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Critical Vertical Deflection of Buried HDPE Pipes Critical Vertical Deflection of Buried HDPE Pipes A dissertation presented to the faculty of the Russ College of Engineering and Technology of Ohio University In partial fulfillment of the requirements for the degree Doctor of Philosophy Xiao Han April 2017 © 2017 Xiao Han. All Rights Reserved 2 This dissertation titled Critical Vertical Deflection of Buried HDPE Pipes by XIAO HAN has been approved for the Department of Civil Engineering and the Russ College of Engineering and Technology by Teruhisa Masada Professor of Civil Engineering Dennis Irwin Dean, Russ College of Engineering and Technology 3 ABSTRACT HAN, XIAO, Ph.D., April 2017, Civil Engineering Critical Vertical Deflection of Buried HDPE Pipes Director of Dissertation: Teruhisa Masada Profile-wall high-density polyethylene (HDPE) pipes are used at increasing rates to convey surface drainage under roadways. This is because these products are cost effective, easy to handle and resistant to environmental elements. The HDPE pipes are derived from a thermoplastic material and much more flexible compared to the conventional pipes made of concrete and metals. Because of this inherent flexibility and other concerns that exist with thermoplastic materials, many highway agencies in the U.S. specify a limit on the HDPE pipe’s vertical deflection. For example, the Ohio Department of Transportation (ODOT) currently imposes a threshold vertical deflection of 7.5% on all HDPE drainage pipes installed in the ground. Many other state DOTs have similar vertical deflection limits for HDPE pipes. The origin of this vertical deflection limit is not well understood in the engineering community. This study aims at locating the foundation of the threshold vertical deflection enforced by the highway agencies. In the study, different analytical methods and computer simulation models are applied to establish general guidelines concerning the critical vertical deflection for the profile-wall HDPE pipes. The analytical methods employed embrace theories of curved beams, elasticity, and viscoelasticity. In the finite element-based computer simulations, several different diameter sizes of the HDPE pipes are installed in varied installation modes and backfill materials to reflect the AASHTO Construction Specifications. The main outcome of the study makes a clear and reasonable statement about the critical vertical deflection for the commonly used thermoplastic drainage pipes. 4 ACKNOWLEDGMENTS I would like to show my sincere appreciation to my advisor, Dr. Teruhisa Masada, for guiding and assisting me throughout my Ph.D.’s program. I would also like to appreciate Dr. Shad M. Sargand, Dr. Kenneth K. Walsh, and Dr. Greg S. Springer for their invaluable supports and advices to the accomplishment of this dissertation. Finally, I would like acknowledge and appreciate my parents who supported me in many ways during the years I strived for the Ph.D.’s degree. 5 TABLE OF CONTENTS Page Abstract ............................................................................................................................... 3 Acknowledgments............................................................................................................... 4 List of Tables ....................................................................................................................... 8 List of Figures ................................................................................................................... 11 Chapter 1 : Introduction .................................................................................................... 19 1.1 Background ........................................................................................................ 19 1.2 Objective and Tasks ............................................................................................ 20 1.3 Outlines .............................................................................................................. 21 Chapter 2 : Literature Review ........................................................................................... 23 2.1 Origin of Critical Vertical Deflection ................................................................. 23 2.2 Previous Field Tests ............................................................................................ 24 2.3 AASHTO Construction Specifications .............................................................. 36 2.4 Origin of Strain Limit ......................................................................................... 37 Chapter 3 : Methodology .................................................................................................. 39 3.1 Pipe Specifications ............................................................................................. 40 3.2 AASHTO Calculations ....................................................................................... 42 3.2.1 General Description ........................................................................................ 42 3.2.2 Parameters in AASHTO Calculations ............................................................ 43 3.2.3 Procedure of AASHTO Calculations .............................................................. 46 3.3 Theoretical Method ............................................................................................ 54 3.3.1 Spangler Method............................................................................................. 55 3.3.2 Masada Method .............................................................................................. 57 3.3.3 Burns and Richard Method ............................................................................. 58 3.3.4 Hoeg Method .................................................................................................. 62 3.4 CANDE Simulations .......................................................................................... 63 3.4.1 General Descriptions ...................................................................................... 63 3.4.2 Definitions in CANDE Simulations ............................................................... 64 6 Chapter 4 : Results of AASHTO and Other Engineering Methods .................................. 69 4.1 AASHTO Calculation Results ........................................................................... 69 4.1.1 Performances of Pipes under Dead Load Only .............................................. 70 4.1.2 Performances of Pipes under Dead and Live Loads ....................................... 80 4.1.3 Evaluation of AASHTO Calculation Results ................................................. 86 4.1.4 Critical Parameters Determined by AASHTO Calculations ........................... 88 4.2 Theoretical Method Results ............................................................................... 90 4.2.1 Performances of Pipes During Short-Term Service Condition ...................... 92 4.2.2 Performances of Pipes During Long-Term Service Condition ....................... 99 4.2.3 Evaluation of Theoretical Method Results ................................................... 107 4.2.4 Critical Parameters Determined by Theoretical Methods ............................ 109 4.3 CANDE Simulation Results .............................................................................. 111 4.3.1 Performances of Pipes Installed in the Embankment Mode ......................... 112 4.3.2 Performances of Pipes Installed in the Trench Mode ................................... 119 4.3.3 Evaluation of CANDE Simulation Results .................................................. 124 4.3.4 The Critical Coefficients Determined by the CANDE Simulations ............. 127 Chapter 5 : Viscoelastic Analysis .................................................................................... 136 5.1 Background ...................................................................................................... 136 5.2 Methodology .................................................................................................... 139 5.2.1 The Chua and Lytton Method ....................................................................... 140 5.2.2 Abaqus Simulations ...................................................................................... 142 5.2.3 Values of Viscoelastic Coefficients .............................................................. 145 5.3 Results of Viscoelastic Analysis ....................................................................... 150 5.4 Evaluation of Viscoelastic Analysis Results .................................................... 158 5.5 The Critical Coefficients of the Viscoelastic Analysis ..................................... 159 Chapter 6 : Summary and Conclusion ............................................................................ 162 6.1 Summary .......................................................................................................... 162 6.2 Conclusions ...................................................................................................... 163 6.2.1 Task 1: Literature Review ............................................................................. 163 6.2.2 Task 2: Mathematically Calculation ............................................................. 165 7 6.2.3 Task 3: Computer Simulations ..................................................................... 167 6.2.4 Objective 1: Origin of the 7.5% Critical Vertical Deflection ....................... 168 6.2.5 Objective 2: The
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