Single Piles and Pile Groups

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1 Single Piles and Pile Groups Under Lateral Loading 2nd Edition Lymon C. Reese Academic Chair Emeritus Department of Civil Engineering The University of Texas at Austin William Van Impe Full Professor of Civil Engineering Director Laboratory for Soil Mechanics Ghent University, Belgium Professor Catholic University Leuven, Belgium Taylor & Francis Group Boca Raton London NewYork Leiden CRC Press is an imprint of the Taylor & Francis Group, an informa business A BALKEMA BOOK

2 Contents Preface List of Symbols xv xvii 1 Techniques for design Introduction Occurrence of laterally loaded piles Nature of the soil response Response of a pile to kinds of loading Introduction Static loading Cyclic loading Sustained loading Dynamic loading Models for use in analyses of a single pile Elastic pile and elastic soil Elastic pile and finite elements for soil Rigid pile and plastic soil Characteristic load method Nonlinear pile and p-y model for soil Models for groups of piles under lateral loading Status of current state-of-the-art 20 Homework problems for chapter Derivation of equations and methods of solution Introduction Derivation of the differential equation Solution of reduced form of differential equation Solution of the differential equation by difference equations Solution for = EPy kpyx Dimensional analysis Equations for = Epy kpyx Example solution Discussion Validity of the mechanics 51 Homework problems for chapter 2 52

3 viii Contents 3 Models for response of soil and weak rock Introduction Mechanics concerning response of soil to lateral loading Stress-deformation of soil Proposed model for decay of s Variation of stiffness of soil {Es and Gs) with depth Initial stiffness and ultimate resistance of p-y curves from soil properties Subgrade modulus related to piles under lateral loading Theoretical solution by Skempton for subgrade modulus and for p-y curves for saturated clays Practical use of Skempton's equations and values of subgrade modulus in analyzing a pile under lateral loading Application of the Finite Element Method (FEM) to obtaining p-y curves for static loading Influence of diameter on p-y curves Clay Sand Influence of cyclic loading Clay Sand Experimental methods of obtaining p-y curves Soil response from direct measurement Soil response from experimental moment curves Nondimensional methods for obtaining soil response Early recommendations for computing p-y curves Terzaghi McClelland & Focht for clay (1958) p-y curves for clays Selection of stiffness of clay Response of soft clay in the presence of free water Response of stiff clay in the presence of free water Response of stiff clay with no free water p-y curves for sands above and below the water table Detailed procedure Recommended soil tests Example curves p-y curves for layered soils Method of Georgiadis Example p-y curves p-y curves for soil with both cohesion and a friction angle Background Recommendations for computing p-y curves Discussion Other recommendations for computing p-y curves Clay Sand 105

4 Contents ix 3.12 Modifications to p-y curves for sloping ground Introduction Equations for ultimate resistance in clay Equations for ultimate resistance in sand Effect of batter Shearing force at bottom of pile p-y curves for weak rock Introduction Field tests Interim recommendations for computing p-y curves for weak rock Comments on equations for predicting p-y curves for rock Selection of p-y curves Introduction Factors to be considered Specific suggestions 115 Homework problems for chapter Structural characteristics of piles Introduction Computation of an equivalent diameter of a pile with a noncircular cross section Mechanics for computation of Muit and Eplp as a function of bending moment and axial load Stress-strain curves for normal-weight concrete and structural steel Implementation of the method for a steel h-section Implementation of the method for a steel pipe Implementation of the method for a reinforced-concrete section Example computations for a square shape Example computations for a circular shape Approximation of moment of inertia for a reinforced-concrete section 133 Homework problems for chapter Analysis of groups of piles subjected to inclined and eccentric loading Introduction Approach to analysis of groups of piles Review of theories for the response of groups of piles to inclined and eccentric loads Rational equations for the response of a group of piles under generalized loading Introduction Equations for a two-dimensional group of piles Laterally loaded piles Movement of pile head due to applied loading Effect of batter 147

5 X Contents 5.6 Axially loaded piles Introduction Relevant parameters concerning deformation of soil Influence of method of installation on soil characteristics Methods of formulating axial-stiffness curves Calculation methods for load-settlement behaviour on the basis of in-situ soil tests Differential equation for solution of finite-difference equation for axially loaded piles Finite difference equation Load-transfer curves Closely-spaced piles under lateral loading Modification of load-transfer curves for closely spaced piles Concept of interaction under lateral loading Proposals for solving for influence coefficients for closely-spaced piles under lateral loading Description and analysis of experiments with closely-spaced piles installed in-line and side-by-side Prediction equations for closely-spaced piles installed in-line and side-by-side Use of modified prediction equations in developing p-y curves for analyzing results of experiments with full-scale groups of piles Discussion of the method of predicting the interaction of closely-spaced piles under lateral loading Proposals for solving for influence coefficients for closely-spaced piles under axial loading Modification of load-transfer curves for closely spaced piles Concept of interaction under axial loading Review of relevant literature Interim recommendations for computing the efficiency of groups of piles under axial load Analysis of an experiment with batter piles Description of the testing arrangement Properties of the sand Properties of the pipe piles Pile group Experimental curve of axial load versus settlement for single pile Results from experiment and from analysis Comments on analytical method 202 Homework problems for chapter Analysis of single piles and groups of piles subjected to active and passive loading Nature of lateral loading Active loading 205

