高浓度尾矿筑坝加速固结沉积措施研究

发布时间：2018-07-20 20:12

【摘要】：使用尾矿筑坝是矿山生产中资源再利用的一种有效方式。尾矿固结沉积效果直接关系到尾矿库的建设,包括了对干滩形成条件、子坝修筑以及坝体稳定性的影响。因此,研究如何加速尾矿固结沉积速度,提高干滩强度,对尾矿库工程意义重大。本文以南京梅山高浓度尾矿筑坝工程为例,采用现场试验、室内土工试验、数值计算和工程实际结合的方法,对高浓度尾矿压滤筑坝以及加速尾矿沉积固结措施作了初步研究。本文所做的主要工作和取得的研究成果如下所列：(1)通过试验对高浓度尾矿筑坝的可行性进行了研究,得出此尾矿压滤之后可以用于干堆筑坝的结论。在高浓度放矿条件下,对干滩50m处尾矿的固结进行了相关计算,结果显示此放矿模式下尾矿沉积固结不完全,修筑三级子坝静力稳定性不满足工程要求。(2)在高浓度放矿尾矿固结不完全的情况下,考虑到土袋特有的工程特性,通过抛土袋挤淤的方法加固干滩,并经过计算得出了挤淤断面的形状和挤入的深度。在此基础之上,对坝体的静力稳定性进行了校核,结果表明满足稳定性要求,验证了挤淤加固干滩的可行性。(3)现场做了尾矿高浓度排放流槽试验和库区尾矿稀释排放试验。试验过程中保证尾矿流量一致,一段时间后,对流槽和库区相同位置的尾矿进行了采样分析。通过对颗粒组成进行分析,发现尾矿稀释之后低浓度排放的颗粒分选效果比高浓度直接排放好,50m干滩内粗颗粒(粒径大于0.075mm)的含量更高。运用Geo-studio软件对高浓度放矿和低浓度排放50m处尾矿的固结和坝体的稳定性进行了对比计算,结果表明：低浓度排放库区的浸润线埋深更深,尾矿固结基本完成,坝体相对安全。为尾矿库高浓度输送低浓度排放工艺的研究提供了有力的依据。(4)高浓度尾矿稀释排放之后,库区尾矿砂分布区域增大,饱和松砂在受到地震或其他振动时易发生液化。通过振动进行预液化处理,液化之后土颗粒重组,变得密实,为后期进一步加固和筑坝做准备。利用土工动三轴试验,选取不同的振动幅值、振动频率、固结比,对尾矿砂的液化特性进行了研究。结果表明：振动幅值越大,土体液化所需的时间越短；随着振动频率的升高,孔压的上升速率增大,土体抗液化强度降低,越容易发生液化；增大固结比,土体抗液化强度提高。这为现场预液化和夯实试验研究提供了借鉴。
[Abstract]:Using tailings to build dams is an effective way to reuse resources in mine production. The effect of tailings consolidation and deposition is directly related to the construction of tailings reservoir, including the influence on the formation condition of dry beach, the construction of sub-dam and the stability of dam body. Therefore, it is of great significance to study how to accelerate the tailing consolidation and deposition speed and improve the dry beach strength. Taking the high concentration tailings dam construction project of Meishan in Nanjing as an example, using the methods of field test, laboratory geotechnical test, numerical calculation and engineering practice, this paper makes a preliminary study on the high concentration tailings pressure filter dam construction and the measures to accelerate the consolidation of tailings deposition. The main work and research results obtained in this paper are listed as follows: (1) the feasibility of high concentration tailings dam construction is studied through experiments, and the conclusion that the tailings can be used for dam construction in dry pile after pressure filtration is obtained. Under the condition of high concentration drawing, the consolidation of tailings at 50 m in Gantan is calculated. The results show that the consolidation of tailings is not complete under this drawing model. The static stability of the third grade sub-dam is not satisfied with the engineering requirements. (2) under the condition of incomplete consolidation of high concentration tailings, considering the special engineering characteristics of soil bag, the dry beach is strengthened by throwing soil bag and squeezing and silting. The shape and depth of extrusion section are calculated. On this basis, the static stability of the dam body is checked, and the results show that the stability requirement is satisfied, and the feasibility of strengthening dry beach by squeezing silt is verified. (3) High concentration discharge trough test of tailings and dilution discharge test of tailings in the reservoir area are done in the field. In the process of experiment, the tailings flow rate is consistent. After a period of time, the tailings in the same position of flow trough and reservoir area are sampled and analyzed. Through the analysis of particle composition, it is found that the concentration of coarse particles (diameter larger than 0.075mm) in 50 m dry beach is higher than that in high concentration direct discharge of coarse particles (larger than 0.075mm) after dilution of tailings. By using Geo-studio software, the consolidation of tailings and the stability of dam body at high concentration drawing and 50 m low concentration discharge are compared and calculated. The results show that the infiltration line of low concentration discharge reservoir area is deeper, the tailings consolidation is basically completed, and the dam body is relatively safe. It provides a powerful basis for the study of high concentration and low concentration tailings discharge technology. (4) after dilution and discharge of high concentration tailings, the distribution area of tailings increases, and saturated loose sand is easily liquefied when it is subjected to earthquake or other vibration. Through vibration pre-liquefaction treatment, soil particles are reorganized and become dense after liquefaction, which makes preparation for further reinforcement and dam construction in the later stage. The liquefaction characteristics of tailings have been studied by using geo-dynamic triaxial tests with different vibration amplitudes, vibration frequencies and consolidation ratios. The results show that the larger the amplitude of vibration, the shorter the time required for soil liquefaction, with the increase of vibration frequency, the increase rate of pore pressure, the decrease of soil anti-liquefaction strength, and the increase of consolidation ratio. The liquefaction strength of soil is improved. This provides a reference for field pre-liquefaction and tamping test research.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD926.4

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