【作者】 江文武；

【导师】 徐国元； 熊正明；

【作者基本信息】 中南大学 ， 岩土工程， 2009， 博士

【摘要】 众所周知,金川镍矿的矿岩稳定性差,地应力高,是国内外地下矿山开采难度最大的典型矿山之一。目前,金川二矿区1#矿体已下降至850m中段进行采矿活动,开采深度近1000m,正式步入深井开采矿山行列。时至今日,人们对二矿区1#矿体是适合采用两步骤采矿模式还是连续采矿模式进行开采的基本问题,仍然争论不休。无疑,进入深部采矿环境,矿山开采将面临更为复杂的技术难题。在系统调研专业文献的基础上,作者结合金川二矿区工程实际,采用现场调查、室内模拟、数值模拟与理论分析相结合的方法,对金川二矿区深部矿体的开采效应显现,以及相应危害性开采效应的潜在抑制技术,进行了深入系统地研究。主要工作如下:第一,采用三维非线性有限差分数值模拟方法,研究开采过程中地表变形问题,率先发现了采空区上方地表下沉与上升变形空间分布的时空演变过程与发展趋势的规律,为地表移动变形预测提供了理论依据,还给出了地表变形重点监测的区域范围。在发现地表下沉与上升变形现象的基础上,首次将岩体蠕变理论应用于地表变形规律方面的研究,定性地解释了二矿区地表移动变形由一个下沉区域演变为两个变形区域,即一个下沉变形区域和一个上升变形区域的内在机理;提出了采空区底板矿体“岩柱”破坏模型;分析了构造应力型矿山地表移动角变缓和移动范围扩大的原因,解释了二矿区14行线回风井发生倾斜的原因。还揭示了1000m临时水平矿柱,以及深部剩余相关分段矿体回采,对地表变形空间分布规律产生的影响;不同开采模式回采深部矿体产生的地表变形效应规律基本相同,但变形量的大小存在差别。所有这些,为今后二矿区地表工程设施布置位置的确定,提供了理论指导。第二,通过多中段开采条件下,临时水平矿柱抑制采空区变形效应的研究,揭示了临时水平矿柱从其形成、逐分段回采变薄直至最终消失全过程,在控制围岩地压活动方面所起作用的机制,以及临时矿柱应力与变形分布的演变规律。结论表明:临时水平矿柱形成之初,在控制上下围岩收敛变形方面,起到明显的作用,但在矿柱与围岩结合部位引起应力集中现象明显;回采水平矿柱,对采空区下盘围岩变形产生相对较大影响,但不至引起灾害性地压活动的产生。通过对两步骤采矿模式、连续采矿模式下临时水平矿柱的应力、位移等参数的动态分布变化,进行比较分析,发现:与连续采矿模式相比,两步骤采矿下盘区矿柱的存在,对临时水平矿柱的完整性、结构变形的平顺性起到一定程度的破坏性影响,水平矿柱的回采将面临更严峻的技术挑战。进一步地,基于多中段同时开采下水平矿柱的受力特征,采用突变理论的分析方法,建立了水平矿柱的尖点突变模型,导出了水平矿柱失稳的充要力学条件判据,得出了水平矿柱失稳概率小的结论,并提出了水平矿柱回采的工程技术措施。第三,对不同采矿模式(注:两步骤采矿模式、连续采矿模式)开采深部矿体产生的开采效应进行了系统地对比研究,得出二矿区深部矿体更适合采用连续采矿模式进行回采的重要结论,为生产与技术决策提供了重要支撑。采用三维数值模拟与理论分析结合的方法,研究了不同采矿模式下深部矿体回采,对下部待采矿体中的应力、位移及破坏区分布等产生的影响,对采空区上下盘围岩应力和收敛位移动态变化规律产生的影响,以及对上部原有采空区及围岩的受力与变形状态产生的影响;针对两步骤采矿模式特有的盘区矿柱问题,研究了盘区矿柱的稳定性及其回收技术难度情况,还对盘区矿柱回采引起的开采效应演变趋势,进行了探索。第四,应用力学模型对下向进路充填体结构(注:人工假顶结构)危险截面和危险点的分布状态进行了分析计算,发现了原有无筋充填体结构存在强度不足问题的内在原因,指出了提高充填体结构强度和稳定性新的技术途径。在下向进路充填体结构危险截面和危险点的分布状态分析计算发现问题的基础上,首次采用室内模拟实验,研究了不同充填材料、充填体内部布筋与否等因素,对下向进路充填体结构抗折力学性能产生的影响。结果表明:高浓度砂浆材料制成的充填体抗折力学性能明显比分级尾砂膏体材料制成的充填体差,充填体内部布置钢筋可明显提高充填体的抗折强度等重要结论。这为提高充填体强度和稳定性提供了新的技术途径。第五,率先提出了一种集成两步骤采矿模式、连续采矿模式之技术优势的新采矿模式—中央盘区有序滞后下降的整体连续开采模式,数值模拟结果初步证明,应用提出的新模式开采深部矿体,在维护区域稳定性与控制灾害性地压活动等方面,显现出了良好的应用前景,为今后深部矿体开采的地压活动控制提供了一条全新的研究方向。中央盘区有序滞后下降的整体连续开采模式的核心技术为:深部矿体中部设置一个有序滞后回采盘区,在该盘区中配合采用割帮回采技术使其与两翼盘区在回采时空衔接方面有效过度,实现深部矿体整体连续开采的技术目标。数值模拟结果显示:与两步骤开采模式和连续开采模式相比,新采矿模式改善采空区围岩变形的平顺性指标、控制采空区围岩收敛变形指标大小等方面,显现出了良好的技术优势。论文研究所获得的上述主要成果,进一步丰富了复杂条件下深井采矿技术的内涵,为金川公司二矿区深部矿体开采科学决策,以避免灾害性事故发生提供了重要的技术参考;对国内外高应力环境条件下深井采矿体开采过程地压控制方面的研究,具有重要的理论意义和工程应用价值。更多还原

【Abstract】 It is well-known that Jinchuan No.2 Mine is one of underground mines with the most difficult geological and mining conditions all over the world as its rockmass is extremely poor and it is subjected to complicated strata pressure. Nowadays, its mining operation has been descending to 850m level, the mining depth is about 1000 meters, and it might be regarded as a deep-level mine. As yet, it has been a controversial key topic whether continuous mining method or room and pillar mining method should be selected to extract NO.l orebody in the mine. Under the deep-level mining, the redistribution of ground pressure in surrounding rock and filling, induced by mining operation, inevitably became more complicated. Based on its mining engineering background and aiming at its concern about the main technical problems to be solved, the response of surrounding rock and filling to mining operation in deep level, and the relevant potential techniques for controlling dangerous response to mining, were studied systematically by means of field surveying, numerical modelling, model test, and theoretical analyse. The main research contents and conclusions in the dissertation are as follows:First of all, using three-dimensional finite difference code (FLAC3D), surface deformation, induced by underground mining operation in the mine, was simulated and studied. The space-time developing process and trend of distribution of subsidence