水库大坝溃决水流在一定程度上可以概化为矩形水柱瞬间溃塌水流，本文通过建立重力作用下矩形水柱瞬间溃塌的数学模型，模拟研究矩形水柱瞬间溃塌的水流特性，并基于量纲分析法得到了溃坝过程中坝址处的流量公式，对比分析了不同深宽比时坝址处流量的变化过程。研究表明：当深宽比相同时，坝址处的流量变化规律一致；当深宽比不同时，峰顶流量随着深宽比的增大而减小，且其出现时刻延后。同时，在此基础上推求得到了基于深宽比的坝址峰顶流量公式及峰顶流量出现时刻公式，得到了公式中峰顶流量系数及时间系数与矩形深宽比n的关系。研究结果可为溃坝水流问题的研究提供借鉴。

To some extent, the flow of dam break in the reservoir can be generalized to collapsed water flow in rectangular column. A mathematical model for dam-break flow under the action of gravity in a rectangular water column has been set up to study the flow characteristics in dam site，moreover，a discharge formula in dam site during the process of dam-break was obtained by dimensional analysis method and the discharge change process in dam site was also analyzed by comparing the different ratio of depth to width. The results showed that the rule of discharge change process in dam site is uniform at the same ratio of depth to width; the peak discharge decreases and the occurring time delay as the ratio of depth to width increases at the different ratio of depth to width, then the discharge formula of peak discharge and occurring time based on the ratio of depth to width is derived and the relationship among peak discharge coefficient, occurring time coefficient in the formula and the ratio of depth to width is also analyzed. The results can provide references for the research of dam-break.