降雨因素对尾矿库溃坝的影响及安全预警技术研究

发布时间：2018-01-21 22:35

本文关键词： 降雨尾矿库溃坝弹性波　出处：《北京科技大学》2017年博士论文　论文类型：学位论文

【摘要】：尾矿库是矿山主要控制工程和重大危险源。生产实践表明:由于尾矿库坝体构成介质的松散特性,致使其在外界扰动下,如降雨、地震、液化等条件下易引发尾矿库溃坝事故,尤其是在连续降雨情况下极易引发尾矿库溃坝。因此,开展降雨因素对尾矿库溃坝的影响及安全预警技术研究,对提高尾矿库降雨条件下安全运行,实现对尾矿库溃坝的预测、预报,保障下游居民的生命财产安全,具有重要意义。本文对江西省自1960年起的14起尾矿库事故尤其6起溃坝事故发生时的降雨情况进行了详细统计,得出降雨条件下尾矿库溃坝的模式,结合尾矿库实例,开展了物理模拟试验与数值模拟试验,分析了尾矿坝在渐进溃坝和瞬时溃坝两种模式下的演化规律,以及瞬时溃坝时水流的流动特性。而后,开展基于波导杆采集声学信号的尾矿库溃坝的优化试验,研究了不同波导杆杆径与碎石粒径条件下,溃坝破坏过程中的声学特征,提出了基于声学监测的尾矿库溃坝的预测方法。在此基础上,建立了弹性波在波导杆中频散方程,计算了衰减频散曲线,分析弹性波在波导杆中传播的衰减规律,进而对波导杆杆径与碎石粒径进行优化选择。最后,通过对某尾矿库坝体进行了水平、竖向位移与弹性波监测,对坝体稳定性进行了科学分析。本文主要的研究内容包括:(1)通过分析江西省6起尾矿库溃坝事故时的降雨特征,得出溃坝事故均发生在汛期内,在事故发生时,尾矿库所在地均有3天以上连续性降水,且溃坝事故的当日,当地均有超过50mm的大暴雨。(2)尾矿库溃坝的溃口破坏程度取决于溢流对坝体的冲刷侵蚀作用。在渐进溃坝条件下,溃坝过程表现出明显的陡坎式渐进破坏模式;在瞬时溃坝条件下,坝体沟底底坡与溃坝水流方向相逆,右侧坝段溃口水流在淤砂和折转水流共同作用下形成坝下游逆时针旋流;左侧坝段溃口水流形成左右两个旋流。(3)在坝体临近溃坝时弹性波能量分形维数表现为增大而后快速减小的趋势,弹性波主频位于15kHz～77.8 kHz,该特征可作为尾矿库坝体溃坝的前兆特征。(4)弹性波在波导杆中的衰减随着波导杆杆径的增大而减小;当采用10-16mm粒径的碎石对波导杆包裹时,此时弹性波的主频在0～0.25MHz范围内出现次数最多。因此,在工程实践中,宜选用大杆径的波导杆与10-16mm粒径碎石的组合。(5)通过收集溃坝事故发生前不同时段的降雨数据,运用统计分析方法,建立了基于降雨数据的二元logistic回归模型,得到当日降雨量与累计降雨量的定量关系,针对某尾矿库安全度无法判定,对其进行了水平、竖向位移与弹性波监测,通过分析监测结果,认为该尾矿坝总体处于稳定状态。
[Abstract]:The tailing reservoir is the main control project and the major hazard source in the mine. The production practice shows that because of the loose characteristic of the dam body, the tailing reservoir is disturbed by the outside environment, such as rainfall and earthquake. It is easy to cause tailing dam break accident under the condition of liquefaction, especially in the case of continuous rainfall. Therefore, the influence of rainfall factors on tailing dam break and safety early warning technology are studied. It can improve the safe operation of tailing reservoir under rainfall condition, realize the prediction and forecast of tailing dam break, and ensure the safety of life and property of downstream residents. This paper makes detailed statistics on the rainfall situation of 14 tailing dam accidents, especially 6 dam-break accidents in Jiangxi Province since 1960, and obtains the model of tailing dam break under rainfall conditions. Combined with an example of tailings reservoir, physical and numerical simulation tests are carried out, and the evolution of tailings dam under two modes of progressive dam break and instantaneous dam break is analyzed, as well as the flow characteristics of water flow during transient dam break. The optimal test of tailing dam break based on acoustic signal acquisition by waveguide rod is carried out. The acoustic characteristics of dam break under different diameter of waveguide rod and gravel diameter are studied. The prediction method of tailing dam failure based on acoustic monitoring is proposed. Based on this, the dispersion equation of elastic wave in waveguide rod is established, and the attenuation dispersion curve is calculated. The attenuation law of elastic wave propagation in waveguide rod is analyzed, and then the diameter of waveguide rod and gravel diameter are optimized. Finally, the horizontal, vertical displacement and elastic wave monitoring of a tailing dam body are carried out. The stability of dam body is analyzed scientifically. The main research contents in this paper include: 1) by analyzing the rainfall characteristics of 6 tailing dam break accidents in Jiangxi Province, it is concluded that dam break accidents all occur in flood season. At the time of the accident, there are more than 3 days of continuous precipitation in the tailing area, and the day of dam break accident. There are more than 50 mm heavy rain in the local area.) the failure degree of dam break of tailing reservoir depends on the scour erosion effect of overflow on the dam body, under the condition of progressive dam break. The dam-break process shows obvious steep-ridge-type progressive failure mode. Under the condition of instantaneous dam break, the bottom slope of the dam body is opposite to the direction of the dam break flow, and the flow at the right end of the dam section is counterclockwise swirling under the combined action of silt and converted flow. When the dam body is near the dam break, the fractal dimension of elastic wave energy increases and then decreases rapidly. The main frequency of elastic wave is located at 15kHz ~ 77.8 kHz, which can be used as a precursor feature of dam collapse in tailing dam.) the attenuation of elastic wave in the waveguide rod decreases with the increase of the diameter of the waveguide rod. When the waveguide rod is wrapped with gravel of 10-16mm diameter, the main frequency of elastic wave appears most frequently in the range of 0 ~ 0.25MHz. Therefore, it is in engineering practice. The combination of large-diameter waveguide rod and 10-16mm diameter gravel should be used to collect the rainfall data of different periods before the dam break accident, and the statistical analysis method is used. A binary logistic regression model based on rainfall data was established, and the quantitative relationship between the daily rainfall and the accumulated rainfall was obtained. The vertical displacement and elastic wave monitoring results show that the tailings dam is in a stable state.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TD926.4

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