冲砂底孔布置在溢流表孔下方的重力坝的泄流能力分析

重力坝的溢流表孔和冲砂底孔在受到河道宽度限制时，可以将冲砂底孔布置在溢流表孔下方，这种布置其过坝水流运动特性，同时泄流时的泄量，水面线和出口消能特性都会发生变化。本文结合实际工程，通过水工模型试验，对表、底孔单独泄流和同时泄流时的水力特性及其变化进行研究，发现底孔的泄量有所下降，下游冲坑深度有所增加，并且底孔内的水流运动情况也受到一定影响。

An Analysis of Discharge Capacity of Gravity Dams Sand-washing Bottom-holes are Arranged under Overflow Surface Bays

When the overflow surface bay and sand-washing bottom-hole of the gravity dam are limited by the river width, the sand-washing bottom-hole can be arranged under the overflow surface bay. This kind of layout made the motion characteristics of flow over spillway, the discharge flow of both the overflow surface bay and the sand-washing bottom-hole when worked at the same time, water surface profile and the characteristic of energy dissipation below spillway changed. This article is based on practical engineering, it studied the hydraulic characteristics and their changes of the overflow surface bay and sand-washing bottom-hole when they discharged separately and they discharged at the same time. It found that the discharged of the sand-washing bottom-hole decreased somewhat, and the flow motion of the water in the sand-washing bottom-hole was affected.