Experimental Study On Steady - State Characteristics Of Saturated Tailings

The Steady-state strength of saturated tailings is the key factor whether tailings dams willstream sliding damage. Thus, it is necessary to clarify the Steady-state strength characteristicsof tailings to reveal the mechanism of tailings dam sliding failure. The function of dynamic is topromote water pressure rise and reducing the effective stress of soil. The sliding damage afterearthquake liquefaction flow are often caused by static load stress, so the Steady-state strength(or residual strength) can be determined under static loading conditions.This article adopts consolidated undrained triaxial test, by preparing specimens from sixdifferent relative density tailings, after saturation in the experiment under confining pressure100kpa,200kpa,300kpa. During shearing, the confining pressure maintain constantly.At thesame time,the axial shear forces increase gradually. At last, the shear forces are maximum.However, the experiment will be continued until the sample’s axial strain deviate to25%.Moreover according to the Standard for Test Methods of Geo-technique for sieve analysis oflaw, to the size of the value to the variable, artificial tailings of three kinds of particle sizedistribution of sample preparation. In the case of initial relative density and confining pressureconsistent, consolidated undrained shear test separately until into a steady state.According to the results, draw out different confining pressures, sample density, particlesize distribution of tailings under-stress-strain relationship between pore water pressure curve,establish a steady line of saturated tailings, and find the steady internal friction angle of tailingsand Steady-state strength of expression. Get the following results:(1) Consolidation of saturated tailings there are three typical types of undrained shearingcurve: softening type, type quasi-softening and hardening type. One of saturated tailings ofloose cut curves with apparent softening, specimen in axial strain grows to about15%-20%reach steady-state deformation. In the early shear and axial strain and pore water pressureincrease with increasing shear stress. After the peak shear stress drop in the last stable after youreach the maximum pore water pressure has remained stable.(2) Specimen of the same grade, the same percentage of void, with the increase ofexperimental ambient pressure, shear softening the curve gradually reduced, tailings steadypoint rose. With a gradation and sample different than the pores in the200kpa cut curves areshown under confining pressure and strain softening, and as pore pressure decreases, shearsoftening of the curve gradually weakened.(3) Steady-state is an inherent properties of tailings, not under the influence of externalconditions, related to the particle size distribution of the tailings. Within arithmetic coordinatesof pore pressure and shear stress, steady line is a tailings line, part of the above, on behalf of the shear shrinkage of tailings in the actual slide the case of liquefied flow is likely to occur.Average particle size of tailings, its steady-state angle of internal friction, and spatial location ofhigh steady-state line. Therefore, under the condition of fine grained tailings in force-inducedliquefaction flow more easily sliding damage.