Abstract:

In this research, a finite difference method with a relaxation technique were used in a computer program which was prepared to show the influence of changing the status of sheet piles or cutoffs on the uplift pressure under a hydraulic structures.The downstream sheet pile was used inclined to the downstream side with angle of 45°, the beginning of this pile is located before the end of the structure floor with a distance equal to the depth of this pile when it is in a vertical status. With the previous situation of the downstream pile, an upstream and a middle inclined piles were used. The angle of inclination of these two piles are (14°,26°and 45°) to the ward of upstream or downstream of the structures. By comparing all cases with the standard case, the results demonstrated that the new status of downstream pile and the upstream pile inclined with angle of 14° to the downstream side gives a greater decreasing ratio of uplift pressure under the structure floor. The decreasing ratio of the above case is equal to (21.02%). When a middle pile was used in the structure, the best case, is a structure contain an inclined upstream and middle piles with angle of 14° to the downstream side and the downstream pile in the new status. This case gives a total decreasing ratio of uplift pressure equal to (22.46%).

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