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DissertationDOI

Laboratory load tests of side shear for axially loaded piles

01 Jan 2008-

AbstractSteel H-piles are small displacement deep foundation elements. Typically, Hpiles are driven to/into a hard stratum and the axial capacity of the pile is derived from the end bearing of the pile tip on the hard stratum. However, H-piles can be and are used as friction piles. Presumably, if the side shear capacity of a given H-pile can be increased, the use and applicability of H-piles will also increase. Conventional H-piles have smooth flanges. The objective of the research presented was to evaluate the effect that texturing of pile flanges has on the side shear capacity of an H-pile. The objective was addressed by performing a series of laboratory load tests on full-scale sections of smooth (HP) and textured (HPX) piles to assess differences in load transfer via side shear. Results from the laboratory testing program suggest that HPX-piles have approximately 10 percent greater side shear capacity than conventional HP-piles, on average. Unit side shear and the side shear parameter β for both smooth and textured piles generally increased with increasing effective stress and increasing over consolidation ratio. HPX-piles were found to exhibit slightly greater settlement at failure than HP-piles, although scatter in the settlement data was significant.

Topics: Shear (geology) (53%)

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Public Abstract
First Name:Nathan
Middle Name:Sheil
Last Name:Rose
Adviser's First Name:J. Erik
Adviser's Last Name:Loehr
Co-Adviser's First Name:
Co-Adviser's Last Name:
Graduation Term:FS 2008
Department:Civil Engineering
Degree:MS
Title:Laboratory Load Tests of Side Shear for Axially Loaded Piles
Steel H-piles are small displacement deep foundation elements. Typically, H-piles are driven to/into a
hard stratum and the axial capacity of the pile is derived from the end bearing of the pile tip on the hard
stratum. However, H-piles can be and are used as friction piles. Presumably, if the side shear capacity of
a given H-pile can be increased, the use and applicability of H-piles will also increase. Conventional H-piles
have smooth flanges. The objective of the research presented was to evaluate the effect that texturing of
the pile flanges has on the side shear capacity of an H-pile.
Experimental data was obtained from laboratory axial load tests on eight foot sections of smooth HP-
piles and textured HPX-piles. The experimental apparatus includes a chamber assembly, reaction frame,
bladder system, and instrumentation system. All tests were performed using clean poorly graded sand.
The experimental apparatus was constructed such that the piles were not subjected to any end bearing;
only side shear was measured. The load test procedure was based on of the ASTM D-1143 Quick Load
Test Method. Axial load was applied via a hydraulic jack. Instrumentation included dial gauges for
measuring pile settlement, a load cell for measuring axial load, and a pressure transducer to measure the
bladder pressure. 
The testing program consisted of eight series of load tests; three test series for HP 14x76 piles and five
test series for HPX 14x76 piles. Each test series consisted of multiple load tests performed at vertical
effective stresses ranging from approximately 1300 psf to 4000 psf. Pile settlement, axial load and bladder
pressure were monitored and recorded for each load test. The unit weight of the sand was measured for
each test series. 
The ultimate unit side shear and side shear parameter ï•¢ were back calculated based on the ultimate pile
capacity, pile-soil interface area, and vertical effective stress. The unit side shear was evaluated in terms of
vertical effective stress. The side shear parameter ï•¢ was evaluated in terms of vertical effective stress and
over consolidation ratio. Pile settlement at failure was also evaluated. Statistical analyses were performed
for all evaluations to assess the significance of differences between the HP and HPX piles. The back
calculated side shear parameter ï•¢ values were compared with typical literature values and the ultimate pile
capacities were compared to side by side field load tests of HP and HPX piles.
Results from the laboratory testing program suggest that HPX-piles have approximately 10 percent
greater side shear capacity than conventional HP-piles, on average. Unit side shear and the side shear
parameter ï•¢ for both smooth and textured piles generally increased with increasing effective stress and
increasing over consolidation ratio. HPX-piles were found to exhibit slightly greater settlement at failure
than HP-piles, although scatter in the settlement data was significant. 
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Book
01 Jan 2003
