Stability Analysis And Instability Process Of A Tailings Based On PFC2D

The tailing dam is one of the important structure to maintain the normal production of mine, and its stability is directly related to the security of its surrounding. So it is necessary to study its stability.At present, the main methods of analyzing the stability of the tailings dam are limit equilibrium method, finite element method and finite difference method. When limit equilibrium method is used to analyze the stability of the tailings dam, the solid is regarded as rigid body and the sliding surface should be assumed in advance.It is different from the actual situation. Though using finite element method and finite difference method can solve the above two problem, it is not appropriate that the solid is regarded as continuous elastic-plastic body. Then using these methods can not help observing the instability process of tailings dam. Based on the engineering background of a tailings dam, this paper regarded tailings as granular media and studied the stability and instability process of the tailings dam in the different working condition with considering the law of tailings’ distribution. The main research works are as follows:(1) With getting the tailings-samples of the tailing dam In different distances and doing the screening tests, it got the fitting equation of The average particle size and the distance. Then it analyzed the law of tailings’ distribution.(2) In order to analyze the relationship between the micro parameters of each material and the corresponding macro parameters, it used the orthogonal experimental to design nine groups of micro parameters for each material.Then it used PFC2D software to do the biaxial simulation test for each sample.According to the partial stress-strain curves, volume strain-axial strain curve and Moore-cullen curve of the simulation test, it calculated the corresponding macroscopic parameters. Finally it obtainthe order with the influence degree with range analysis.(3) Basedon theinfluence law between the micro parameters and the macro parameters, it chosed the micro parameters of each soil layer of the tailing dam model and made the macroscopic mechanical properties of the model be consistent with the actual materials.(4) Based on the law of tailings’distribution, it established PFC2D model of the tailings dam. Accroding to strength reduction method, it wrote the functions to get the safety factors in different conditions. And it compared them with the results of limit equilibrium method. The safety factors of PFC2D were bigger. becausethe micro parameters of PFC2D usually affect several macro parameters at the same time and the relatioship between the micro parameters and the the macro parameters is not linear.(5) It monitored the changes of strength in the model by setting monitoring circles. Then it analyzed thefailure development process of the tailings dam under different working conditions by observing the curves of stress and the displacement of the particles in the model. The sliding surfaceswere all circularunder different working conditions. The sliding surface was the deeppest under the the specialoperating condition. The sliding surface took the second place under the the flood water condition. The sliding surface was the shallowest under the the normal operating condition.It was consistent with the result by using limit equilibrium method.