基于PFC2D某尾矿库稳定性分析及失稳过程研究

发布时间：2018-05-24 22:33

本文选题：尾矿坝 + 粒径分布规律　；参考：《昆明理工大学》2015年硕士论文

【摘要】：尾矿库是维持矿山正常生产的重要构筑物,其稳定性直接关系到其周边的安全性,因此,对其稳定性进行研究是非常有必要的。目前,分析尾矿库坝体稳定性的方法主要有极限平衡法、有限元法和有限差分法。极限平衡法分析坝体稳定性时将岩土体作为刚体来研究,且需提前假设滑动面,与实际情况不符。有限元法和有限差分法虽然克服了以上两个问题,但其将尾砂作为连续的弹塑性体来研究,也与实际存在一定的差异。并且,这几种方法都不能直观地观察尾矿坝的失稳过程。本文以某尾矿库为工程背景,将尾砂模拟为散体材料,在考虑库内尾砂分布规律的前提下,采用颗粒流离散元软件PFC2D对该尾矿库不同工况下的稳定性及失稳过程进行了研究。本文完成了以下几个方面的内容：(1)在距尾矿坝放矿口不同距离进行尾砂取样,然后在通过筛分试验分析了各组尾砂样品的平均粒径,最后,将平均粒径与距离之间的关系进行拟合,分析尾矿库内尾砂的沉积规律。(2)针对PFC2D中无黏结材料、接触黏结材料及平行黏结材料,利用正交试验设计方法分别设计了9组微观参数,然后利用PFC2D软件对每组试样进行了双轴模拟试验,通过模拟试验得出的偏应力-应变曲线、体积应变-轴向应变曲线及摩尔-库伦曲线计算出其对应的宏观参数,最后通过对宏观参数进行极差分析得出了不同材料微观参数对宏观参数影响程度的排序。(3)以微观参数对宏观参数的影响规律为基础,对尾矿坝模型中的基岩、初期坝及尾砂微观参数进行了标定,使模型中材料的宏观力学特性与实际一致。(4)根据尾矿库内尾砂沉积规律建立了尾矿坝PFC2D模型,然后,以强度折减法的基本思想为基础,编写了强度折减函数得出了采用PFC2D软件模拟时正常水位、洪水位和地震洪水位时尾矿库的安全系数,并与极限平衡法的结果进行了对比分析。采用PFC2D软件得出的安全系数是偏大的,这主要是由于PFC2D软件所采用的微观参数会同时对多个宏观参数产生影响,且微观参数与宏观参数之间并不是线性关系。(5)在尾矿坝模型中设立了监测圆,对强度折减条件下监测圆内部的应力变化情况进行了监测,通过观察应力变化曲线及模型中颗粒的位移情况,分析了不同工况下尾矿坝失稳破坏的形态及其发展过程。尾矿坝在三种工况下的破坏滑动面都为圆弧形,特殊运行条件下的圆弧滑面最深,洪水位运行条件下的圆弧滑面次之,正常水位运行条件下的圆弧面最浅,与极限平衡法得出的结果一致。
[Abstract]:Tailing reservoir is an important structure to maintain the normal production of mines, and its stability is directly related to its peripheral security. Therefore, it is very necessary to study its stability. At present, the main methods to analyze the stability of tailing dam are limit equilibrium method, finite element method and finite difference method. When the limit equilibrium method is used to analyze the stability of the dam, the rock and soil are considered as rigid bodies, and the sliding surface should be assumed in advance, which is not in accordance with the actual situation. Although the finite element method and the finite difference method overcome the above two problems, the tailings are studied as a continuous elastoplastic body, which is different from the actual situation. Moreover, none of these methods can directly observe the instability process of tailings dam. In this paper, a tailings reservoir is used as engineering background, tailings are simulated as bulk materials, and the stability and instability process of the tailings reservoir under different working conditions are studied by using the particle flow discrete element software PFC2D under the premise of considering the distribution law of tailing sand in the reservoir. In this paper, the following aspects are completed: 1) sampling tailings at different distances from the tailings dam caving opening, and then analyzing the average particle size of each group of tailings by sieving test. The relationship between average particle size and distance is fitted, and the deposition rule of tailings in tailing reservoir is analyzed. Nine groups of microscopic parameters were designed by orthogonal design method, and then biaxial simulation tests were carried out on each group of samples by PFC2D software. The deflection stress-strain curves obtained from the simulation tests were obtained. The corresponding macroscopic parameters are calculated by the volume strain-axial strain curve and the Mole-Coulomb curve. Finally, through the range analysis of the macro parameters, the order of the influence degree of the micro parameters of different materials on the macro parameters is obtained. Based on the law of the influence of the micro parameters on the macro parameters, the bedrock in the tailings dam model is studied. The microcosmic parameters of the initial dam and the tailings are calibrated, and the macroscopic mechanical properties of the materials in the model are consistent with the actual conditions. (4) the PFC2D model of the tailings dam is established according to the law of tailings deposition in the tailings reservoir, and then based on the basic idea of the strength reduction method. The strength reduction function is compiled to obtain the safety factors of the tailings reservoir when the normal water level, flood water level and earthquake flood water level are simulated by PFC2D software, and the results are compared with those of the limit equilibrium method. The safety factor obtained by using PFC2D software is on the high side, which is mainly due to the influence of microcosmic parameters used by PFC2D software on many macro parameters at the same time. Moreover, there is no linear relationship between microscopic parameters and macroscopic parameters. (5) Monitoring circle is established in the tailings dam model, and the stress change inside the monitoring circle is monitored under the condition of strength reduction. By observing the stress change curve and the displacement of the particles in the model, the failure pattern and development process of tailings dam under different working conditions are analyzed. The failure slip surface of tailings dam under three working conditions is arc shape, the arc slip surface is the deepest under the special operation condition, the circular arc slip surface under the flood water level is the second, and the arc surface is the shallowest under the normal water level operation condition. The results are consistent with those obtained by the limit equilibrium method.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD926.4

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