Abstract:

A tailing seepage failure testing instrument designed by the authors was used to simulate the whole process of tailing seepage failure under the condition of increasing upstream water level and continuous increase of hydraulic gradient. The evolution of the pore water pressure and flexural guided wave parameters, as well as the flexural guided wave signals' b-value and fractal dimension during the experiments, were analyzed. The evaluation criteria of tailing seepage failure level were proposed based on the change characteristics of pore water pressure and flexural guided wave characteristic parameters. The results show that: (1) During the tailing seepage failure process, the pore water pressure increases with the increase of hydraulic gradient, but when the hydraulic gradient increases to a certain degree, the pore water pressure will show a sudden drop. (2) Tailing seepage failure is a gradual process, and the flexural guided wave parameters in this process can be classified into four types: no signal, weak signals, strong signals, and violent signals. The four types of signals correspond to the ordinary operation stage, development stage, pre-damage and final seepage failure stage of tailings, respectively. (3) The b-value and fractal dimension of the guided waves are at a low level before the final seepage failure stage of the tailings and violently oscillate when the final seepage failure is approaching. (4) Through the analysis of the flexural guided wave parameters, the quantitative indices of the tailing seepage failure degree are proposed, and the tailing seepage failure is divided into four warning levels. The four warning colors of blue, yellow, orange and red represent the corresponding warning level.

Key words: tailings, seepage failure, pore water pressure, flexural guided wave, early warning