Study on tailings dam over-topping failure model test and break mechanism under the rainfall condition

摘要

Based on self-designed tailings dam simulation experiment device of tailings dam-break, experimental study of tailings dam failure was carried out under the condition of rainfall. The change rule of infiltration line, the developing process, the mechanism of dam failure and the displacement of the dam body after collapse were obtained and recorded by the rainfall devices, the infiltration line measuring devices, the displacement monitoring devices and the camera. The results are as follows: in the early stage of rainfall, the changes of the infiltration line in the front reservoir and the outside slope of the dam were obviously lagging behind the water level, but in the middle and tail of the reservoir it was not obvious. In the later stage of the rainfall, the lagging phenomenon gradually disappeared, and the change of water level had an obvious effect on the change of infiltration line. At the early stage of the dam failure, seepage and water overflow occurred on the outer slope of the tailings dam, causing local collapse to occur. In the late stages of dam break, the water flew over the dam crest and continued to erode the dam body, thus lead to the dam failure. Under the action of seepage force, the phenomenon of piping occurred in the dam. With the continuous erosion of water flow, the seepage force, floating severe, buoyancy force and pore water pressure were increased, the anti-resistance was weakened and the stability of dam was reduced. After the dam failed, the settlement displacement in the breach was the largest, in addition to the breach, the settlement displacement occurred mainly at the dam abutment. The external expansion occurred mainly in the middle dam and dam foot. The research results provide some valuable guidance and reference for the mechanism analysis of the tailings dam-break, the disaster prevention and controlling when subjected to rainfall.