load cell was tested in a glacial lodgement till near Grimsby, UK. The soil around the pile was also instrumented with radially arrayed buried accelerometers. The test pile was subjected to rapid loading tests, the results of which were compared with constant rate of penetration and maintained load static tests on the same pile. Results from the field testing have been analysed using non-linear viscous parameters obtained from laboratory model and element tests to represent rate-dependent clay shear resistance in the post-yield phase of loading. Shaft frictions derived from the strain-gauged reinforcement in the pile have been compared with shear strains and stresses derived from accelerations in the surrounding soil to give an insight into the load transfer mechanisms for a rapidly loaded pile in clay. Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees. http://www.icevirtuallibrary.com/content/journals

AB - Rapid load testing methods for piled foundations are generally easier and quicker to mobilise than classic static tests, and are less complex to analyse than dynamic load tests. A recently developed rapid load pile testing method known as the Statnamic test is seeing greater use in the UK for the assessment of piles. For foundation design, it is necessary to derive the equivalent static load-settlement curve from the rapid load test data by eliminating inertial and damping effects. Existing methods of test analysis generally provide good correlation with static tests for sands and gravels, but overpredict pile capacities by up to 50% for clays. In order to gain an insight into the behaviour of rapid load pile testing in clays, a full-scale pile instrumented with accelerometers, strain-gauged sister bars and a tip load cell was tested in a glacial lodgement till near Grimsby, UK. The soil around the pile was also instrumented with radially arrayed buried accelerometers. The test pile was subjected to rapid loading tests, the results of which were compared with constant rate of penetration and maintained load static tests on the same pile. Results from the field testing have been analysed using non-linear viscous parameters obtained from laboratory model and element tests to represent rate-dependent clay shear resistance in the post-yield phase of loading. Shaft frictions derived from the strain-gauged reinforcement in the pile have been compared with shear strains and stresses derived from accelerations in the surrounding soil to give an insight into the load transfer mechanisms for a rapidly loaded pile in clay. Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees. http://www.icevirtuallibrary.com/content/journals

KW - Piles

KW - Dynamics

KW - Clays

KW - Glacial soils

KW - Field instrumentation

KW - Full-scale tests

KW - Statnamic load testing

KW - Pile testing, static, bi-directional, dynamic, rapid

U2 - 10.1680/geot.2006.56.9.627

DO - 10.1680/geot.2006.56.9.627

M3 - Article

SN - 0016-8505

VL - 56

SP - 627

EP - 638

JO - Géotechnique

JF - Géotechnique

IS - 9

ER -