Abstract: Evaluating the seismic safety of tailing dam involves the liquefaction or even permanent deformation of tailings material at large buried depth in middle and low parts of tailings pond. In this paper, the dynamic strength of tailings sand in large buried depth was tested under different confining pressures (400 kPa, 800 kPa, and 1 200 kPa), and the influenced depth of liquefaction was investigated. Results manifested that the dynamic stress of tailings sand in large buried depth increased with the rising of confining pressure and consolidation stress ratio, while liquefaction stress ratio decreased with the increase of confining pressure. Except for the liquefaction stress ratio under high confining pressure, the rules of dynamic stress and liquefaction stress ratio varying with confining pressure and consolidation stress ratio under high confining pressure are in general the same as those under low confining pressure. According to the liquefaction judgment method recommended in standard, the tailings sand with small dry density and low consolidation stress ratio in the middle of tailings pond are most probably to experience liquefaction. On the contrary, for tailings sand in the bottom, liquefaction can be ignored as seismic stress ratio reduced gradually with buried depth.

Key words: tailings dam, tailings sand, dynamic strength test, large buried depth, liquefaction depth