Abstract: Overflow of tailings dams is one of the main types of tailings dam accidents. A thorough understanding of the process of tailings dam overflow accidents is of great significance for promoting disaster prevention and mitigation in tailings dams. In response to the engineering safety issues of tailings dam overflow accidents,taking the tailings dam overflow accident in a certain tailings dam in Guangdong Province as a case,this paper systematically analyzed the essential causes of the dam failure and proposed control measures for insufficient flood regulation capacity of tailings dams. Focusing on the essential causes of the failure of the flood control capacity of tailings dams,first,through flood routing calculations and the simplified triangular method,it was quantitatively verified that the maximum flood discharge capacity of the tailings pond′s drainage tunnel is 48. 8 m 3 / s. This capacity meets the requirement to fully discharge a 200-year flood event within 24 hours,confirming that the tailings pond complies with flood prevention safety standards. Secondly,by establishing the judgment criterion of the relationship between the elevation of the drainage well and the top of the initial dam,the positional relationship between the drainage well and the top of the initial dam was explored. It was found that raising the water intake elevation of the drainage well led to the loss of flood regulation capacity of the tailings dam,which was the main cause of this accident. On this basis,three capacity enhancement technologies were proposed:optimizing the slope ratio of the three sections of the deposition beach ( front section >2%, middle section 1. 5%,and water-adjacent section 1%),controlling the sequential construction of the sub-dams (maintaining a height of 2 m),and reserving a buffer space in the transition section (horizontal section≥50 m). These technologies can effectively increase the flood regulation capacity of tailings dams and provide theoretical support for the safe operation of tailings dams. The research results have achieved a transformation from passive emergency response to active prevention and control, and have good reference significance for reducing the risk of tailings dam failure and improving the safety of mining engineering. 

Key words: tailings reservoir,flood overtopping,flood-regulation capacity,drainage system