多过程耦合效应下尾砂固结行为研究

The key to applying consolidated tailings discharge technology is whether the tailings particles can preferably solidify, without the occurrence of argillization and desertification problems. Under the coupled effects of chemical reaction progress (binder hydration), temperature variation process (changes of the tailings temperature and the environment temperature), and seepage process (fluid flow within the pore structures of consolidated tailings body), the consolidated tailings body will make varied responses, and perform different mechanical strength, permeability and durability. By taking consolidated tailings body as research object, and analyzing the interactions of these processes, the multi-process coupling mechanism of the consolidated tailings body will be revealed. On this basis, the corresponding coupled mathematical model will be developed. By taking advantage of the test equipment that will be made in this project, evolutions of the temperature, seepage discharge, porosity and uniaxial compressive strength will be investigated. Besides, the availability of the developed model will be validated against the experimental results. By means of numerical simulation, the tailings consolidation behavior and the stability of the consolidated tailings piles under the effects of different material proportions, environmental temperatures and rainfalls will be demonstrated. The research of this project is of certain theoretical significance to preparing economical, environmentally friendly, stable and durable consolidated tailings body, as well as to optimizing the stockpiling program of consolidated tailings body and setting up corresponding stability evaluation method.

应用尾砂固结排放技术的关键在于尾砂颗粒能否较好地固结起来而不发生泥化和沙化等问题。在化学反应过程（水泥等胶凝材料的水化反应）、温度变化过程（尾砂自身及环境温度改变）和渗流过程（尾砂固结体孔隙结构中的流体流动）的共同作用下，尾砂固结体将作出不同响应，表现出不同的力学强度、渗透性和耐久性。本课题以尾砂固结体为研究对象，通过分析上述各个过程之间的相互作用关系，揭示尾砂固结体的多过程耦合作用机理，并在此基础上建立相应的耦合数学模型；利用所制作的试验装置来探究尾砂固结体的温度、渗流量、孔隙率、单轴抗压强度等的变化规律，并验证上述耦合数学模型的有效性；通过数值模拟研究在不同的材料配比、环境温度、大气降雨等条件下，尾砂的固结行为以及尾砂固结堆体的稳定性。本课题的研究对于制备经济、环保、稳固及耐用的尾砂固结体具有一定的理论意义，对优化尾砂固结体的堆存方案及建立相应的稳定性评价方法具有一定的实际价值。

尾砂固结排放技术，是指在选厂排出的低浓度尾矿浆中添加少量的胶凝材料后将其浓缩脱水，形成尾砂固结体，然后堆存在地表塌陷坑或其他适当位置。尾砂固结体应具有一定的固结强度，遇水不会泥化，因此无需建设尾矿库进行堆存。通过不同配比条件下尾砂料浆流变性能、料浆固结初终凝时间、全尾砂固结体单轴抗压抗剪强度、孔隙结构参数、渗透性的全面实验，构建了表征固结改性作用下全尾砂固结体物性演化规律的数学模型，建立了基于实验数据的水化反应度数学模型和尾砂固结体孔隙率及渗透系数随水化反应度演化的数学模型，揭示了固结体微观结构发育机制；进行了化学场、渗流场耦合作用下尾砂固结排放中重金属浸出规律实验研究，揭示了尾砂排放初期的沉降泌水规律、长期堆置下固结体崩解规律，掌握了尾砂固结排放不同阶段重金属浸出规律和重金属固化效应，获得了表征浸出速度的的计算模型，阐明了固结体孔隙间溶质迁移的机制；构建了考虑尾砂固结排放不同阶段、不同外界环境及不同配比条件等多因素及多场耦合作用下尾砂固结排放的污染物浸出-迁移的耦合模型。基于静水压力理论和渗透压力理论，通过冻融循环试验研究了全尾砂固结体冻融损伤机理，构建了冻融循环作用下固结体的损伤模型；分析了全尾砂固结体冻融过程中温度场、渗流场、应力场的耦合关系，建立了温度场-渗流场-应力场的多场耦合模型。研究成果能够为具体工程条件下的尾砂固结排放堆体稳定性、耐久性的安全评价和重金属固结效果评价提供理论支撑。