Mechanism Of Bank Collapsing At Sima, Jiangdu Along Yangtze River And Its Prediction Method

With the application of the underwater topographic monitoring data provided by Bureau of Water Conservancy of Jiangdu, a three-dimensional dynamic model describing the variation of riverbed at Sima is firstly established by the use of ArcGIS, then the development process of underwater slope at Sima is researched. According to the entire distribution law of bank collapse along middle and lower reaches of Yangtze River, combined with the concrete geological and hydrogeological condition of Sima curved riverbank, the mechanism and affecting factors of bank collapse are researched. In addition, the following research work has also been done: (1)On the basis of appropriate geological model and related parameters being chosen, the stability of underwater slope at Sima is researched in details, in this research different cases are considered, such as different altitudes of embankment, different gradients of slope, different damage types of both toe damage and surface damage. The effects of stones for reinforcing the slope surface on the stability of slope are also researched as well as the effects of soil mechanical parameters. (2) According to the current data, both the critical flow velocity and critical shearing stress of soil layer and surface stone resisting the erosion of water are studied, in which the influence of inclination on critical flow rate and critical shear stress is also carefully considered. (3) By use of different kinds of methods, the knowledge about the mechanism and the related influence factors of bank collapse at Sima curved conduitis is developed. Combined with the research about the influence of the project of T-dam and riprap protection, an adequate cognition about the present status of Sima bank is obtained, and a suitable clew for predicting bank collapse of Sima is established. (4) Based on the GIS model of underwater topographic monitoring, the forecasting model and forecasting method for strip collapsing and arc collapsing of slope with surface stone layer are presented, the forecast chart of both trip collapsing and arc collapsing with the consideration of the Yangtze hydraulic condition and beach angle are given.