Evaluation On Minimum And Maximum Cover Thickness For Reinforced Concrete Pipe Culvert Under Embankment In Jimma Town

Abstract

In most highway construction of asphalt and gravel road project, requires an installation of pipe culvert, across and along the side of the road under the surface layer. This research study covered evaluating the minimum and maximum fill embankment height over the top of the pipe and assessment of factors that would affect the strength of pipe culvert like trench width and quality of contact between the pipe and bedding, pipe strength, bedding type, magnitude of lateral pressure, axial thrust. The main objective of the study was to set out the minimum and maximum fill embankment height over the top of the pipe culvert. The procedure followed was accomplishing laboratory tests to understand the property of backfill materials and apply pipe Pac software for further analysis by using data obtained from laboratory results Application of different types of loading on pipe culvert has been considered and laboratory tests like compaction test, sieve analysis, hydrometer, specific gravity, and Atterberg limit test, for design and analysis purpose has been carried out. Sample has gathered from the site and enabled to get existing design data. Stress analysis by using Boussinesq’s theory to get the depth at which stress influence has minimum. From the compaction test results of each site, backfill materials from Seka borrow pit has highest percentage relative compaction but Jiren borrow pit has lowest percentage relative compaction. The minimum and maximum cover thickness decided after evaluation was 1.6m and 0.3m respectively. This research paper concludes the maximum backfill depth for each site were calculated and the values obtained were specific to the site and within the standard specification. It also recommends blending backfill materials that are poor graded, and settlement analysis of foundation under pipe culvert.