Rapid Load Testing on Piles Interpretation Guidelines

A Rapid Load Test (RLT), developed to determine the initial stiffness and bearing capacity, is an economical and practical alternative to a Static Load Test (SLT). The broad application of RLT, however, was hampered by uncertainty about the interpretation of the test results. This book offers clear guidance on the available analysis techniques and their reliability. The guidelines were related to an international standardthat is drawn up by CEN and can be used in two ways: Straightforward interpretation of test results, chapters 1-3 Interpretation with additional background information about the possibilities and limitations, chapters 4-8 The guidelines were drawn up by the Dutch CUR-committee on rapid load testing on piles. Chapters 1 and 2 deal with the practical execution of the test and the presentation of the results. Chapter 3 gives a general overview of existing interpretation methods and refers to step-by-step descriptions of the two advised interpretation methods. The aspects that are important for the interpretation are discussed in chapter 4, also showing that the inertia of the pile should be taken into account. In clay soil the rate effect (the dependency of strength and stiffness on loading rate) is also of importance, whereas in sand and silt the generation of pore water pressures during an RLT plays a role. The velocity of the RLT is such that the reaction of sand and silt might be considered as partially drained. These guidelines indicate how these effects can be compensated to obtain the static resistance in the final results. Chapter 5 presents two interpretation methods (a method for piles in sand, gravel, silt and piles on rock and a method for piles in clay). For practical use, the methods are described in a step-by-step scheme in an appendix.

PrefaceSummary 1 Introduction and scope of the guidelines 2 Test execution and test results 3 General overview of interpretation methods 3.1 Introduction 3.2 Relevant aspects for the interpretation3.2.1 Inertia effects3.2.2 Rate effects3.3 Description of interpretation methods3.3.1 General3.3.2 Choice of method3.3.3 Short description of the Unloading Point Method3.3.4 Short description of the Sheffield method3.3.5 Methods with more degrees of freedom3.4 Safety approach 4 Theoretical aspects4.1 Introduction4.2 The inverse problem4.3 Dynamic effects4.3.1 Inertial effects for closed piles4.3.2 Inertial effects for open ended pipe piles4.3.3 Damping effects4.4 Rate effects4.4.1 General meaning of rate effect4.4.2 Measuring and modelling the rate effect4.4.3 Constitutive rate effect in dry sand4.4.4 Rate effect in clay4.4.5 Pore water pressures in saturated sand4.5 Combined effects 5 Interpretation methods5.1 Introduction5.2 Unloading point method5.2.1 Definition of the method5.2.2 Measurement / estimation of required parameters5.2.3 Example of the application5.3 Method developed at Sheffield5.3.1 Definition of the method5.3.2 Measurement or estimation of required parameters 6 Safety approach6.1 Method6.2 Partial factors 7 Special aspects7.1 Open-ended piles7.2 Influence of pile installation7.3 Layered soils7.4 Other aspects 8 Symbols and definitions8.1 Symbols8.2 Definitions

Paul Hölscher is a specialist in the application of soil dynamics to practical problems in urban engineering. He obtained his doctorate from Delft University of Technology on the dynamic behaviour of dry and saturated soil. In his 25-year career he worked at Deltares on both fundamental research as well as practical problems for geotechnical engineers. Henk Brassinga is senior consultant of the engineering division of the city of Rotterdam. He has been involved in many large projects in Rotterdam Harbour. Mike Brown is currently a lecturer at the University of Dundee. He obtained his doctorate from the University of Sheffield on the rapid pile testing for piles in clay. Peter Middendorp is director of Allnamics. He contributed to the development of pile driving analysis and the Statnamic test method. He created the basics of unloading point method and has been involved in many large rapid pile tests. Maarten Profittlich is a consultant at Fugro. He is involved in design and testing of foundation piles worldwide. Fugro owns one of the biggest Statnamic devices world wide. Frits van Tol is a professor of Foundation Engineering at Delft University of Technology and expertise manager at Deltares.