It is necessary for stability analysis of high tailings dams to grasp the strength property of tailings material under high pressures. The theoretical derivation of a general power function based on the Mohr criterion must satisfy restrictions {

}. The high stress traixial test results indicate that the power function of Mohr criterion reflects the strength characteristics of tailings material well under high pressures. The grain-size distribution curves of the pre- and post- test show that tailings material particles will crush in the cutting process when the confining pressure reaches or exceeds the threshold value. The threshold value for tailings silt of copper mine in Dexing is 1 200 kPa

and for tailings sub-silt of copper mine in Dexing is 1 600 kPa. Research results can provide the theoretical basis for the stability analysis of high tailings dams.