中国北方季节性冰冻河流岸滩崩塌数值模拟——以松花江为例

季节性冰冻河流（季冻区河流）受水动力-冻胀/冻融耦合作用，岸滩崩塌机理复杂，且对河道演变具有重要影响。通过建立水动力-冻胀/冻融耦合作用岸滩崩塌力学模式，以中国东北地区松花江干流大顶子山航电枢纽下游近坝段为例，开展季冻区河流岸滩崩塌及河道演变的三维数值模拟分析。研究结果表明:岸滩坡脚侧蚀主要由水力冲刷所控制，冻胀作用使岸滩开裂深度增加，冻融过程则会使岸坡土体力学强度降低，影响岸滩稳定；岸滩崩塌对季冻区天然河流演变具有显著影响，考虑岸滩崩塌的模拟结果与天然实测结果基本吻合，可较好地模拟河床冲淤、岸滩崩塌所引起的河道演变过程。研究成果可为季冻区河流岸滩崩塌及河道演变的深入研究提供技术支撑。

Numerical simulation of bank erosion in a typical seasonally frozen river-case study of the Songhua River,China

Bank erosion in the seasonally frozen river (SFR) is subject to the coupling effects between hydrodynamic forces and frost heave/freeze-thaw, and the mechanism is complex. Bank erosion plays an important role in channel evolutions of the SFR. Taking the downstream near dam section of the Dadingzishan Navigation and Hydropower Project in the mainstream of the Songhua River as an example, a bank erosion model coupling hydrodynamic forces and frost heave/freeze-thaw interaction was developed. Bank erosion and fluvial processes in this typical SFR were simulated by the numerical model. The results indicated that the lateral erosion at the bank toe was mainly controlled by hydraulic forces. The cracking depth of the riverbank increased due to the frost heave effect, and the mechanical strength of riverbank soil reduced because of the freezing and thawing process, which has great effects on the stability of riverbanks. The simulation results of bank erosion were in agreement with the measured data, which demonstrated that the numerical model could simulate the complex channel evolution processes caused by river bed scour as well as bank erosion. This study could provide technical support for the in-depth study of bank erosion and channel evolution in the SFR.