凤仪场航电枢纽工程施工导流二期纵向围堰结构型式比选

Type selection of longitudinal cofferdam for 2nd stage construction diversion of Fengyichang project

凤仪场航电枢纽工程主要泄洪建筑物由3孔冲沙闸和19孔泄洪闸组成,坝轴线长度约657m,河床覆盖层厚度10～16m,工程施工分两期三段进行,一二期导流标准均为10a,围堰挡水时段为枯水期,经计算和2次导流模型试验,汛期围堰表面最大水流流速5.6～7.4m/s,基本为钢筋笼、铅丝笼的抗冲刷流速,因此凤仪场二期纵向围堰采用砂砾石填筑,根据围堰表面流速大小,分部位用大块石和钢筋笼防护。

The flood releasing works of the Fengyichang navigation and generation project mainly consist of 3 sand sluicing gates and 19 flood releasing gates. The dam axis is about 657m long and the river bed overburden is 10 - 16m thick. The project will be constructed at two stages using a 10a flood control standard for the 1st and 2nd stage diversions. The cofferdam will retain water at dry flow period. Through calculation and 2 diversion model tests, the maximum overflow velocity is 5.6 -7.4 m/s at wet period,which is basically the flow to use reinforcing cages and gabions to resist scouring. Therefore, the 2nd stage longitudinal cofferdam will be filled by sand gravels and protected by large blocks and reinforcing cages at different parts based on the cofferdam overflow velocity.