Numerical Simulation Study On The Effect Of Flow Diversion And Sediment Regulation By Permeable Sheet Piling Spur Dike

With the continuous innovation and development of new concepts,new theories,new technologies,new methods,and new models of river regulation,water and sediment regulation has become a new research direction for river regulation.The study of water and sediment regulation has engineering theory and application value for bank protection,river management and ecological restoration.Permeable spur dams play an important role in river regulation and ecological restoration and protection.As a new type of dam-type permeable bank protection structure,the permeable sheet piling spur dike plays a significant role in the regulation of sediment-laden rivers.This paper based on the theory of water and sediment regulation of other bank protection structures and the theory of the bank protection mechanism of the permeable sheet piling spur dike,the paper arranges the permeable sheet piling spur dike at the place easy to be scoured and silted in silt laden river channel.By using numerical simulation test,studied on the flow diversion and sediment diversion,sediment retention and desilting effects of the permeable spur dike,and the beach-making effect of permeable sheet piling spur dikes are studied.By simulating the effects of permeable sheet piling spur dike on water and sediment separation,retention,desilting and beach-making,to study the effect of water and sediment regulation.The main research results include:（1）It proves that the permeable sheet piling spur dike has a good flow diversion and sediment diversion function,and the water and sediment conditions are improved by the flow diversion and sediment diversion,and the effect of water and sediment regulation is achieved.The permeable sheet piling spur dike reduces the average velocity of the section behind the dam and the flow and sediment carrying capacity of the section behind the spur dike,:U_B2<U_B1、S_*B2<S_*B1,which plays a role in diversion and sediment separation.With the increase of flow rate,the diversion ratio increases,the diversion effect is obvious,and the sediment ratio decreases;With the increase of sediment particle size,the sediment concentration near the spur dike increases,the distributary ratio increases slowly,and the sediment separation ratio increases;The longer the length of the spur dike,the larger the backwater area in front of the spur dike and the larger the velocity slowing area behind the spur dike,the narrower the river bundle width,and the larger the distributary sediment ratio,the variation of flow diversion ratio is greater than sediment diversion ratio.（2）It proves that the permeable sheet piling spur dike has a good function of sediment retention and desilting effect.With the increase of flow,the sediment concentration in front of the spur dike decreases and the sediment retention ratio decreases,the average sediment carrying capacity in front of the spur dike（8#）is distributed in 0.9～1.4kg/m3;With the increase of flow,with the increase of the desilting amount and the desilting ratio behind the spur dike,the average carrying capacity behind the spur dike（6#）is distributed in 3～4kg/m3.As the effective dam length increases,the backwater area in front of the dam increases,the sediment in the water flow is intercepted,the amount of sediment retention increases,and the sediment retention effect is obvious;As the effective dam length increases,the amount of sediment carried by the water flow increases,the sediment desilting ratio increases.（3）It proves that the permeable sheet piling spur dike has a good beach-making effect.The spur dike spacing,flow,sediment particle size and effective spur dike length on permeable spur dikes with double permeable sheet piling spur dike are analyzed and the curve fitting equation is obtained.and the optimal combination parameters of the double permeable sheet piling spur dike,has emphasized and deepened the value of the water and sediment regulation project of the permeable sheet piling spur dike.The functions of flow diversion and sediment diversion,sediment retention and desilting effect are clear,which proves that the water and sediment control of the permeable sheet piling spur dike is through"division,retention,desilting,construction,and regulation",the water and sediment regulation effect of the permeable sheet piling spur dike is obvious,and the water and sediment regulation of the permeable sheet piling spur dike has a good research prospect and engineering application value.