Research On The Mechanical Characteristics Of The Unsaturated Tailing Sand

In recent years,the utilization and development of tailings have played a vital role in China's economy.The safety of tailings dams is also becoming more and more prominent.Tailings dam is liable to collapse due to climate,environment and humanities,causing casualties and national economic losses.Therefore,the physical and mechanical properties of unsaturated tailings are studied in this paper.Combining experimental data.FLAC 3D is used to investigate the influence of saturation on the safety of tailings dam.This paper focuses on fengshuigou tailings in Anshan city,Liaoning province,Liaoning Province.The physical properties and mechanical properties of tailings sand were studied by screening experiments and triaxial experiments.In the screening experiment,it was determined that the tailings sand sample belongs to medium sand.In triaxial experiments,By controlling different water contents(11%,13%,14%,15%,17%),different dry densities(1.75g/cm~3,1.80g/cm~3,1.85g/cm~3,1.90g/cm~3),different particle sizes(coarse sand,medium sand,fine sand),obtain the stress-strain relationship curve and the influence of tailings sand on cohesion and internal friction angle under different conditions.For unsaturated tailings with different water content,the cohesion value reaches the maximum when the water content reaches 14%.Then the cohesive force decreases with the increase of water content.The internal friction angle gradually decreases with increasing water content.For unsaturated tailings with different particle sizes,due to the composition of tailings particles,the cohesive force increases with the increase of particle size,while the internal friction angle is less affected by it.For unsaturated tailings with different dry densities,the internal friction angle and cohesion increase with the increase of dry density.Comparing the mechanical properties of saturated and unsaturated tailings,it is known that the pore pressure of saturated tailings is greatly affected by strain,and the unsaturated tailings are less affected by it.Eight parameters of two kinds of sand samples were obtained by Deng-Ken Zhang model,and it was concluded that the saturation degree of tailings sand had a great influence on cohesion,the modulus of coefficient,and material parameters.Combined with the actual situation of the tailings dam,the numerical simulation analysis of the Fengshuigou tailings dam is carried out by FLAC 3D software to simulate the influence of the saturation degree of the dam on the safety of the tailings dam under the action of gravity.It is concluded that saturation has little influence on the safety of dam.