The 4th International Symposium on Mine Safety Science and Engineering (ISMSSE2018)

247 / 2018-05-09 03:43:21

Shear Behaviour of ultra fine magnetite tailings subjected to freeze-thaw cycles

matric suction; tailings dam; shear strength; SWCC; cohesive force

Mine Dynamics Disaster > tailings pond

This paper discusses results of tests performed on ultra fine magnetite tailings subjected to freeze-thaw cycles. The unconsolidated and undrained shear tests were conducted on tailings subjected to various rates of freeze-thaw cycles with different under confining pressures. Using the freeze-thaw cycle times, cooling temperature, initial dry density and moisture content as four main influence factors of shear behavior of the tailings samples, the shear stress-strain curve type, compression modulus, failure strength, cohesion and internal friction angle were measured. The results shows that the freeze-thaw cycle has weakening effect on the shear behavior of the tailings samples, and the shear mechanical parameters are also impacted by a combination of confining pressure, freeze-thaw cycle condition and initial physical-mechanical properties of the tailings samples. The outcome of these tests shows that the freeze-thaw cycle mainly affects the porosity, bound water and arrangement of the tailings particles. After that, the macroscopic changes in the shear strength indexes emerge which may lower the stability of the tailings dams or dykes.