and rise areas in the surface were found. The obtained conclusions were the basic of predicting the surface deformation from underground mining, and the main monitoring areas, reflecting the surface deformation, were circled.On the basis of finding the surface subsidence and rise phenomena, the surface deformation was further studied according to creep theory of rockmass with higher tectonic stress, the mechanism on the developing process of surface deformation, which experienced the evolution from one subsidence area at the beginning of mining to both of one subsidence area and a rise area as the mined-out range was expanded steadily, was pointed out qualitatively. The failure model of rock post in the mined-out range’s substructure was put forward. According to the analysis of cause that higher tectonic strata pressure made surface movement’s angle flat and made movement’s range wide, the inclined failure cause of ventilation shaft, located in NO.14 prospecting section, was explained.The effect of the recovery of temporary horizontal pillar at 1000m level and other sublevel ore remains in deep level on the surface deformation was demonstrated. It was found that the distribution pattern of surface deformation from different mining methods (continuous mining and room-and-pillar mining) was similar; but the magnitude of deformation was different.All of these conclusions above-mentioned could be used as guidance for determining the location of surface facilities and buildings in the mine.Secondly, by means of investigating into the effect of temporary horizontal pillar support on the structure deformation of mined-out range, during its full period from the pillar’s formation, thinning and disappearing finally as mining in sublevel downwards, the mechanism, on which temporary pillar support controlled redistribution of the ground pressure and convergence displacement in mined-out structure, was found, and the change in distribution of the pillar’s stress and deformation was obtained as the horizontal pillar was thinned and disappeared due mining in sublevel downwards.The results showed that at the beginning of pillar formation, it played important role in controlling the convergence between the hanging wall and footwall surrounding rock of mined-out range, but obvious stress concentration occurred in the conjunction of the pillar and surrounding rock. After recovering the pillar, the convergence deformation of the footwall increased obviously in comparison with the hang wall’s deformation, but it could not caused catastrophic ground pressure movement.By means of comparison analysis of change in stress and displacement of the pillar, respectively induced from room-and-pillar mining and continuous mining, it was found that in comparison with those of continuous mining, the integrality and smooth deformation trend of the temporary horizontal pillar were adversely influenced by the existence of panel vertical pillars (ribs) due to room-and-pillar mining, and the recovery of horizontal pillar would be more difficult in the future.Further, based on the stress state of temporary horizontal pillar under simultaneously mining in more than one levels, the cusp catastrophic model for predicting failure of the horizontal pillar was set up, the failure criterion of the pillar was deduced, and the little probability of the pillar failure was concluded as well. The engineering measures to be taken, aiming at safe recovery of the pillar, were given.Thirdly, the comparison investigation on the response of surrounding rock and filling to continuous mining and room-and-pillar mining, respectively, was made. The