Abstract: Preface. Part I. 1 Introduction - uncertainty and risk in geotechnical engineering. 1.1 Offshore platforms. 1.2 Pit mine slopes. 1.3 Balancing risk and reliability in a geotechnical design. 1.4 Historical development of reliability methods in civil engineering. 1.5 Some terminological and philosophical issues. 1.6 The organization of this book. 1.7 A comment on notation and nomenclature. 2 Uncertainty. 2.1 Randomness, uncertainty, and the world. 2.2 Modeling uncertainties in risk and reliability analysis. 2.3 Probability. 3 Probability. 3.1 Histograms and frequency diagrams. 3.2 Summary statistics. 3.3 Probability theory. 3.4 Random variables. 3.5 Random process models. 3.6 Fitting mathematical pdf models to data. 3.7 Covariance among variables. 4 Inference. 4.1 Frequentist theory. 4.2 Bayesian theory. 4.3 Prior probabilities. 4.4 Inferences from sampling. 4.5 Regression analysis. 4.6 Hypothesis tests. 4.7 Choice among models. 5 Risk, decisions and judgment. 5.1 Risk. 5.2 Optimizing decisions. 5.3 Non-optimizing decisions. 5.4 Engineering judgment. Part II. 6 Site characterization. 6.1 Developments in site characterization. 6.2 Analytical approaches to site characterization. 6.3 Modeling site characterization activities. 6.4 Some pitfalls of intuitive data evaluation. 6.5 Organization of Part II. 7 Classification and mapping. 7.1 Mapping discrete variables. 7.2 Classification. 7.3 Discriminant analysis. 7.4 Mapping. 7.5 Carrying out a discriminant or logistic analysis. 8 Soil variability. 8.1 Soil properties. 8.2 Index tests and classification of soils. 8.3 Consolidation properties. 8.4 Permeability. 8.5 Strength properties. 8.6 Distributional properties. 8.7 Measurement error. 9 Spatial variability within homogeneous deposits. 9.1 Trends and variations about trends. 9.2 Residual variations. 9.3 Estimating autocorrelation and autocovariance. 9.4 Variograms and geostatistics. Appendix: algorithm for maximizing log-likelihood of autocovariance. 10 Random field theory. 10.1 Stationary processes. 10.2 Mathematical properties of autocovariance functions. 10.3 Multivariate (vector) random fields. 10.4 Gaussian random fields. 10.5 Functions of random fields. 11 Spatial sampling. 11.1 Concepts of sampling. 11.2 Common spatial sampling plans. 11.3 Interpolating random fields. 11.4 Sampling for autocorrelation. 12 Search theory. 12.1 Brief history of search theory. 12.2 Logic of a search process. 12.3 Single stage search. 12.4 Grid search. 12.5 Inferring target characteristics. 12.6 Optimal search. 12.7 Sequential search. Part III. 13 Reliability analysis and error propagation. 13.1 Loads, resistances and reliability. 13.2 Results for different distributions of the performance function. 13.3 Steps and approximations in reliability analysis. 13.4 Error propagation - statistical moments of the performance function. 13.5 Solution techniques for practical cases. 13.6 A simple conceptual model of practical significance. 14 First order second moment (FOSM) methods. 14.1 The James Bay dikes. 14.2 Uncertainty in geotechnical parameters. 14.3 FOSM calculations. 14.4 Extrapolations and consequences. 14.5 Conclusions from the James Bay study. 14.6 Final comments. 15 Point estimate methods. 15.1 Mathematical background. 15.2 Rosenblueth's cases and notation. 15.3 Numerical results for simple cases. 15.4 Relation to orthogonal polynomial quadrature. 15.5 Relation with 'Gauss points' in the finite element method. 15.6 Limitations of orthogonal polynomial quadrature. 15.7 Accuracy, or when to use the point-estimate method. 15.8 The problem of the number of computation points. 15.9 Final comments and conclusions. 16 The Hasofer-Lind approach (FORM). 16.1 Justification for improvement - vertical cut in cohesive soil. 16.2 The Hasofer-Lind formulation. 16.3 Linear or non-linear failure criteria and uncorrelated variables. 16.4 Higher order reliability. 16.5 Correlated variables. 16.6 Non-normal variables. 17 Monte Carlo simulation methods. 17.1 Basic considerations. 17.2 Computer programming considerations. 17.3 Simulation of random processes. 17.4 Variance reduction methods. 17.5 Summary. 18 Load and resistance factor design. 18.1 Limit state design and code development. 18.2 Load and resistance factor design. 18.3 Foundation design based on LRFD. 18.4 Concluding remarks. 19 Stochastic finite elements. 19.1 Elementary finite element issues. 19.2 Correlated properties. 19.3 Explicit formulation. 19.4 Monte Carlo study of differential settlement. 19.5 Summary and conclusions. Part IV. 20 Event tree analysis. 20.1 Systems failure. 20.2 Influence diagrams. 20.3 Constructing event trees. 20.4 Branch probabilities. 20.5 Levee example revisited. 21 Expert opinion. 21.1 Expert opinion in geotechnical practice. 21.2 How do people estimate subjective probabilities? 21.3 How well do people estimate subjective probabilities? 21.4 Can people learn to be well-calibrated? 21.5 Protocol for assessing subjective probabilities. 21.6 Conducting a process to elicit quantified judgment. 21.7 Practical suggestions and techniques. 21.8 Summary. 22 System reliability assessment. 22.1 Concepts of system reliability. 22.2 Dependencies among component failures. 22.3 Event tree representations. 22.4 Fault tree representations. 22.5 Simulation approach to system reliability. 22.6 Combined approaches. 22.7 Summary. Appendix A: A primer on probability theory. A.1 Notation and axioms. A.2 Elementary results. A.3 Total probability and Bayes' theorem. A.4 Discrete distributions. A.5 Continuous distributions. A.6 Multiple variables. A.7 Functions of random variables. References. Index.

