Influence of the freeze-thaw effect on the seasonally frozen riverbank stability: A case study of the typical reach of Songhua River, China

Abstract

岸滩侧蚀崩塌现象普遍存在于江河湖泊中，是一种危害较大的自然灾害。季节性冰冻河流受水动力、冻融耦合作用，岸滩崩塌机理复杂，开展其岸坡稳定性研究对河势控制和河流综合治理具有重要意义。以松花江干流大顶子山航电枢纽下游近坝段为例，采用BSTEM断面尺度模型，对河岸崩塌过程进行了模拟，定量分析了冻融作用对河岸稳定性的影响。研究结果表明：涨水期河岸稳定性相对较高，洪水期和退水期稳定性相对较低，为崩岸多发时期；冻融作用会使河岸稳定安全系数F_s提前达到不稳定临界值，即与不考虑冻融作用相比，河岸提前崩塌，且考虑冻融作用的崩塌宽度更接近实测值，累计冲刷崩塌总量增幅约为7%~41%。研究结果可为季节性冰冻河流岸滩崩塌及河道演变研究提供一定借鉴和参考。;The phenomenon of lateral erosion and collapse of bank is widely distributed in major rivers in the world, which is a kind of natural disaster with great harm. Seasonal frozen rivers are affected by the coupling of hydrodynamics and freeze-thaw, and the mechanism of bank collapse is complex. The research on the collapse process is of great significance to river bank protection and comprehensive river management. Taking the downstream part of the main stream of the Songhua River near the dam of Dadingzishan Aviation Power Project as an example, the BSTEM model was used to analyze the bank slope stability in different periods by considering the freezing and thawing effect, and the collapse process of the dual structure bank was simulated. The results showed that the stability of the river bank was higher in the dry and high water periods, and the stability was lower in the flood period and the receding water period, which was the stage of frequent bank collapse. Considering the freezing and thawing effect, the simulated river bank slope shape and collapse width were in good agreement with the measured values, and the amount of erosion and collapse was increased by 7%-41%. The research results can provide some reference for the study of river bank collapse in seasonally frozen areas.