Research on Protection Method of Overflow Cofferdam for Houziyan Hydropower Station

The cofferdam protection method influences the stability of upstream overflow cofferdam.Taking the overflow cofferdam of Houziyan hydropower station for an example,the sub-weir protection scheme and fuse-plug sub-weir protection scheme are applied for comparative model experiment.The hydraulic characteristic indexes within the upstream cofferdam are measured in the experiment.The influence of cofferdam protection methods on overflow stability of the upstream cofferdam is tested.The results show that both the water level difference between the upstream and downstream side of the upstream cofferdam and the maximum flow velocity of the front of water jump are reduced;meanwhile,the slope of scour hole behind the upstream cofferdam is slowed down,which maintains the overflow stability of the upstream cofferdam effectively and ensures the overflow safety of the upstream cofferdam in the flood season.