A statistical Model to simulate the Geometry of the Tunnel Gates Lips

Abstract

The determination of the down pull force for the tunnel gates requires the estimation of the water pressure coefficient (KB), which is affected by the geometry of the gate lip and the water flow beneath the gate. The prediction of (KB) is depended upon the mean head pressure and the distribution of velocity along the bottom gate surface for each lip geometry. A statistical model is predicted to estimate the bottom water pressure coefficient (KB) of the down pull force for a tunnel gate lip.This model is developed from relevant experimental data obtained from hydraulic model tests conducted in laboratory for nine gate lip geometries with nine gate openings for each gate lip geometry to ensure the correctness of the model results by comparing them these data. The statistical model is verified with (SPSS) software for a good correlation coefficient equal to (0.95). The statistical model is applied to reveal the distribution of the (KB) values on the gate bottom surface along the gate lips with different openings ratios between (0.1-0.9) and is indicated the extensions with round edge of the inclined gates lips. From the distribution of the (KB) values indicate that these values are high and vary smoothly along the gate lip for openings ratio between (0.1-0.5), with complete attachment from the leading edge to the trailing edge of the gate bottom surface. For other gate openings (0.6-0.9), the flow is attached at the leading edge of gate bottom and then decreased toward the trailing edge of gate with smooth variation. While the inclined gate lips with extensions reveal that the values of (KB) are approximately constant and uniform which representing stability of gate along the bottom gate surface for openings ratio between (0.1-0.5), and for other gate openings ratio these values vary smoothly from the leading edge to the trailing edge of the bottom surface of gate. Also, the influence of rounded edge of gate lip with (r/d = 1) on the distribution of pressure head along the bottom surface of gate is investigated, where the values of the (KB) values are dropped and decreased toward the trailing edge of gate.