Study On The Change Of Mechanical Properties Of Metallic Tailings With Initial Parameters Under Drying And Wetting Circulation

Because the tailings dam is affected by natural weather such as rain and snow,the repeated rise and fall of the location of the saturation line in the dam makes the tailings in the dam always in an environment of repeated wet and dry cycles.This cyclic effect directly affects the settlement and deformation of the tailings dam.The mechanical properties will have a negligible impact on the stability of the tailings dam.Therefore,it is of great significance to study the mechanical properties of tailings sand under the effect of wet-dry cycle for the safety evaluation of tailings dam.In this paper,based on particle fraction test,moisture content test,compaction test and indoor triaxial compression test,the effect of different initial moisture content and dry density on tailings sands subjected to different dry-wet cycles is analyzed and analyzed.Processing and comparing the results yields the following conclusions:(1)Samples of tailings with different moisture contents were subjected to undrained shear tests after experiencing different numbers of cycles of moisture absorption and desorption,and the stress-strain curve was analyzed.The results showed that the stress-strain curve did not occur with the increase in the number of times.Reversal of change.Dry and wet cycle will make the tailings strength weaken,with the increase in the number of cycles decreases,in the general experience 3 to 5 times after the intensity tends to be stable.(2)During the shearing process of the tailings sand samples with different water and moisture cycles,the pore pressures showed a change rule of increasing first and then decreasing.In the early stage of shearing test,the pore water pressure increases with the increase of axial strain.When the axial strain reaches a certain value,the pore water pressure reaches its peak value.After that,with the further application of the load,the pore water pressure decreases to appear.Negative values tend to be stable.(3)With the increase of the number of dry-wet cycles,the pore water pressures of all the moisture content tailings samples showed an increasing characteristic.At the same time,the axial strain at the pore water pressure of 0 increased with the number of times,that is,at the shear.During the process,the critical point of the specimen from shearing to clipping characteristics increases with the number of cycles,indicating that the wet-dry cycle changes the dilatancy and shear characteristics of the specimen.(4)After six cycles of dry-wet cycles,the peak deviator stress is reduced by 20% to 30% compared to the non-recycled sample,and the value of the sample under very few conditions drops to about 40%.In the initial stage of loading,the initial stiffness of the specimen decreases with the increase of the number of cycles,and the value decreases obviously after the first cycle.(5)The dry density of 1.53g/cm3 sample pore pressure was less affected by the number of wet and dry cycles,while the dry density of1.61g/cm3 and 1.66g/cm3 sample pore pressure development was greatly affected by the number of cycles.And the same dry density sample after undergoing different number of dry and wet cycles,the pore pressure curve will have a greater change,after the number of wet and dry cyclesreaches 4 to 5 times,indicating that the dry density and wet and dry cycle will affect the tailings sand shrinkage characteristics.