Local scour downstream of sluice gates in erosive beds is one of the main concerns of hydraulic engineers because it can cause considerable damage to structures.Many researchers have conducted various studies to predi...Local scour downstream of sluice gates in erosive beds is one of the main concerns of hydraulic engineers because it can cause considerable damage to structures.Many researchers have conducted various studies to predict the maximum depth and length of scour holes and to develop new methods to control this phenomenon.In the methods that have recently been examined,embedded buried plates are used to control the scour in the erosive beds.In this study,using a physical model,the effect of buried plates in erosive beds on the depth of scour downstream of a hydraulic jump was studied.Several experiments were performed in which plates were buried at 50° and 90° angles at different distances from the apron in open channels with horizontal and reverse bed slopes.The results of experiments in which the scour profiles were drawn in dimensionless forms show that the angle and position of the plates are important to controlling and reducing scour depth.In fact,by reducing the angle of buried plates,the maximum depth of scour is also reduced.Also,comparison of the results of a single buried plate and double buried plates shows that using two buried plates at the distances of 30 and 45 cm from the non-erodible bed is more effective in reducing the scour depth.The best distances of the buried plates with angles of 90° and 50° from the non-erodible bed are 45 cm and 30 cm,respectively,in the condition with a single buried plate.展开更多
We discussed the unsteady flow of an incompressible viscous fluid in a rotating parallel plate channel bounded on one side by a porous bed under the influence of a uniform transverse magnetic field taking hall current...We discussed the unsteady flow of an incompressible viscous fluid in a rotating parallel plate channel bounded on one side by a porous bed under the influence of a uniform transverse magnetic field taking hall current into account. The perturbations are created by a constant pressure gradient along the plates in addition to the non-torsional oscillations of the upper plate. The flow in the clean fluid region is governed by Navier-Stoke’s equations while in the porous bed the equations are based on Darcy-Lapwood model. The exact solutions of velocity in the clean fluid and the porous medium consist of steady state and transient state. The time required for the transient state to decay is evaluated in detail and ultimate quasi-steady state solution has been derived analytically and also its behaviour is computationally discussed with reference to different flow parameters. The shear stresses on the boundaries and the mass flux are also obtained analytically and their behaviour is computationally discussed.展开更多
To control land surface subsidence caused the underground mineral exploitation and the catastrophic phenomena such as serious damage of buildings, waterbodies, cultivated lands, railways, bridges caused by land subsid...To control land surface subsidence caused the underground mineral exploitation and the catastrophic phenomena such as serious damage of buildings, waterbodies, cultivated lands, railways, bridges caused by land subsidence, bed separation grouting technology of overburden is put forward. To provide theoretical support for the technology, the characteristics and the mechanics mechanism of mining overburden from layer-split to formation of bed separation are studied. On the basis of elastic sheet board theory, calculation formula of rock sheet deflection is presented, and the mechanics criteria of the separation formation and the calculation formula of bed separation volume are set up. Finally, the applications and technics of bed separation grout technology of mining overburden to control land subsidence in china are introduced.展开更多
文摘Local scour downstream of sluice gates in erosive beds is one of the main concerns of hydraulic engineers because it can cause considerable damage to structures.Many researchers have conducted various studies to predict the maximum depth and length of scour holes and to develop new methods to control this phenomenon.In the methods that have recently been examined,embedded buried plates are used to control the scour in the erosive beds.In this study,using a physical model,the effect of buried plates in erosive beds on the depth of scour downstream of a hydraulic jump was studied.Several experiments were performed in which plates were buried at 50° and 90° angles at different distances from the apron in open channels with horizontal and reverse bed slopes.The results of experiments in which the scour profiles were drawn in dimensionless forms show that the angle and position of the plates are important to controlling and reducing scour depth.In fact,by reducing the angle of buried plates,the maximum depth of scour is also reduced.Also,comparison of the results of a single buried plate and double buried plates shows that using two buried plates at the distances of 30 and 45 cm from the non-erodible bed is more effective in reducing the scour depth.The best distances of the buried plates with angles of 90° and 50° from the non-erodible bed are 45 cm and 30 cm,respectively,in the condition with a single buried plate.
文摘We discussed the unsteady flow of an incompressible viscous fluid in a rotating parallel plate channel bounded on one side by a porous bed under the influence of a uniform transverse magnetic field taking hall current into account. The perturbations are created by a constant pressure gradient along the plates in addition to the non-torsional oscillations of the upper plate. The flow in the clean fluid region is governed by Navier-Stoke’s equations while in the porous bed the equations are based on Darcy-Lapwood model. The exact solutions of velocity in the clean fluid and the porous medium consist of steady state and transient state. The time required for the transient state to decay is evaluated in detail and ultimate quasi-steady state solution has been derived analytically and also its behaviour is computationally discussed with reference to different flow parameters. The shear stresses on the boundaries and the mass flux are also obtained analytically and their behaviour is computationally discussed.
基金Foundation item:Key Project of Natural Seien6e Foundation of China(No:50434020 and NO:50274044)Key Project of Science Foundation of Shandong Province(No:Z20031:02)
文摘To control land surface subsidence caused the underground mineral exploitation and the catastrophic phenomena such as serious damage of buildings, waterbodies, cultivated lands, railways, bridges caused by land subsidence, bed separation grouting technology of overburden is put forward. To provide theoretical support for the technology, the characteristics and the mechanics mechanism of mining overburden from layer-split to formation of bed separation are studied. On the basis of elastic sheet board theory, calculation formula of rock sheet deflection is presented, and the mechanics criteria of the separation formation and the calculation formula of bed separation volume are set up. Finally, the applications and technics of bed separation grout technology of mining overburden to control land subsidence in china are introduced.
