Mechanical Properties of Riverbank Soil in the Jingjiang Reach and the Characteristics of Flow in Pocket Collapse Area

Based on analyzing the field data and the experimental results, Mechanical properties of riverbank soil in the Jingjiang Reach and the characteristics of flow in the region of pocket collapse are discussed. It is calculated that riverbank of the Jingjiang Reach is characterized by a typical composite structure, covering the low liquid limit cohesive upper layer and the sandy lower layer. The cohesion of the cohesive soil increases first and then decreases with the increase of water content. The internal friction angle generally decreases with the increase of water content. The flow structure in pocket collapse area shows the intensive three-dimensional characteristics. The surface and vertical average velocity, the range and strength of the reflux increase with the increase of upstream flow discharge. Under different conditions of flow discharge, the vertical average velocity in pocket collapse area has a distributed feature of nearly linear or tiny oscillation along the relative direction of water depth. The research can provide the technical support for prevention measures of bank collapse. (paper)