长江下游扬中环岛崩岸段河势变化及水动力特征分析

Analysis of river regime change and hydrodynamic characteristics of ring island bank collapse in Yangzhong reach of lower Yangtze River

为了预防崩岸的发生,对长江下游扬中河段环形岛屿水动力特性及河势变化情况进行了研究。构建了水动力模型并采用非结构网格中心网格有限体积法求解,对河道断面形态及河坡比变化进行了分析。结果表明:沉船对指南村崩窝处水位、流速场影响不大,崩窝外侧深槽区陡然剧烈冲刷下切是崩窝发生的直接诱因。对于太平洲洲头左右缘、小炮沙左汊出口段、落成洲右汊出口段等部位,应预防大流量级下主流对环岛近岸河床的冲刷,以避免导致岸坡失稳,甚至在滩地狭窄区域直接冲垮洲堤;太平洲洲头左右缘及泰洲大桥左汊大桥下游侧近岸沿岸水流长期流速较大,使近岸河床属于易冲区,应采取措施预防冲刷以免造成边坡失稳。

To prevent bank collapse,the hydrodynamic characteristics and river regime change of the ring island in Yangzhong reach of lower Yangtze River were studied.The hydrodynamic model was established and the finite volume method of unstructured grid center was used to solve the model,and the change of river channel cross-section morphology and river slope were analyzed.The results showed that the shipwreck has little impact on the water level and velocity field of Zhinancun collapse pit,and the sharp scouring and cutting down of the deep channel area outside the collapse pit is the direct cause inducing the collapse pit.The scouring of the near-shore riverbed at the left and right edges of the Taipingzhou head,the left exit section of Xiaopaosha,and the right exit section of Luochengzhou under large flow level should be prevented to avoid bank slope instability and direct collapse of the embankment in the narrow area of the beach.The coastal flow of left and right edges of Taipingzhou head and the downstream side of the left bridge of Taizhou Bridge are under long term large flow velocity,which makes the near-shore riverbed area prone to scouring,so counter measures should be taken to prevent scouring and avoid slope instability.