design procedure for rigid airport pavements

304 Pages·2009·7.78 MB·English

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ADA 069 548
1IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIlIII
Report No. FAA·RD·77·81
WES TR-GL-79-4
DEVELOPMENT OF A STRUCTURAL 'DESIGN PROCEDURE
FOR RIGID AIRPORT PAVEMENTS
Frazier Parker, Jr., Walter R. Barker,
Robert C. Gunkel, and Eugene C. Odom
U. S. Army Engineer Waterways Experiment Station
Geotechnical Laboratory
P. O. Box 631, Vicksburg, Miss. 39180
APRIL 1979
FINAL REPORT
Document is available to the public through the
National Technical Information Service,
Springfield, Va. 22161
Prepared for
DEPARTMENT OF DEfENSE U.S. DEPARTMENT OF TRANSPORTATION
DEPARTMENT OF THE ARMY FEDERAL AVIATION ADMINISTRATION
Office, Chief of Engineers Systems Research & Development Service
Washinlton D. C. 20314 Washington, D. C. 20591
~-- - - - -
U_S. O~~:~~~~tCo~~~~~erce~
Natiof1al Technical Inrormation Service
Springfield, Virginia 22161
NOTICES
This document is disseminated under the sponsorship of the Departnent
of Transportation in the interest of information exchange. United
~he
States Government assumes no liability for its contents or use thereof.
The United States does not endorse products or manufacturers.
Governmen~
Trade or manufacturers' names appear herein solely because they are con
sidered essential to the object of this report.
c
PREFACE
The study described herein was sponsored by the Federal Aviation
Administration as a part of Inter-Agency Agreement No. DOT-FA78wAI-377 ,
"New Pavement Design Methodology," and by the Office, Chief of Engi
eers, U. S. Army, as a part of Military Construction RDTE Project No.
4A7627l~J9.!t, "Pavements, Soils, and F01111dations, apd !~ilitary Engi
II
neering RDTE Project No. 4Al6l102B52E, "Research in Military Engineering
and Construction."
The study was conducted under the general supervision of Mr. J. P.
Sale, Chief of the Geotechnical Laboratory, U. S. Army Engineer Waterways
Experiment Station (WES). This report was prepared by Drs. Frazier
Parker, Jr., and Halter R. Barker and Messrs. Robert C. Gunkel and
Eugene C. adorn.
Directors of the WES during the study were COL G. H. Hilt, CE,
and COL J. L. Cannon, CEo Technical Director was Mr. F. R. Brown.·
. Preceding page blank
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TABLE OF CONTENTS
Page
INTRODUCTION . . . 1
.
.
BACKGROUND 1
PURPOSE .. 2
SCOPE •. 2
APPROACH 3
..
SELECTION OF RESPONSE MODEL 4
GENERAL. . . • . .. •. 4
COMPARISONS OF AVAILABLE 1-10DELS 4
OF COMPUTATIONAL PROCEDURE 11
SELECTIO~
i-10DIFICATION OF MODEL FOR FINITE SUBGRADE DEPTHS 15
SELECTION OF MATERIAL CHARACTERIZATION PROCEDURES 28
GENERAL . . . . . . . . . • . . . . . . . . 28
EFFECTS OF LOAD REPETITIONS • . . . . . . 32
MODULUS OF ELAS'l'ICITY AND POISSON'S RATIO. 35
SUNHARY .......... . 38
DEVELOPMENT OF PERFORMANCE CRITERIA 41
GENERAL • . . . . . . . . • . 41
FULL-SCALE ACCELERATED TEST . 46
OF MATERIAL PROPERTIES TO TEST PAVEMENTS 48
ASSIGN~-1ENT
LHITTING STRESS CRITERIA . . . . . . . . . . . 53
VERTICAL DEFLECTION CRITERIA . . . . . . . . . • 57
CRITERIA FOR OVERLAY AND REINFORCED SLAB DESIGN 64
ASSEMBLY OF PROCEDURE FOR DESIG::J' • 72
GENERAL . . . . . . . . . 72
...
MATERIAL SAMPLING . . . . 72
MATERIAL CHARACTERIZATION 74
LAYERED SYSTEM DESIGN . 78
COMPARISCN OF CRITERIA . 98
JOINT DESIGN . . . . . . 107
TRANSLATION FROH DESIGN TO CONSTRUCTION 108
CONCLUSIONS AND RECOMMENDATIONS 110
A: DEVELOPMENT OF 1-1ATERIAL
APPE~mIX
CHARACTERIZATION PROCEDURES . . • . . . . . . . . . . A-I
v
APPENDIX B: DESCRIPTION OF TEST PAVEMENTS • • • • • • B-1
APPENDIX C: LABORATORY PROCEDURE FOR DETERMINING THE
FLEXURAL MODULUS OF BOUND BASES • • , • • C-l
APPENDIX D: LABORATORY PROCEDURE FOR DETERMINING THE
RESILIENT MODULUS OF GRANULAR BASE MATERIALS D-l
APPENDIX,E: LABORATORY PROCEDURE FOR DETERMINING THE ..
RESILIENT MODULUS OF SUBGRADE SOILS • • • E-1
APPENDIX F: APPEnDIX F: USER INFORMATION FOR TijE
BISAR COMPUTER PROGRAM F-1
APPENDIX G: REFERENCES G-l
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INTRODUCTION
BACKGROUND
The motivation for developi,ng a new structural design procedure
1-5
for rigid airport pavements is that currently available procedures
have several weaknesses. This does not imply that the existing proce
dures are not nor does it imply that any proposed new procedure
vali~.
will alleviate all of the weaknesses of the existing procedures.
