河岸窝崩机理的探讨

Study on Ω caving mechanism in alluvial rivers

通过分析窝崩发生的特点,本文给出了窝崩发生的边界条件、水流条件和触发因素的具体内涵。边界条件包括岸滩结构的不连续性、岸滩抗冲能力差等,是发生窝崩的必要条件和内因;水流条件是指局部强烈的紊动结构(环流、斜流、横流)、深泓靠岸、洪水涨落等,是窝崩发生的重要条件;水压力的突变、突加荷载、地震等是窝崩发生的激发条件。窝崩发生的原因主要是岸滩剧烈淘刷或岸滩土体的承载能力减小或消失;按窝崩成因,可分为淘刷窝崩和液化窝崩。

By analyzing the field data on Ω caving, the concrete conditions to cause Ω caving were given in this paper, including boundary conditions, flow conditions and triggering factors. Boundary conditions, which include the uncontinuity of the bank material composition and the anti-eroding ability of the bank soil, are the essential and internal cause of the Ω caving. Flow conditions, which include strong flow structures（ such as circulation, turbulence, oblique flow and crosswise flow）, channel regime near the bank and changes of the water level, are important for the Ω caving. Factors like a sudden change in the water pressure, a sudden load and an earthquake are triggering conditions. The main reasons to cause Ω bank failures are the strong cave-in and the soil liquefaction of the bank. Therefore Ω bank failures are usually divided into two types： the caving failure and the liquefaction failure.