透镜体对尾矿坝地震动力特性影响研究

发布时间：2018-03-31 15:14

本文选题：尾矿坝　切入点：透镜体　出处：《重庆科技学院》2017年硕士论文

【摘要】：尾矿库是一个具有高势能的人造泥石流的重大危险源。在近几十年里,世界范围内因地震造成尾矿坝溃坝灾害的事故不胜枚举,给下游人民群众的生命财产安全和周边环境造成重大损失。我国有95%以上的尾矿库采用上游法方式筑坝,但在上游法筑坝过程中极易在堆积坝内产生不同数量和尺寸的透镜体,严重影响着坝体在地震工况下的稳定性。本文采用室内力学测试、模型试验和数值计算相结合的研究方法对含不同数量和尺寸透镜体尾矿坝在地震工况下的稳定性进行深入研究,得到以下结论:(1)通过室内实验测试得出尾矿力学特性:对于不含透镜体尾矿料,随着粒径减小内摩擦角随之减小,黏聚力逐渐增大;对于含不同数量透镜体的尾矿料,黏聚力随着透镜体数量的增加而变大,尾中砂和尾细砂随着透镜体数量的增加内摩擦角逐渐减小;通过对尾矿砂微观测试和分析可知,尾矿砂粒径越大,孔径越大,孔隙率也随之增大,从而也增大了尾矿的渗透能力。(2)通过对尾矿坝地震工况渗流特性计算可知:不含透镜体尾矿坝浸润线呈一条平滑的曲线;而含透镜体时,坝体浸润线有所升高且呈不规则形状;分析透镜体位置对浸润线影响可知,透镜体水平分布在坝体中部和下部时,浸润线明显较分布在上部时要高,这主要是由于坝体上部透镜体位于浸润线以上,对坝体渗流产生影响较小所致。随着透镜体数量不断增加,地震工况作用下坝体浸润线在堆积坝中下游段出现与坡面相交的现象,坝体水位溢出。(3)通过对地震工况下尾矿坝稳定性计算可知:未考虑透镜体时,坝体处于安全状态;当含透镜体时,在正常工况和地震工况下,坝体稳定性随透镜体分布位置由上至下依次减小,主要是由于下部透镜体多分布在坝体滑弧面附近,降低坝体强度所致;随着透镜体数量的增加和尺寸的增大,坝体安全系数也逐渐降低。(4)通过小型尾矿库地震模型试验可知,在地震工况下,尾矿坝坝顶最先出现裂纹,随着地震作用时间的持续,裂纹不断扩大并逐渐向坝体中下游部位发展,在整个地震过程中,坝体中下游部位破坏程度较明显。
[Abstract]:Tailing reservoir is a major hazard source of man-made debris flow with high potential energy. In recent decades, there have been numerous accidents caused by earthquakes in the world. More than 95% of the tailings reservoirs in China use upstream method to build dams, but in the process of upstream dam construction, it is easy to produce different numbers and sizes of lens bodies in the dam. The stability of dam body under earthquake condition is seriously affected. The stability of tailings dams with different numbers and sizes under seismic conditions is studied by combining model test and numerical calculation. The following conclusions are obtained: the mechanical properties of tailings are obtained by laboratory tests: for the tailings without lens, the cohesion force increases with the decrease of the internal friction angle of the particle size, and for the tailings with different numbers of lens bodies, The cohesion force increases with the increase of the number of lens bodies, and the internal friction angles of the sand in the tail and the fine sand decrease with the increase of the number of the lens bodies, and the microcosmic test and analysis of the tailings show that the larger the particle size of the tailings, the larger the pore size. Porosity also increases, thus increasing the permeability of tailings. (2) through the calculation of seepage characteristics of tailings dam under earthquake conditions, it can be concluded that the wetting line of tailings dam without lens is a smooth curve, and the seepage line of tailings dam without lens is a smooth curve. When the horizontal distribution of the lens is in the middle and the lower part of the dam, the infiltrating line is obviously higher than that in the upper part. This is mainly due to the fact that the upper lens of the dam is located above the infiltration line, which has little effect on the seepage of the dam. Under the action of earthquake condition, the seepage line of dam body intersects with the slope in the middle and lower reaches of the stacking dam, and the dam water level overflow is calculated by calculating the stability of the tailings dam under the earthquake condition: when the lens is not considered, the dam body is in a safe state; Under normal and seismic conditions, the stability of the dam decreases with the distribution of the lens from top to bottom, mainly due to the distribution of the lower lens near the slippery arc surface of the dam, which reduces the strength of the dam. With the increase of the number and size of the lens, the safety factor of the dam decreases gradually. (4) through the seismic model test of the small tailings reservoir, it can be seen that the crack first appears at the top of the tailings dam under the earthquake condition, and with the duration of the earthquake action, The crack expands and develops gradually to the middle and lower reaches of the dam body. During the whole earthquake, the damage degree of the middle and lower reaches of the dam body is obvious.
【学位授予单位】：重庆科技学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD926.4;P315.9

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