Research On Breaking Mechanism Of Upstream Tailing Dam Under The Flood

The flood is an important sensitive factor in tailings dam breaking, and overtopping flood is the third factor which can cause the breaking disaster of the tailings dam, and overtopping flood ranks after the instability and the earthquake. Therefore, studying the failure mechanism of the tailings dam under the action of the flood, and coming up with the corresponding prevention and control measures of debris flow caused by the dam breaking is very necessary and urgent.The paper carries out the research based on the upstream tailings dam, Shen Jia Cun tailings dam engineering example by Duomude processing factory of titanium in Fumin County, Yunnan Province. It mainly includes the stability analysis of the tailing dam under the normal and flood condition, the effect of the instantaneous dam breaking and the gradual dam breaking of the upstream tailings dam in the action of flood and the debris flow research caused by dam breaking. The specific content of the study are:(1) internal friction angle and cohesion index value of the related materials of the tailings are got by the field test and the indoor direct shear test of the tailings based on engineering geological investigation data of Shen Jia Cun tailings dam; (2) the Swedish slice method, Bishop method and finite element strength reduction method are adopted in the stability analysis of 2D and 3D model of Shen Jia Cun tailings dam, and the equivalent linear model is adopted in the dynamic time-history analysis(3) instantaneous dam breaking rules of Shen Jia Cun tailings dam are studied based on the fluid dynamics and Bingham fluid model theory; (5) gradual dam breaking rules of Shen Jia Cun tailings dam under the overtopping flood are studied based on the OSMAN breaching developing theory; (6) the corresponding debris flow retaining measures are proposed.The research results show that:(1) the limit equilibrium method and the finite element strength reduction method showed that Shen Jia Cun tailings dam can function safely and stably in normal working conditions, especially under the condition of flood, eliminating the influence of dam stability factor to the dam beaching in overtopping flood action. (2) The finite element dynamic time history analysis shows that the safety factor of the tailings dam under earthquake action is insufficient, which may occur in the failure of the dam sometime. (3) instantaneous dam breaking of Shen Jia Cun tailings dam can cause tremendous damage to the bridge structure and settlement downstream the Shen Jia Cun tailings dam due to the short arrival time of the debris flow and the bigger peak height, in order to safeguard the people’s life and the safety of property, once early discovered,early warning should be given to strive for the evacuation time in maximum extent. (4) gradual dam breaking of Shen Jia Cun tailings dam last longer, but if corresponding measures are not taken, gradual dam breaking will cause serious disasters finally; (5) breach will appear collapse under the action of water flow and the landslide will produce the breaking wave evolutioning downstream the dam, the flood peak caused by the dam breaking wave will create a hazard to downstream; (6) the water surge formed by collapse of the breach, and the larger shear stress distribution at the both sides of the top of the breach caused by dam breaking flow are not conducive to stability of the breach slope, resulting in a the larger collapse of breach slope.The innovation of this paper include:the analysis results are more in line with the actual because of carring out the gradual dam breaking analysis and research of the tailings dam in the OSMAN breach theory.