Application and performance of Culvert design by using HY8 Model: Case Study Al-Musayab canal, Iraq

Abstract

Box culverts represent one of the most important water conveyance structures. Their hydraulic design requires hydrological information, including available discharges and water levels at the upstream and downstream ends of the structure. The hydraulic performance represented by the box culvert design dimensions was examined using HY-8 software, a versatile tool from the U.S. Federal Highway Administration for analyzing various culvert shapes and configurations. This study investigated the hydraulic design of a culvert by using HY-8 software to design and analyze the box culvert while accounting for the hydraulic behavior of the Al Musayab project surrounding area, Babil City, Iraq. HY-8 can model box culverts in a horizontal path to approximate the behavior of hydraulic structures, according to the available discharges, upstream and downstream water levels of the structure, several box culvert simulations that includes (2x2) m, (2.5x2.5) m, (3x3) m, and (4x4) m were tested to select the optimal box design. The design discharge of 35 m³/s for the culvert's incapacity to carry the design flow, the design considered a 4×4 m box shape, the headwater elevation is 31.9 m, which is below the roadway elevation of 33 m. The results of this study provided an evaluation and selection of the best dimensions for the box culvert according to the available discharges. Furthermore, the results shows how to improve the shortage by using an inflatable weir at the exit of the structure so as to increase the water levels along the structure.