| The incineration slag of domestic waste power plant(hereinafter referred to as "slag")has a significant impact on the mechanical properties of ultra-fine tailings.Adding slag to ultra-fine tailings plays an important role in improving the stability of dam and the operation safety of tailings pond.Taking an alumina ultra-fine tailing in Nanchuan,Chongqing and incineration slag of a domestic waste power plant in Chongqing as test materials,starting from the mechanical characteristics analysis of the ultrafine tailings-slag mixed stack(hereinafter referred to as the "mixture"),the particle size analysis,direct shear test,triaxial test,consolidation test,permeability test and erosion test of the ultra-fine tailing slag mixed specimens with different slag content were carried out respectively,The influence of slag on the early mechanical properties of ultra-fine tailings accumulation is revealed;The micromechanical properties of the mixture were studied based on PFC discrete element numerical simulation software.The specific research results are as follows:1.Through the straight shear test and the triaxial test,the stress-strain curve of the mixture with slag content of 00% ～ 70% is obtained.With the increase of slag content,the plastic strain failure mode gradually changes to strain softening failure mode;The shear strength and stress difference of the mixture containing slag are greater than that of pure ultra-fine tailings;The variation law of shear strength index(internal friction angle and cohesion)of mixture with slag content is roughly the same.The cohesion of the mixture increases first,then decreases and then increases with the increase of slag content,and the cohesion is the largest when the slag content is 40%;In the direct shear test,the internal friction angle first increases and then decreases with the increase of slag content.When the slag content is 60%,the internal friction angle is the largest;It is obtained by triaxial test,the friction angle in the mixture increases with the increase of slag content,and the pure ultra-fine tailings sample is in a drum deformation state.With the increase of slag content,the failure mode of the mixture is shear failure gradually.2.Through the consolidation compression test,the variation law of the compressibility index of the mixture under different slag content and different load conditions is obtained,and the compression deformation mechanism is analyzed.With the increase of pressure,the pore ratio of pure ultra-fine tailings sample and mixture sample gradually decreases,the back end of the curve tends to be stable,and the pore ratio of mixture sample is greater than that of pure ultra-fine tailings sample;With the increase of bearing pressure,the compression coefficient of mixture decreases gradually;The addition of slag has a significant impact on the consolidation and compression capacity of the mixture.The compression coefficient of the mixture with 30%slag content is the lowest,followed by the mixture with 40% slag content.3.Through the permeability test,the variation law of the permeability coefficient of the mixture under the condition of different slag content is obtained,and its permeability mechanism is analyzed.The permeability coefficient of the mixture increases with the increase of slag content,which has a significant effect on the permeability of the mixture;4.Through the erosion test,the anti erosion law of the mixture under the condition of different slag content is obtained.The experimental results show that under the condition of different slag content,the anti-corrosion ability of the mixture under hydraulic action shows a nonlinear change law.With the increase of slag content,the erosion rate first decreases and then increases.The analysis shows that when the slag content is 40%,the erosion rate of the mixture is the lowest and the erosion resistance is the strongest;5.PFC meso simulation software is used to simulate the triaxial test process of the mixture.Combined with the stress-strain curve of the indoor test,the feasibility of this simulation is compared and verified;The shear process of the mixture is analyzed from the aspects of velocity vector diagram and displacement cloud diagram,and the micromechanical properties are analyzed.The increase of slag content,the particle movement and turnover direction become disordered,and the slag particles have a great impact on the development of the shear band of the mixture sample;The displacement nephogram of the mixture with 40% slag content changes.With the increase of axial strain,the slag particles begin to bear the main stress concentration area,and then spread to the surrounding tailings particles.Finally,the tailings particles and slag particles interact with each other. |
