水流冲刷过程中的边坡临界滑动场及河岸崩塌问题研究

Numerical simulation method of bank collapse based on theory of critical slip field

针对河岸崩塌问题分析和研究,在考虑江河水位升降引起坡外水压力变化及坡内非稳定渗流基础上,同时考虑水流冲刷引起的河床冲深及河岸后退,提出了水流冲刷过程中的边坡临界滑动场和适用于天然江河崩岸的数值模拟,并对水流冲刷过程中的崩岸问题进行了分析。通过对两类不同土质岸坡的崩岸数值模拟,分析了水流冲刷引起的河床冲深及河岸后退过程中坡体的稳定性变化,探讨了不同土质岸坡的崩岸类型及崩塌模式。结果表明,坡度较陡的黏性岸坡崩塌时趋近于平面破坏且通过坡脚;坡度较缓的粉土岸坡崩塌时沿曲面破坏,且在水位骤降过程中易发生局部崩塌。

By improving the critical slip field of slope, the numerical simulation method of bank collapse is proposed, considering lateral erosion and bed degradation. To avoid the unrealistic estimation of pore water pressure distribution, the method proposed here is to couple riverbank stability with groundwater flow simulation, and apply this to deal with the conjunction effect of river stage and groundwater flow. Numerical simulations of clay and silt bank collapse with representative parameters are carried out. With continual lateral erosion and bed degradation, stability of riverbank has dynamic changes. Modes of bank collapse of different soil riverbanks are also discussed. The results show that steep clay riverbanks fail along an almost planar failure surface which passes through the toe of the bank; and a gentle silt riverbank, exhibits a curved failure surface for which may occur partial collapse during rapid drawdown of river water level.