Semester

Fall

Date of Graduation

2011

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mining and Industrial Extension

Committee Chair

Hema J Siriwardane

Committee Co-Chair

Udaya B Halabe

Committee Member

John D Quaranta

Abstract

Buried pipes are used for several applications, including water conveyance, highway drainage, and the transport of sewage. Throughout the years, it has become increasingly popular to use pipes made of thermoplastic materials due to ease of fabrication, resistance to chemical corrosion, light weight, and low cost. The objective of this research was to investigate the deformations of buried double-corrugated high-density polyethylene (HDPE) and solid-wall polyvinylchloride (PVC) pipes surrounded by a consolidating soil medium. The finite element method was used to calculate the pipe deflections throughout a time period of fifty years. Combined influence of creep and soil consolidation was considered in the analyses, and the results from these analyses were then compared to the deformations of pipes only influenced by the creep of the pipe material. Variables of this study included pipe diameter, height of backfill, pipe backfill material, construction methods, trench-widths, and boundary conditions.;Results show that approximately 90% of pipe deformations occurred during the first year of installation for both the creep analyses and the combined creep and consolidation analyses. However, throughout the first year, the pipe influenced by both the creep and consolidation condition deformed at a much slower rate. Pipes influenced only by the creep condition showed a slightly higher deformation than pipes influenced by both creep and consolidation. This may be due to the instantaneous loading of the pipe, when there is no consolidation. When a pipe is surrounded by a consolidating soil medium, the load on the pipe changes as the pore pressure dissipates as a function of time. Results from the analyses of the combined influence of creep and consolidation are not significantly different from those results obtained from the analyses of creep only behavior of buried HDPE and PVC pipes under the self-weight of soil.

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