OU - Oklahoma Transportation Resources / Oklahoma Transportation Library

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Browsing OU - Oklahoma Transportation Resources / Oklahoma Transportation Library by Author "Ali, Abdelfatah"

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    Energy dissipation in eighteen-foot broken-back culverts using laboratory models (FHWA-OK-12-05)
    (2012-9) Tyagi, Avdhesh K.; Ali, Abdelfatah; Johnson, Nicholas; Motte, Mariazel Rios; Davis, Taylor; Oklahoma Department of Transportation. Materials and Research Division. Office of Research & Implementation
    This report represents Phase III of broken-back culverts with a drop of 18 feet. The first phase of this research was performed for a drop of 24 feet and the second phase of this research was carried out for a drop of 6 feet. This research investigates the reduction in scour downstream of a broken-back culvert by forming a hydraulic jump inside the culvert. A broken-back culvert is used in areas of high relief and steep topography as it has one or more breaks in profile slope. A broken-back culvert in the laboratory represents a 1 (vertical) to 2 (horizontal) slope after the upstream inlet and then continuing 114 feet at a 1 percent slope in the flat part of the culvert to the downstream outlet. Also, in this project, two other slopes, 0.6 and 0.3 percent, were simulated. The prototypes for these experiments were either a two barrel 10-foot by 10-foot, or a two barrel 10-foot by 20-foot reinforced concrete. The drop between inlet and outlet is selected as 18 feet. Three flow conditions were simulated, consisting of 0.8, 1.0 and 1.2 times the culvert depth. The Froude number (Fr1) of the hydraulic jump created in the flat part of the culvert ranges between 2.5 and 4.12. This Fr1 classifies the jump as an oscillating jump. The jump in experiments began nearly at the toe by placing sills in the flat part. For new culvert construction, the best option to maximize energy dissipation under open channel flow conditions is to use one 5-foot sill located 43.3 feet from the outlet. The maximum length of the culvert can be reduced by 30 feet to 43.3 feet. In pressure flow conditions, The optimal location was determined at a distance of 62 feet from the outlet for 2.5-foot sill and at distance of 45 feet from the outlet of face of the culvert for 3.3-foot sill. The length of the culvert can be reduced by 40 feet to 45 feet. Such a scenario is important where right-of-way problems exist for culvert construction. The sills contain two small orifices at the bottom to allow the culvert to completely drain. The impact of friction blocks was found to be minimal. No friction blocks were used to further dissipate the energy. The change of slope in the Broken-Back culvert does not significantly affect to the efficiency of the hydraulic jump.
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    ENERGY DISSIPATION IN THIRTY-FOOT BROKEN-BACK CULVERTS USING LABORATORY MODELS
    (2014-09) Tyahi, Avdhesh; Ali, Abdelfatah; Hamilton, Matthew; Oklahoma Department of Transportation. Materials and Research Division. Office of Research & Implementation
    This research investigates the reduction in scour downstream of a broken-back culvert by forming a hydraulic jump inside the culvert. A broken-back culvert is used in areas of high relief and steep topography as it has one or more breaks in profile slope. A broken-back culvert in the laboratory represents a 1 (vertical) to 2 (horizontal) slope after the upstream inlet and then continuing 90 feet at a 1 percent slope in the flat part of the culvert to the downstream outlet. The prototypes for these experiments were either a two barrel 10-foot by 10-foot, or a two barrel 10-foot by 20-foot reinforced concrete culvert. The drop between inlet and outlet was selected as 30 feet. Three flow conditions were simulated, consisting of 0.8, 1.0 and 1.2 times the culvert depth. This report represents Phase V of broken-back culverts with a drop of 30 feet. The first phase of this research was performed with a drop of 24 feet, the second phase of this research was carried with for a drop of 6 feet, the third phase of this research, performed was a drop of 18 feet, and the fourth phase of this research was performed with a drop of 12 feet.
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    ENERGY DISSIPATION IN TWELVE-FOOT BROKEN-BACK CULVERTS USING LABORATORY MODELS (FHWA-OK-13-07)
    (2013-9) Tyagi, Avdhesh; Ali, Abdelfatah; Hamilton, Matthew; Johnson, Nicholas; Oklahoma Department of Transportation. Materials and Research Division. Office of Research & Implementation
    This report represents Phase IV of broken-back culverts with a drop of 12 feet. The first phase of this research was performed with a drop of 24 feet, the second phase of this research was carried with for a drop of 6 feet, and the third phase of this research, performed was a drop of 18 feet. This research investigates the reduction in scour downstream of a broken-back culvert by forming a hydraulic jump inside the culvert. A broken-back culvert is used in areas of high relief and steep topography as it has one or more breaks in profile slope. A broken-back culvert in the laboratory represents a 1 (vertical) to 2 (horizontal) slope after the upstream inlet and then continuing 126 feet at a 1 percent slope in the flat part of the culvert to the downstream outlet. The prototypes for these experiments were either a two barrel 10-foot by 10-foot, or a two barrel 10-foot by 20-foot reinforced concrete culvert. The drop between inlet and outlet was selected as 12 feet. Three flow conditions were simulated, consisting of 0.8, 1.0 and 1.2 times the culvert depth. The Froude number (Fr1) of the hydraulic jump created in the flat part of the culvert ranged between 2.21 and 3.32. This Fr1 classifies the jump as an oscillating jump. The jump began nearly at the toe by placing sills in the flat part. For new culvert construction, the best option to maximize energy dissipation under open channel flow conditions is to use one 4.2-foot sill located 58.33 feet from the outlet. The maximum length of the culvert can be reduced from 45 feet to 58 feet. In pressure flow conditions, the optimal location was determined at a distance of 88 feet from the outlet for 2.5-foot sill. The length of the culvert can be reduced by 60 feet to 75 feet. Such a scenario is important where right-of-way problems exist for culvert construction. Also examined was a slotted sill which has a cut in the middle for cleanup purposes. In open channel flow conditions, the best option to maximize energy dissipation is to use one 5-foot slotted sill located 70 feet from the outlet. In the pressure flow conditions, the optimal slotted sill was 3.33-foot at a distance of 88 feet from the outlet. The regular and slotted sills contain two small orifices at the bottom to allow the culvert to completely drain. The impact of friction blocks was found to be minimal. No friction blocks were used to further dissipate the energy. In sedimentation experiments under regular and slotted sills, there was no sedimentation left.