Research Of Shear Strength Characteristics For Saturated Tailings Under High Stress

It has obviously differences between the shear strength of tailings under high stress and low stress. In the natural environment, the fines are widely existed in all of the soil materials and have influence in the mechanical properties and shear strength. In order to analyse the actual safety condition of tailing dam, adopting laboratory test to determine the related mechanics parameters of tailings materials is very important.Several saturated specimens from same tailings were conducted consolidated undrained test, under 4 different groups of confining pressure. According to the Standard in Test Methods of Geo-technique for sieve analysis, the contents of the particle size below 0.075 mm as the variable, artificially preparation 6 kinds of samples with different fine contents, and then the consolidated undrained triaxial test was conducted with 3 different shearing rates under several groups of confining pressures, until the samples get into a collapse state. Main works and the results are as follows:(1) According to the test results, the stress-strain curves with different confining pressure was drew, and then choice the amended hyperbolic model better for describing the relationship between stress and strain of the tailings under high stresses.(2) The comparison results between quadratic parabolic and power function of envelope lines showed that the power function of Mohr envelope has high precision as the criterion of breaking strength for tailings sand under high stresses.(3) Both the peak strength and the softening decreases as the confining pressure increased, and the development of the pore water pressure represses as the fine contents increased. Within the shearing rate range of the test, the variation of the shear strength peak of the tailing samples under same confining stresses are first increased and then decreased as the shearing rate enhanced, and the softening monotone increased.(4) The specific changes of granule contents were caught by sieving the samples before and after test. Grain crushing increases as the confining pressures increased and decreases as the fines contents decreased. Bg and Br were adopted for describing the level of grain crushing and analysis it, same conclusion we can see, there has grows with the power function between the parameters for describing the level of grain crushing and the confining pressure.