论文部分内容阅读
采用双向稳定水流、清水定床、局部动床的试验方法 ,用正态模型研究长江口深水航道整治一期工程南导堤丁坝群坝头局部冲刷问题。结果表明 ,航道开挖和双丁坝的存在使得下游流速有所增加 ,影响程度落潮大于涨潮。坝头局部冲刷主要受落潮流控制 ,在沿深度为单一粉砂底质情况下 ,坝头冲刷坑深度分别达到 2 7m和 2 9m ;考虑到原状底质下部为极难起动的粘土 ,实际冲刷坑底界到达粘土层后就不再刷深 ,此时冲刷坑深度为 7 4m和 4 7m ,冲刷坑的平面范围有所加大。工程设计提出的护坦尺度能较好地保护坝头前沿滩地 ,适当缩小护坦尺度也能起到保护作用 ,但冲刷范围明显增大。
Using the test method of bidirectional steady flow, fixed bed of water and partial moving bed, the normal scouring of the dikes on the south dike dams in the first stage of the Yangtze Estuary Deepwater Channel Regulation Project was studied by the normal model. The results show that the channel flow and the existence of double-dams make the downstream velocity increase, and the ebb and flood of tidal flats is larger than that of high tide. The local erosion of the dam head is mainly controlled by the falling tide flow. When the depth is a single silt bottom, the depth of the scour pit of the dam head reaches 27m and 29m, respectively. Considering that the lower part of the intact sediment is extremely difficult to start, the actual erosion After the bottom of the pit reaches the clay layer, it will no longer brush deep. At this time, the depth of the scour pit is 7 4m and 4 7m, and the area of the scour pit is enlarged. Engineering design proposed protection tank standard can better protect the front of the dam beach, appropriate to reduce the scale of protection tank can also play a protective effect, but the scope of erosion increased significantly.