Field Performance and Analysis of Large-Diameter High-Density Polyethylene Pipe under Deep Soil Fill S. M. Sargand, M.ASCE 1 ; T. Masada, A.M.ASCE 2 ; B. Tarawneh 3 ; and D. Gruver 4 Abstract: This paper presents field performance of 1,524-mm 60-in. diameter, corrugated high-density polyethylene (HDPE) pipes installed at the Ohio University–ORITE deep burial site. The pipes have been subjected to 6.1-m 20-ft. or 12.2-m 40-ft. high embankment fill for about 2 years. Structural performance of each pipe was monitored with various sensors during initial backfilling, during embankment construction, and after embankment construction. The data accumulated in the field indicated that these pipes were performing satisfactorily, showing little signs of structural distress. Examination of the field data revealed some valuable insights into the large-diameter, flexible pipe performance under deep soil cover. In addition, selected analytical methods were evaluated using the field data. An improved approach based on the modified Iowa formula was generally effective in estimating the horizontal deflection. Elastic solutions showed a limited ability in describing the field performance of these large-diameter HDPE pipes. The powerful nature of the finite element computer program CANDE-89 was recognized but not fully demonstrated in numerical simulations of the field installation conditions because of a few shortcomings in CANDE-89 computer analysis. DOI: 10.1061/(ASCE)1090-0241(2005)131:1(39) CE Database subject headings: Flexible pipes; Deflection; Finite element; Performance; Fills; Polyethylene. Introduction Large-diameter thermoplastic pipes have been utilized increas- ingly to convey surface drainage under roadways in place of con- ventional short-span bridges and culverts. This trend is due to some merits (such as light weight, cost efficiency, and chemical resistance) that the thermoplastic pipes offer over the conven- tional pipes. Although there have been numerous papers and re- ports published on the structural behavior of plastic pipes, com- prehensive field performance data are nearly nonexistent for large-diameter flexible pipes under realistic field loading condi- tions over a prolonged period of time. The lack is due to the fact that the large-diameter thermoplastic pipes are relatively new products and that long-term full-scale field tests are costly and labor-intensive. Only two cases of long-term, deep burial test results were reported for thermoplastic pipes prior to the subject field study. Hashash and Selig (1990) published long-term performance data for a 610-mm 24-in. diameter, corrugated high-density polyeth- ylene (HDPE) pipe placed under a 30.5-m 100-ft. high embank- ment in Pennsylvania. The pipe was backfilled with a crushed limestone compacted to 100% of the maximum dry unit deter- mined by the standard Proctor test (AASHTO T-99). They ob- served that the pipe responses stabilized shortly after the end of construction. Under the embankment loading, the vertical diam- eter of the pipe decreased by 4.3% and the horizontal diameter increased by 0.6%. The pipe contracted circumferentially by about 1.6%. The vertical soil pressure measured at the crown was only 23% of the estimated geostatic pressure. Sargand and Masada (2000) monitored field performance of HDPE pipes under an embankment loading at the State Route 7 construction site in Ohio for about 1 year. The pipes had a hon- eycomb (HC) design and a nominal diameter of 1,050 mm 42 in.. The pipes were backfilled with a dumped gravel and subjected to a 15.8-m 52-ft. high soil fill. The horizontal deflec- tion stabilized within 40 days, but a much longer time was nec- essary for the vertical deflection to stabilize. Over time, the ver- tical soil pressure measured at the crown and invert decreased slightly, while the lateral soil pressure measured at the springline increased slightly. They observed that the deflections of the main test pipe stabilized to -10% vertical and 3% horizontal. The ver- tical soil pressure at the crown was typically about 26% of the estimated geostatic pressure. ORITE Deep Burial Study In 1999, the ORITE started a thermoplastic pipe deep burial study for the Ohio Department of Transportation (ODOT) and partici- pating plastic pipe manufacturers. The site is located next to the Ohio University’s airport in Albany, Ohio. Eighteen thermoplastic (12 HDPE and 6 PVC) test pipes were installed and monitored at the site. The nominal diameter ranged from 762 mm 30 in. to 1,524 mm 60 in.. Details of the project can be found in the final report by Sargand et al. (2002). 1 Russ Professor, Dept. of Civil Engineering, Ohio Research Institute for Transp. and Environ., Ohio Univ., Athens, OH 45701. 2 Associate Professor, Civil Engineering, Ohio Research Institute for Transp. and Environ., Ohio Univ., Athens, OH 45701. 3 Graduate Research Associate, Civil Engineering, Ohio Univ., Athens, OH 45701. 4 Hyd. Review Engineer, Office of Structural Engineering, Ohio Dept. of Transportation (ODOT), Columbus, OH 43223. Note. Discussion open until June 1, 2005. Separate discussions must be submitted for individual papers. To extend the closing date by one month, a written request must be filed with the ASCE Managing Editor. The manuscript for this paper was submitted for review and possible publication on July 9, 2002; approved on July 22, 2004. This paper is part of the Journal of Geotechnical and Geoenvironmental Engineering, Vol. 131, No. 1, January 1, 2005. ©ASCE, ISSN 1090-0241/2005/1-39– 51/$25.00. 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