南渡江过江隧道河段极限冲刷深度预测

Prediction of maximum scouring depth for the Nandujiang River section with a river crossing tunnel

南渡江是我国唯一的一条大型热带河流,其水文等自然条件与我国其他大型河流存在较大差异,河口更是经常受到风暴潮的影响。结合对南渡江海口段过江隧道工程附近水文特征及近期河道演变特点进行分析,利用河工模型试验手段,预测不利水文条件下隧址河段河床的最大冲刷深度。成果表明,工程段河床冲刷主要发生在现状主槽内及司马坡岛的两岸附近,河道等高线总体趋势表现为向两侧推进,主槽宽度加大;受司马坡岛分流、堤防硬边界以及紊乱水流的综合影响,断面最大冲刷深度向下游有增大趋势。预测的极限冲刷深度可为过江隧道的科学埋设提供依据。

Nandujiang River is the only large tropical river in China.Its natural conditions such as hydrology are quite different from that of other large rivers in our country and its estuary area is often affected by storm surges.Combined with the analysis of the hydrological features and recent river evolution characteristics of the Haikou sec-tion of Nandujiang River where the river-crossing tunnel project is located,the maximum scouring depth of the riv-erbed at the tunnel site under unfavorable hydrological conditions was predicted by river model test.The results of prediction demonstrate that riverbed erosion mainly occurs in the current main channel and near the banks of Sima-po Island,and the overall trend of the river contour is to advance to both sides,then the main channel will become wider.Under the comprehensive influence of flow division by Simapo Island,hard boundary of banks and turbu-lence,the maximum bed erosion depth of the section tends to increase downstream.The predicted maximum scour-ing depth is the hasis for scientific embedding of river-crossing tunnel.