important conclusion that continuous mining was more suitable to be used to extract the deep-level orebody in the mine was obtained, and it was very helpful for the mine to make productive and technical decisions.Using FLAC3D modelling and theoretical analysis, the effect of different mining methods (continuous mining and room-and-pillar mining) on the stress, displacement and plastic zone in the bottom ore to be mine, on the stress and convergence displacement of hang wall and footwall surrounding rock, and on the stress and deformation state in upper mined-out range’s surrounding rock and filling, was systematically investigated.For the panel vertical pillars due to room-and-pillar mining, their stability were studied, and aiming at the second-step mining panel pillars their recovery techniques were discussed. Further, the effect of recovery of panel pillars on development of response of surrounding rock and filling was probed.Fourthly, the distribution of critical sections and points in underhand cut and cemented filling stoping structure (artificial roof) was calculated according to structural mechanics model, the intrinsic factors causing deficiency in bearing capacity of plain filling structure were found, and the technical measures against the deficiency in structure strength and stability were pointed out.The physical model experiments on the effect of the mortar types (high density tailings + cement, classified tailings + paste) and reinforcement or not on the flexural performance of filling structure were carried out. The results showed that the flexural performance of filling structure, made of classified tailings-and-paste mortar, was obviously better than that of high density tailings-and-cement mortar, and the flexural capacity of reinforced filling structure with low reinforcement ratio was enhanced obviously.Fifthly, a new integrated continuous mining model with central panel of sequentially delayed mining was put forward. The new continuous mining model absorbed the technical merits of both continuous mining and room-and-pillar mining in controlling response of surrounding rock and filling to mining operation. The preliminary results of numerical modelling showed that as the new continuous mining model was used to extracting deep-level ore in the mine, it had obviously technical advantages in controlling the adverse response of surrounding rock and filling to mining in deep level, and in preventing catastrophic ground pressure movement from happening. With the new continuous mining model, some new research interests in controlling ground pressure movement from deep-level mining were provided.The key of new continuous mining model mainly was that a central panel was firstly selected as sequentially delayed mining panel, the boundary cut-off mining and sequentially delayed mining were carried out in the central delayed panel as other panels of its two wings were continuously mined downwards, and thus the convergence deformation and stress state of surrounding rock and filling structure were smoothly improved. The results of numerical modelling showed that, in comparison with room-and-pillar mining and continuous mining, the new continuous mining model had comprehensive technical advantages in improvements in smooth trend of convergence deformation and redistribution of stress state of surrounding rock and filling, and in controlling the magnitude of convergence displacement. All of these improvements in the response of surrounding rock and filling to mining were good for the mine to prevent the catastrophic ground pressure movement in deep-level mining engineering.更多还原