Rather, the proposed procedure will permit consideration of several
design aspects that are ignored or approximated in available procedures.
The procedures described in References 1-5 are similar in approach
with variations only in certain details. Of interest is the common
approach to modeling the pavement and characterizing the supporting
characteristics of the material beneath the portland cement concrete
(PCC) surface layeT. In all five procedures, the pavement is modeled as
a two-layer system, i.e., the PCC surface layer is as a thin
desc~ibed
elastic plate, and the underlying material is described as a dense liquid
6
(Winkler) foundation. ,7 Other important common features of all five
procedures are: (a) the supporting characteristics of underlying mate
rials are quantified by a single constant, referred to as the
~odulus
of soil reaction; and (b) this constant is determined with plate load
B
tests conducted on in situ materials. ,9
The validity of using a two-layer model and a plate load for
t~st
quantifying the supporting characteri st'ics of the underlying material
are questionable for pavements with relatively thin layers of bound
material and for vehicle gears with large, widely spaced wheel loads.
The procedure developed herein utilizes a layered elastic system for
modeling the pavement and should improve the validity of the computed
pavement response parameters (stress, strain, and deflection) for all
layered systems and loads.
The characteri zation of each layer with f'undamental material
properties obtained from laboratory tests, as opposed to field tests on
in situ material, will permit more flexibility for testing the material
1
at a range of field conditions. The use of a layered model and labora
tory tests to determine properties of the pavement layers will permit
trial of a range of types of materials arranged in various layering
schemes in order to determine an optimized design. The use of labora
tory tests rather than field plate load tests should permit more tests
and, therefore, a better representation of the subgrade.
A final reason for developing. a new.. design procedure for rigid
~.
pavements is the belief among some engineers involved in pavement
design, evaluation, and research that there should be a universal sys
tem applicable to design and evaluation of all types of pavements,
rather than separate procedures for rigid, flexible, or
unsurfac~d
pavements. From a philosophical point of view, this goal certainly is
desirable and is pursuing; but from a practical point of view,
wor~h
there are a number of obstacles that will. only be overcome by advances
in the state of the art of pavement technology. However, there are
• , • • I •
many more similarities between the design procedure contained herein
for rigid pavements and the design procedure contained in Reference 10
for flexible airport pavement than there are between currently
~sed
procedures for rigid and flexible airport pavements. Thus, this design
.
. ,", .
procedure represents a step toward achieving the goal of a universal
design procedure.
PURPOSE
The purpose of this study was to develop a new, practical, and
procedure for the structural design of rigid airport
impleme~table
pavements. This report documents the development' of the methodology
contained in procedure and presents the procedure in a stepwise
t~e
manner for implementation.
SCOPE
The study was limited to the .structural design of the pavement
section, i.e., the selection of required thickness of pavement layers
to carry the design traffic (magnitude and number of loads) under field
conditions. The key words, rigid, practical, implementable, and
2
design, are reflected in the selection of an available linear elastic
response model, available procedures and specific conditions for
m~te­
rial characterizations, and simplified alternatives for accounting for
traffic and environmental conditions. Certainly more sophisticated
response models (finite element) and/or more sophisticated material
characterizations (nonlinear, nonelastic, or viscoelastic) are avail
able, but these are more readily applicable to analysis rather than
routine design. Available test data were used to establish performance
criteria and conditions for material characterization.
No innovations are offered in the treatment of joints in the PCC
surface layer, although joints are the critical location in the pave
ment and models are available for providing at least a rudimentary
treatment. It was believed that these models had not been developed to
the point where they could be used in routine design. Jointing is
considered by specifying certain minimum requirements.
No new methods are offered for the design of overlays. Although
the use of the basic methodology for design of new pavements appears
valid for design of overlays, no acceptable procedure was found to
quantify either the load deformation response of in-place pavements or
interface conditions so that the structural condition of the pavement
would be reflected in the required overlay thickness, or conversely
the performance of the overlay.
APPROACH
The basic approach taken in the study is in the fol-
ou~lined
lowing four tasks:
a. Selection of a response model.
b. Selection of material characterization procedures.
c. Development of performance criteria.
d. Assembly of the methodology into a practical, implementable,
design procedure.
3
SELECTION OF RESPONSE MODEL
GENERAL
·11
The layered elastic model was selected for computing pavement
response parameters. By changing from the presently used model
(Westergaard idealization), implications are that the presently used
model is inadequate and that the layered model offers significant
6
improvements. ,7 These implications may not be totally true and may,
in fact, be completely erroneous in certain respects and for certain
conditions. The problem stems from the judgment of adequacy or what
is best. Such judgment is oftentimes subjective, based on opinion
rather than fact, and in many cases, based on only a limited range of
circumstances. Nevertheless, the selection of the layered elastic
response model was based on what was believed to be sound, rational,
and practical considerations.
COMPARISONS OF AVAILABLE MODELS
12
Crawford and Katona have prepared a state-of-the-art report on
the prediction of pavement response. In their discussions, they refer
to three types of idealizations of pavement structures. These are the
Westergaard, layered elastic, and finite element idealizations. To
these primary idealizations should be added several significant muta
tions and combinations of the three primary idealizations.
13
Hudson and Matlock developed a model that essentially follows
the Westergaard idealization but uses a numerical technique for solving
the equations of bending for the thin elastic slab representing the
surface layer. The numerical technique is based on finite difference
approximations of continuous functions, and the corresponding physical
idealization of the elastic slab is similar to the finite element
idealization. This idealization will be referred to as the discrete
14
element idealization. A model developed by Saxena combines the dis
crete element idealization of the elastic slab with an elastic solid
idealization of the underlying material rather than a dense liquid
idealization. The elastic solid idealization (Boussinesq) is a
4