Study On Permeating Failure Model And Mechanism In Shijiao Segment Of Beijiang River Levee

Flood was the most harmful natural disaster in China. As a result, dyke system played a very important part in the prevention or control flood project in China. Beijiang River Levee is the first rank in Chinese dyke system. It has suffered flood disasters since the ancient time. Shijiao segment was the first section of Beijiang River Levee. Its floods occurred frequently, especially the piping disaster. So it is realistic and critical to study the permeating failure model and mechanism.In accordance with the piping occurring mechanism controversy, this dissertation analyzed the geologic structure condition of Shijiao levee in detail based on former study. Base on the geologic and hydrologic date, the hydrologic condition and the seepage field were systematically analyzed in this dissertation. And two typical viewpoints to the Shijiao levee piping cause mechanism were contrasted. Secondly, by thoroughly ground investigation, the development sign of the neotectonic fracture on ground were first time found. It provided the ground geology proof for the inference that there was neotectonic fracture in bedrock. In this dissertation the developing characteristic and mechanics quality of the fracture and its control action to the underground water were analyzed. And the neotectonic fracture control flow theory was used to analyze the bedrock structure in Shijiao segment. Then by synthesized the different former isotopic test date and analyzed the bedrock structure with the neotectonics theory, neotectonic fracture in the bedrock which may make it easy to form the collective seepage passageway was found. And the neotectonic fracture controlled the piping occurrence. Finally, finite element method was used to simulate the seepage of stake number 7+330. The results shown that the centralized seepage passage way in bedrock play a very important role in the occurrence and development of piping. So, the centralized seepage passage way in bedrock should be regarded in forecast and prevention of piping in shijiao levee.By theory analyzing and numerical simulating, the controllable function to the piping by bedrock seepage passageway was found. The production provided some useful references to the research of piping in shijiao levee.