1,103 citations



Journal ArticleDOI
Abstract: Auger‐cast piles are formed by drilling a continuous flight auger into the ground and, on reaching the required depth, pumping grout or concrete down the hollow stem as the auger is steadily withdrawn. The sides of the hole are supported by the soil‐filled auger, eliminating the need for temporary casing or bentonite slurry. This paper outlines important features of auger‐cast pile installation that influence the structural integrity and geotechnical capacity of completed piles. These include soil decompression, correlation between the rotational and vertical speeds of the auger, and precise coordination of auger extraction and grout supply. The results of 66 loading tests on auger‐cast piles in sand are presented. Shaft resistance is found to be independent of the relative density of the sand, while point resistance can be directly correlated with results of standard penetration and cone penetrometer tests. Empirical design methods for bored piles were found to underestimate the failure loads of auger‐ca...

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Book
29 Jan 2009
Abstract: Review of Soil Mechanics Concepts and Analytical Techniques Used in Foundation Engineering Manjriker Gunaratne In Situ Soil Testing Austin Gray Mullins Spread Footings: Analysis and Design Manjriker Gunaratne Geotechnical Design of Combined Spread Footings Manjriker Gunaratne Structural Design of Foundations Panchy Arumugasaamy Design of Driven Piles and Pile Groups Manjriker Gunaratne Design of Drilled Shafts Austin Gray Mullins Design of Laterally Loaded Piles Manjriker Gunaratne Construction Monitoring and Testing Methods of Driven Piles Manjriker Gunaratne and Austin Gray Mullins Retaining Walls: Analysis and Design Alaa Ashmawy Stability Analysis and Design of Slopes Manjriker Gunaratne Methods of Soft Ground Improvement James D. Hussin Impact of Groundwater on the Design of Earthen Structures Manjriker Gunaratne Index

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