Yang Jun, Jia Dongdong, Zhai Biyao, Chen Xiaona, Wang Jinyang
Key Laboratory of Port, Waterway and Sedimentation Engineering of Ministry of Transport, Nanjing Hydraulic Research Institute, Nanjing 210029, China.
The National Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing 210098, China.
Heliyon. 2024 Sep 6;10(17):e37448. doi: 10.1016/j.heliyon.2024.e37448. eCollection 2024 Sep 15.
Bank erosion is a key feature of channel evolution in alluvial rivers, and will occur under the combined effect of hydraulic erosion and frost heave/freeze-thaw process of rivers in seasonal frozen regions. However, most research on bank erosion modeling has seldom considered the impact of the frost heave/freeze-thaw process. Therefore, the variation in the mechanical characteristics of riverbank soil under the freeze-thaw cycle was investigated firstly in the current research and then used in the modeling of bank erosion processes at typical sections of the Songhua River. Additionally, a sensitivity analysis of riverbank stability was conducted using orthogonal experiments. The results indicate that after 7 freeze-thaw cycles, the soil cohesion and internal friction angle of bank soil decreased by about 10%-47 % and 9%-19 %, respectively. Unlike lowland rivers, bank erosion of rivers in seasonal frozen regions is more likely to occur during the rising water period. The frost heaving/freeze-thaw process will make the bank stability safety coefficient more quickly decrease to the unstable critical value. As compared with the case without considering the frost heaving/freeze-thaw process, the mass failure occurred in advance when the frost heaving/freeze-thaw process was considered, and the calculated bank erosion volume was increased by 11%-51 %, agreeing better with the measured value. The sensitivity ranking of the four influencing factors on riverbank stability under freezing-thawing conditions is as follows: river stage > groundwater level > cohesion > internal friction angle. The current study can provide a reference for research on bank erosion and channel evolution of rivers in seasonal frozen regions.
河岸侵蚀是冲积河流河道演变的一个关键特征，在季节性冻土地区，河流的水力侵蚀和冻胀/冻融过程共同作用下会发生河岸侵蚀。然而，大多数河岸侵蚀建模研究很少考虑冻胀/冻融过程的影响。因此，本研究首先考察了冻融循环作用下河岸边坡土体力学特性的变化，然后将其应用于松花江典型断面的河岸侵蚀过程建模。此外，利用正交试验对河岸稳定性进行了敏感性分析。结果表明，经过7次冻融循环后，岸坡土体的黏聚力和内摩擦角分别降低了约10%-47%和9%-19%。与平原河流不同，季节性冻土地区河流的河岸侵蚀更易发生在涨水期。冻胀/冻融过程会使河岸稳定性安全系数更快地降至不稳定临界值。与不考虑冻胀/冻融过程的情况相比，考虑冻胀/冻融过程时，大规模破坏提前发生，计算得到的河岸侵蚀量增加了11%-51%，与实测值吻合度更高。冻融条件下影响河岸稳定性的四个因素的敏感性排序如下：水位>地下水位>黏聚力>内摩擦角。本研究可为季节性冻土地区河流的河岸侵蚀及河道演变研究提供参考。
