长江江都嘶马段岸崩灾害的形成机理与防治对策

Formation mechanism and prevention strategies of bank collapsing at Sima Bend of Jiangdu in the Yangtze River

江岸稳定性取决于最大崩塌临界机制的驱动力和抵抗力的平衡,二者的平衡又受控于岸边坡形态、岩土组成、水流浪涌特征、植被覆盖等。崩岸是长江嘶马弯道床演变的一个重要方面。通过对嘶马弯道遥感解译图像资料进行对比分析,查清研究区江岸岸线特征及其变迁历程。为了揭示北岸崩塌产生的原因,通过野外踏勘、测量与钻探等技术方法查明该区地质基础条件,并基于实时动态定位技术(Real Time Kinematic,RTK)的水下测量数据建立典型剖面,分析凸岸和凹岸的水流运动特征及其对边岸的影响。从地质基础和水动力条件2个方面揭示嘶马段江岸坍塌形成机理,即具有上细下粗二元结构的边岸地层是岸崩形成的基础,丁坝回流和弯道螺旋流的掏蚀作用是岸崩形成的重要条件。并基于江岸稳定性现状及其发展趋势,提出相应的江岸整治措施。

Bank stability depends on the balance of driving force and resistance of the largest collapse critical mechanism,and this balance is controlled by the shape of shore slope,rock composition,water surge characteristics and vegetation cover. Bank collapse is important for the evolution of the Sima bed in Yangtze River. Based on the interpretation of remote sensing images of the Sima bend,we determined the characteristics of the riverbank shoreline and the transformation of the Sima bend in Jiangdu of Yangtze River. In order to reveal the causes of the bank collapse of the north shore,field reconnaissance,measurement and drilling techniques were used to illuminate the geologic conditions of the study area. In addition,we established typical profiles based on Real Time Kinematic（ RTK）underwater measurement data to analyze flow features of concave and convex banks and their impact on the edge of the shore. The formation mechanism of the riverbank collapse in Sima bend was revealed from the aspects of geological and hydrodynamic conditions.Shore side formation with an upper fine and lower coarse dual structure is the basis for the formation of bank collapse,and the undercutting role of groin recirculation and spiral flow is important for its formation. Based on the current situation and development trend of riverbank stability,we proposed appropriate riverbank remediation measures.