干湿循环作用下尾矿砂物理力学特性研究

发布时间：2017-12-27 09:40

本文关键词：干湿循环作用下尾矿砂物理力学特性研究　出处：《南华大学》2016年硕士论文　论文类型：学位论文

更多相关文章： 尾矿砂 干湿循环 力学特性 稳定性

【摘要】：由于降水入渗、水分蒸发、浸润线上升和下降等原因,使尾矿长期处于一种循环的吸湿-脱湿状态,在干湿循环过程中尾矿砂的物理力学特性变化机制,关系到整个尾矿坝的安全运行。因此,本文以湖南省内某尾矿坝为研究对象,采用现场取样、室内模拟试验的方式展开研究,首先对尾矿砂的基本物理力学参数进行测试,然后利用自制的分层取样试验装置模拟尾矿砂的干湿循环过程,对经历干湿循环过程的尾矿砂物理力学参数变化进行了详细研究分析,并采用强度折减法基本原理结合数值模拟软件ABAQUS,对经历干湿循环作用后尾矿坝的稳定性影响进行分析。本文的主要研究成果和结论有:(1)在干湿循环试验过程中,发现在不同的干湿循环次数下相同的含水率对应不同的基质吸力,尾矿砂的土-水特征曲线出现滞回效应,并且这种变化在前3次干湿循环过程中变化最大,随着干湿循环过程的继续,土-水特征曲线逐渐趋于稳定。(2)对尾矿砂在不同干湿循环次数时的土水特征曲线进行拟合,得到了干湿循环作用下尾矿砂土-水特征曲线的预测模型。(3)在干湿循环作用下,尾矿砂的抗剪强度随着干湿循环次数的增加逐渐降低,干湿循环4次以后尾矿砂的抗剪强度趋于稳定。强度的变化主要表现在强度参数内摩擦角和黏聚力的变化,随着干湿循环的进行尾矿砂的内摩擦角逐渐减小最终趋稳定,粘聚力也逐渐降低最终趋于稳定。内摩擦角随着干湿循环次数的最初衰减幅度要比粘聚力的衰减幅度大。(4)在干湿循环作用下,基质吸力为10kap尾矿砂的抗剪强度大于基质吸力为15kap时尾矿砂的抗剪强度,并且随着干湿循环次数的增加,在高应力状态下,基质吸力对尾矿砂抗剪强度的增大和减小的影响也会发生变化。(5)尾矿坝的安全系数随着干湿循环作用进行逐渐减低,在前3次干湿循环过程中尾矿坝的安全系数衰减速度较快,随后的衰减速度逐渐趋于稳定。在整个干湿循环过程中,尾矿坝的稳定性系数由2.05下降到1.70,整体下降幅度达到17.1%。同时也说明了干湿循环作用对尾矿坝的稳定性具有一定的影响。
[Abstract]:Because of the reasons of precipitation infiltration, water evaporation, rising and falling of seepage line and so on, tailings are in a state of cyclic moisture absorption and dehumidification for a long time. During the dry wet cycle, the mechanism of physical and mechanical characteristics of tailings is related to the safe operation of the whole tailings dam. Therefore, in this paper, a tailings dam in Hunan Province as the research object, studied by field sampling, indoor simulation test, first the basic physical and mechanical parameters of tailings were tested, and then use stratified sampling experiments simulating the tailings dry wet cycle process, the physical and mechanical parameters of tailings of wetting and drying cycles the detailed research and analysis, and the basic principle of the strength reduction method combined with numerical simulation software ABAQUS, the influence of tailings dam stability analysis through dry wet cycles. The main research results and conclusions of this paper are: (1) in the dry wet cycle test, found in water cycle corresponding to different under the same rate of different matric suction, water characteristic curve of tailings sand soil appeared hysteresis effect, and the change in the first 3 dry wet cycle process, the biggest change, with the continued cycle of dry and wet process, the soil water characteristic curve tends to be stable. (2) fitting the soil water characteristic curve of tailings under different cycles of wetting and drying cycles, the prediction model of soil water characteristic curve of tailings sand under dry wet cycling is obtained. (3) under the action of dry wet cycle, the shear strength of tailings decreases with the increase of dry and wet cycles. After 4 cycles of dry and wet cycling, the shear strength of tailings becomes stable. The change of strength is mainly manifested in the variation of internal friction angle and cohesive force of strength parameters. With the dry wet cycle, the internal friction angle of tailings decreases gradually, and finally becomes stable and cohesive force gradually decreases, and finally tends to be stable. The initial attenuation amplitude of the internal friction angle with the number of dry and wet cycles is larger than that of the cohesive force. (4) in the wet and dry cycle, matrix suction as the shear strength of 15kap is greater than the suction shear strength of 10kap tailings tailings, and with the increase of cycle times, in high stress state, the matrix suction effect of shear strength increase and decrease will change on the anti tail ore. (5) the safety factor of tailings dam decreases with the action of drying and wetting. In the first 3 dry and wet cycles, the safety factor of tailings dam decays faster, and then the attenuation speed gradually becomes stable. During the whole dry and wet cycle, the stability coefficient of the tailings dam decreased from 2.05 to 1.70, and the overall decline was 17.1%. It also shows that the effect of dry and wet circulation on the stability of tailings dam has a certain influence.
【学位授予单位】：南华大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TD926.4

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