| Since the 21 st century,China's mining and metallurgical industry has developed rapidly.The tailings generated in the beneficiation process not only occupy land,but heavy metal ions in the tailings also cause huge pollution to rivers,lakes and groundwater.At the same time,the safety and stability of tailings dams have also become the bottleneck problem restricting the development of mining industry,so the treatment of tailings needs to be solved urgently.On the other hand,with the rapid development of the automotive industry,a large amount of waste tires are produced every year,and unused waste tires have a serious impact on the natural ecology and people's lives.Based on the realistic background of the large accumulation of tailings and waste tires and the current situation of low comprehensive utilization,considering the tires have a series of advantages such as low density,light weight,small deformation modulus,good shock absorption and vibration isolation effects,the mixed soil made by mixing waste tire particles into tailing sand is used in geotechnical earthquake resistance and disaster reduction and other engineering fields to solve the problem of comprehensive utilization of two solid wastes.In order to study the effect of shock absorption and isolation of waste tire particles-tailing sand mixed soil,the dynamic characteristics of the mixed soil were studied using the GDS dynamic triaxial test system.The main research contents and results are as follows:(a)By analyzing the dynamic strength curve and dynamic stress-strain curve of the mixed soil,and using the Hardin-Drnevich model to fit the backbone curve of the mixed soil.It is concluded that the dynamic strength of the mixed soil decreases after blending the tire particles,and the greater the tire particle content,the more the strength decreases.The nonlinear characteristics of the dynamic stress-strain curve of pure tailings are obvious,while the linear characteristics of the backbone curve of the mixed soil are more obvious.(b)The dynamic characteristic parameters such as dynamic elastic modulus and damping ratio of mixed soil are studied,and the effects of tire particle content and lateral consolidation pressure on dynamic elastic modulus and damping ratio are discussed.The interaction mechanism of the mixed soil particles is analyzed,and the critical tire particle content range is determined to be between 4% and 8%.Within a certain range of tire particle content,the decrease of the dynamic elastic modulus of the mixed soil and the increase of the damping ratio are conducive to its advantages of shock absorption and isolation.The results can provide a reference for the application of waste tires in engineering fields such as earthquake resistance and disaster mitigation.(c)By analyzing the relationship between axial dynamic strain and vibration cycle,the deformation growth characteristics of the mixed soil under dynamic load are obtained.With the increase of the cyclic stress ratio and the amount of tire particles,the growth rate of the sample deformation increased significantly.Different from the law of deformation and growth of pure tailings,the axial strain of mixed soil increases almost linearly.(d)The relationship curve between pore pressure ratio and cycle times of mixed soil was analyzed to obtain the development characteristics and influence laws of dynamic pore water pressure of mixed soil.The dynamic pore pressure rise and cumulative speed of the mixed soil are obviously accelerated,but the pore pressure ratio is lower than that of pure tailings when the mixed soil is damaged.The pore pressure ratio is about 0.9,0.8 and 0.7 respectively when the mixed soil is damaged with 4%,8% and 12% tire contents,indicating that the antiliquefaction ability of soil can be improved to a certain extent by adding the right amount of tire particles.The improved Seed model and hyperbolic model were used to correlate the dynamic pore pressure growth curve of mixed soils to obtain the pore pressure model parameters. |
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