6 Contents xi Wind loading Wave loading Current loading Scour Ice loading Ship impact Loads from miscellaneous sources Single piles or groups of piles subjected to active loading Overhead sign Breasting dolphin Pile for anchoring a ship in soft soil Offshore platform Passive loading Earth pressures Moving soil Thrusts from dead loading of structures Single piles or groups of piles subjected to passive loading Pile-supported retaining wall Anchored bulkhead Pile-supported mat at the Pyramid Building Piles for stabilizing a slope Piles in a settling fill in a sloping valley 272 Homework problems for chapter Case studies Introduction Piles installed into cohesive soils with no free water Bagnolet Houston Brent Cross Japan Piles installed into cohesive soils with free water above ground surface Lake Austin Sabine Manor Piles installed in cohesionless soils Mustang Island Garston Arkansas river Roosevelt bridge Piles installed into layered soils Talisheek AlcacerdoSol Florida Apapa Salt Lake International Airport 315

7 xii Contents 7.6 Piles installed in c-0 soil Kuwait Los Angeles Piles installed in weak rock Islamorada San Francisco Analysis of results of case studies Comments on case studies 328 Homework problems for chapter Testing of full-sized piles Introduction Scope of presentation Method of analysis Classification of tests Features unique to testing of piles under lateral loading Designing the test program Planning for the testing Selection of test pile and test site Subsurface investigation Installation of test pile Testing techniques Loading arrangements and instrumentation at the pile head Loading arrangements Instrumentation Testing for design of production piles Introduction Interpretation of data Example Computation Example of testing a research pile for p-y curves Introduction Preparation of test piles Test setup and loading equipment Instrumentation Calibration of test piles Soil borings and laboratory tests Installation of test piles Test procedures and details of loading Penetrometer tests Ground settlement due to pile driving Ground settlement due to lateral loading Recalibration of test piles Graphical presentation of curves showing bending moment Interpretation of bending moment curves to obtain p-y curves Summary 379 Homework problems for chapter 8 379

8 Contents xiii 9 Implementation of factors of safety Introduction Limit states Consequences of a failure Philosophy concerning safety coefficient Influence of nature of structure Special problems in characterizing soil Introduction Characteristic values of soil parameters Level of quality control Two general approaches to selection of factor of safety Global approach to selection of a factor of safety Introductory comments Recommendations of the American Petroleum Institute (API) Method of partial factors (psf) Preliminary Considerations Suggested values for partial factors for design of laterally loaded piles Example computations Method of load and resistance factors (LRFD) Introduction Loads addressed by the LRFD specifications Resistances addressed by the LRFD specifications Design of piles by use of LRFD specifications Concluding comment 395 Homework problems for chapter Suggestions for design Introduction Range of factors to be considered in design Validation of results from computations for single pile Introduction Solution of example problems Check of echo print of input data Investigation of length of word employed in internal computations Selection of tolerance and length of increment Check of soil resistance Check of mechanics Use of nondimensional curves Validation of results from computations for pile group Additional steps in design Risk management Peer review Technical contributions The design team 402

9 xiv Contents APPENDICES A Broms method for analysis of single piles under lateral loading 403 B Nondimensional coefficients for piles with finite length, no axial load, constant Ep/Ip, and constant Epy 419 C Difference equations for step-tapered beams on foundations having variable stiffness 429 D Computer Program COM E F Non-dimensional curves for piles under lateral loading for case where Epy== Ik-pyOCt 451 Tables of values of efficiency measured in tests of groups of piles under lateral loading 461 G Horizontal stresses in soil near shaft during installation of a pile 465 H Use of data from testing uninstrumented piles under lateral loading to obtain soil response 471 I Eurocode principles related to geotechnical design 477 J Discussion of factor of safety related to piles under axial load 481 REFERENCES 485 AUTHOR INDEX 501 SUBJECT INDEX 505

Foundation Engineering

Foundation Engineering P.C. Varghese Foundation Engineering P.C. VARGHESE Honorary Professor, Anna University, Madras Formerly, Professor and Head, Department of Civil Engineering Indian Institute of Technology