Structural performance of profile-wall plastic pipes under relatively shallow soil cover and subjected to large surface load
A total of eleven profile-wall plastic pipe products were instrumented, installed, and tested at the OU-CGER load frame site, which varied from 18 inch diameter PVC pipe to 48 inch diameter HDPE pipe. Each pipe was instrumented with electric resistance strain gages and buried in granular backfill under shallow cover at the load frame facility. Structural performance of the pipes was monitored through strain gages, pressure cells, and a rotational LVDT (linear variable differential transformer) system under application of each load increment. A comprehensive literature review identified a variety of analytical and laboratory test procedures applicable to the buried pipe problem. The analytical methods included the modified Iowa formula, deflection formula by Meyerhof, elastic solutions by Burns and Richard, elastic solutions by Hoeg, finite element method, beam on elastic foundation analysis, ring compression theory, and critical wall buckling formulas. The laboratory methods included parallel-plate load test, one-dimensional compression test, CBR penetration test, and centrifuge modeling. However, most of these were more suitable for analysis of pipes buried deeply. Selected methods were evaluated in light of the latest test results on the plastic pipes under shallow cover. Both modified Iowa formula and deflection formula of Meyerhof predicted field pipe deflections very well when E' values were obtained from the CBR penetration test. Overall quality of the results from the elastic solutions also became improved when E value was based on the data from the CBR penetration test. During the course of this study, interaction was noticed between the rib/corrugation spacing and grain sizes in the backfill soil. The angle for lateral soil pressure distribution was measured to be less than 100 degrees. This finding led to a development of generalized form of the modified Iowa formula.
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:profile wall plastic pipes cbr penetration test linear variable differential transformer finite element method elastic foundation analysis
Date of Publication:01/01/1996