Characterization of Model Uncertainty in the Static Pile Design Formula

Level 1 reliability methods have been internationally accepted as the basis for development of the new generation of geotechnical design codes. A key requirement of this design approach is the identification and quantification of uncertainties associated with the geotechnical design under consideration. This paper presents four load test databases from South Africa for driven piles in noncohesive soils (29 tests), bored piles in noncohesive soils (33 tests), driven piles in cohesive soils (59 tests), and bored piles in cohesive soils (53 tests). The capacity model factor is defined as the ratio of the interpreted capacity (Chin-Davisson approach) and the predicted capacity (static pile design formula). The uncertainty in the capacity model factor is modeled as a lognormal random variable. The model factor statistics reported in this study are required for reliability-based ultimate limit state design. The uncertainty in the load-settlement behavior is characterized by fitting measured load-settlement data to a hyperbolic equation and then normalizing the hyperbolic curve with the interpreted capacity. The resulting exercise reduces uncertainties in a set of nonlinear continuous curves to uncertainties in two hyperbolic curve-fitting parameters. This approach is practical and grounded realistically on the load test database with minimal assumptions. The hyperbolic parameter statistics reported in this study are required for reliability-based serviceability limit state design.

[1]  R. B. Robinson,et al.  Identifying outliers in correlated water quality data , 2005 .

[2]  Jean-Louis Briaud,et al.  MEASURED AND PREDICTED AXIAL RESPONSE OF 98 PILES , 1988 .

[3]  Kok-Kwang Phoon,et al.  On Quantifying Inherent Soil Variability , 1996 .

[4]  J. Christian,et al.  Reliability Applied to Slope Stability Analysis , 1994 .

[5]  李幼升,et al.  Ph , 1989 .

[6]  Mahongo Dithinde,et al.  Characterisation of Model Uncertainty for Reliability-Based Design of Pile Foundations , 2007 .

[7]  Frank M Fuller,et al.  PILE LOAD TESTS INCLUDING QUICK-LOAD TEST METHOD, CONVENTIONAL METHODS, AND INTERPRETATIONS , 1970 .

[8]  A.C.W.M. Vrouwenvelder,et al.  The Joint Committee on Structural Safety (JCSS) , 1991 .

[9]  Gregory B. Baecher.  GEOTECHNICAL ERROR ANALYSIS , 1986 .

[11]  S. Lacasse,et al.  Model uncertainty in pile axial capacity calculations , 1996 .

[12]  Murad Y. Abu-Farsakh,et al.  EVALUATION OF BEARING CAPACITY OF PILES FROM CONE PENETRATION TEST DATA , 1999 .

[13]  Pedro Arduino,et al.  Estimation of Uncertainty in Geotechnical Properties for Performance-Based Earthquake Engineering , 2002 .

[14]  Kok-Kwang Phoon.  Serviceability limit state reliability-based design , 2006 .

[15]  V. G. Berezantzev.  Load bearing capacity and deformation of piled foundations , 1961 .

[16]  J E Jennings,et al.  REVISED GUIDE TO SOIL PROFILING FOR CIVIL ENGINEERING PURPOSES IN SOUTHERN AFRICA , 1973 .

[17]  F. H. Kulhawy,et al.  Probabilistic Hyperbolic Models for Foundation Uplift Movements , 2007 .

[18]  Knut O. Ronold,et al.  Model Uncertainty Representation in Geotechnical Reliability Analyses , 1992 .

[19]  Robert V. Whitman,et al.  Organizing and evaluating uncertainty in geotechnical engineering , 2000 .

[20]  Kok-Kwang Phoon,et al.  Reliability-Based Design of Foundations for Transmission Line Structures , 2006 .

[21]  F. H. Kulhawy,et al.  Reliability-based design of foundations for transmission line structures. Final report , 1995 .

[22]  Myassar M. Tabba,et al.  Mapping and Predicting Soil Properties: Theory , 1981 .

[23]  G. Blight,et al.  Compressibility and strength of weathered andesite lava , 1980 .

[24]  F. H. Kulhawy,et al.  Characterization of Model Uncertainties for Augered Cast-In-Place (ACIP) Piles under Axial Compression , 2006 .

[25]  K. Phoon,et al.  Characterization of Geotechnical Variability , 1999 .

[26]  Fred H. Kulhawy,et al.  Estimation of In-Situ Test Uncertainty , 1996 .