Water Resources Engineering
Farshid Taran; Ghorban Mahtabi
Articles in Press, Accepted Manuscript, Available Online from 02 May 2024
Abstract
One of the main issues threatening hydraulic structures is the uplift pressure caused by the water flow in the porous media under the structures. Cut-off walls installed underneath a hydraulic structure can reduce the uplift pressure, by changing the water flow velocity, and as a result, the possibility ...
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One of the main issues threatening hydraulic structures is the uplift pressure caused by the water flow in the porous media under the structures. Cut-off walls installed underneath a hydraulic structure can reduce the uplift pressure, by changing the water flow velocity, and as a result, the possibility of cracking and fracturing in the body of the structure. In this study, the effect of inclined cut-off walls with different angles of inclination (to the horizontal axis) underneath an irrigation canal (with laboratory dimensions) on the water flow velocity in the porous medium was investigated. The changes in the velocity due to the inclination were obtained using the Hydrus-2D numerical model. The velocity under the canal with no cut-off walls showed slight fluctuations, but increased owing to all the angles of inclination, reaching its maximum at the location of the cut-off walls. The most effective cut-off walls in increasing the velocity were the closest ones to the horizontal axis, i.e., those with angles of 15°, 30° and 165°, while the less effective angles were 90° and 120°, which were closer to the vertical line. The velocity just below the canal bottom increased with the increase in the angle, so that it changed by 18.05% and 209.45% due to the angles 15° and 165°, respectively. In fact, the cut-off walls performed better as they inclined from the earth’s surface to the canal bottom.
Water Resources Engineering
B. Oghati Bakhshayesh; F. Salmasi; S. Haji Azizi
Abstract
Underground water levels and pore water pressure can be increased as a result of heavy rainfall which can lead failure of earthen slopes. Retaining walls are the most well-known structures in order to increase earthen slope stability. In this study, the stability of earthen slopes is numerically simulated ...
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Underground water levels and pore water pressure can be increased as a result of heavy rainfall which can lead failure of earthen slopes. Retaining walls are the most well-known structures in order to increase earthen slope stability. In this study, the stability of earthen slopes is numerically simulated in critical hydrological situations. The simulations included pore pressure behind the retaining walls which lead to instability. Among the investigated parameters were: precipitation intensity, soil type, position and the diameter of drainage passages. Both horizontal and chimney drainages were simulated for the study. For fine-grained soils with intensive precipitation, using a single horizontal drainage passageway could not maintain sufficient stability for the retaining wall. Precipitation could have severe impact on stability in which increase of 5 to 15 mm/h would increase pore pressure from 7.09 kN to 75.39 kN which is so dramatic change. For coarse-grained soils, a retaining wall provides stability with a single horizontal drainage pipe; the horizontal pipe is able to discharge all the excess water behind the retaining wall. A chimney drainage system provided the best results, and the stability of the retaining wall did not endanger, even under the worst circumstances. Linear and non-linear regression relations were produced in dimensionless form which are providing 0.97 for R2 and 0.11 for RMSE values which implys the accurcy of equations. The accuracy of the regression determine their usage in practical applications.
