细粒铁尾矿的沉积特性与基本物理力学性质试验研究

Experimental study on sedimentary behavior and basic physical mechanical properties of fine iron tailings

尾矿的沉积与固结过程是形成强度和确定变形量的重要依据。为探求尾矿沉积过程中应力和孔隙水压力演变规律,揭示尾矿料的强度形成机理和变形特征,结合现场溜槽试验,对细粒铁尾矿的沉积坡度、以及沉积过程中的应力、孔隙水压力和有效应力的演变规律进行了监测。同时,采用十字板剪切仪确定了沉积完成后尾矿的剪切强度。在此基础上,对不同沉积断面尾矿料的颗粒级配和渗透特性进行了试验研究,分析尾矿沉积速率的演变机理。试验结果表明:颗粒研磨极其均匀的尾矿料的堆积形式和渗透特性与尾矿料的水力特性存在差别;受尾矿颗粒相对密实度较大、颗粒分布均匀等因素影响,增加尾矿料的可透水边界较施加外荷载,更能提升尾矿料中有效应力的形成速率;尾矿料表层硬化和封闭微孔隙引发了上层滞水入渗困难,应采用必要的引水导流措施降低高势能流体对筑坝稳定性的影响。

The process of deposition and consolidation of fragmented multiphase materials is the basis and prerequisite for studying their strength and deformation.To find out the evolution laws of stress and pore water pressure during the deposition of fine iron tailings and reveal the strength formation mechanism and deformation characteristics of tailings reservoir,the sedimentary slope of tailings,stress,pore water pressure and effective stress during the deposition process are monitored by field large-scale flume tests.Meanwhile,the shear strength of tailings after deposition is determined by the vane shear apparatus.On this basis,grain-size distribution and permeability characteristics of tailings from different sedimentary sections are tested to analyze the evolution mechanism of tailings sedimentation rate.The experimental results show that the accumulation form and permeability characteristics of tailings with extremely uniform particle grinding are different from those of soils.Due to the large proportion of tailings particles and uniform distribution of particles,increasing the permeable boundary of tailings can improve the formation rate of effective stress of tailings better than applying external loads.The surface hardening of tailings and the sealing of micro-pore trigger the formation of effective stress in tailings.It is difficult to infiltrate the stagnant water in the upper layer.Necessary diversion measures should be adopted to reduce the influences of high potential fluid on the stability of dam construction.