矿山胶结充填体损伤过程声发射特性研究与应用

发布时间：2018-08-28 14:40

【摘要】：目前,金属矿床开采向深部发展,伴随着矿体赋存条件变复杂、地压急剧增大、软弱岩层增多、固体废料堆积等问题的出现,导致矿体回采和地压管理的难度不断增加,并伴随着一系列的安全生产隐患,与此同时,矿山企业对矿石回采品位的要求不断提高,因此,连续开采已经成为地下金属矿山的发展方向。与其他采矿方法相比,充填采矿法以其可以有效提高矿石回采率、减少矿石贫化率,方便地压管理等诸多优点得到了广泛应用。但是,随着开采深度的不断增加,充填体在井下所受的力学环境变得越来越复杂,一旦发生破坏或失稳,将对周边矿房的安全回采造成严重的威胁。为使充填采矿法发挥其最大效益,实现安全有效的生产,做好充填体的损伤特性的研究并能对充填体的破坏提出准确及时的预判是势在必行的,也是刻不容缓的。本文根据胶结充填体承受载荷的受力特征,进行循环载荷作用下胶结充填体损伤特性和声发射特性试验及相关理论研究,旨在反映工程实际力学路径,利用声发射揭示充填体损伤破坏机理,得出尾砂胶结充填体配比和损伤参量之间的关系。并利用不同的声发射参数分形维数来表征尾砂胶结充填体内部损伤,为矿山胶结充填体承载过程分析及破坏失稳预测提供基础研究依据。本文选用玉溪矿业大红山铜矿分级尾砂作为试验材料,设计了不同配比的分级尾砂胶结充填体循环加卸载试验和声发射试验,试验研究结果表明:(1)尾砂胶结充填体试件在相同应力水平循环加卸载时,总应变ε和塑性应变εp随着循环次数的增加而减小,弹性应变εe随着循环次数的增加而增大;当在逐级递增的应力水平下循环加卸载时,总应变￡,塑性应变εp和弹性应变εe和随着循环次数的增加而增大。弹性模量E1随着循环周次的增加而减小,而加载变形模量E2则不然,当试件在相同应力水平循环加卸载时,充填体试件的加载变形模量E2随着循环次数的增加而减小,当应力水平提高时,加载变形模量E2陡然增大;(2)充填体试件加载阶段即为弹性应变能储存阶段,储存的能量在卸载时缓慢释放出来,而当储存的弹性应变能大于临界值时,储存的弹性应变能就会不受充填体的束缚而突然爆发出来,导致充填体失稳破坏;而不可逆耗散能会随着循环次数的增加呈现出"缓慢→加速→急速"增长的态势,不可逆耗散能的增加会降低充填体的力学性质,所以充填体的破坏是能量的释放和耗散的共同作用的结果,能量耗散使充填体发生劣化,力学性能降低,而能量释放造成了充填体的整体失稳破坏;(3)本文经过大量试验,对谢和平等人提出的损伤演化方程进行改良,提出了基于损伤能量释放率的充填体损伤演化方程,能较好的反映充填体损伤行为,并和充填体的配比有着良好的关联性;(4)从声发射振铃计数和能量计数可以看出,充填体同样具有Kaiser效应;(5)充填体的破坏是一个降维的过程,分形维数的急剧减小预示着充填体大规模的失稳破坏即将来临,因此,可将充填体声发射振铃计数分形维数,能量分形维数和振幅分形维数的急剧减小作为充填体即将发生失稳破坏的判据。且三种分形维数效果最好的是振幅分形维数,利用声发射振幅分形维数研究充填体内部损伤效果更佳。(6)提出了尾砂胶结充填体在循环加卸载条件下的声发射累积能量和损伤参量以及配合比之间的定量关系,最终得到了基于声发射累积能量的充填体损伤演化预测模型本文研究成果对探究尾砂胶结充填体的损伤破坏机理有着重要的理论意义,且对矿山充填体失稳破坏的预测预判的研究有着较高的应用价值和指导意义。
[Abstract]:At present, the mining of metal deposits is developing to the deep part, accompanied by the complicated occurrence conditions of ore bodies, the sharp increase of ground pressure, the increase of weak rock strata, the accumulation of solid waste and other problems, resulting in the increasing difficulty of ore body mining and pressure management, and accompanied by a series of hidden dangers of safe production, at the same time, mining enterprises on the ore mining grade. Compared with other mining methods, filling mining method has been widely used because it can effectively improve ore recovery rate, reduce ore dilution rate, and is convenient for ground pressure management. The mechanical environment underground is becoming more and more complicated, once it is destroyed or destabilized, it will pose a serious threat to the safe mining of the surrounding chambers. In order to make the filling mining method play its maximum benefit, realize safe and effective production, do a good job in the study of the damage characteristics of the filling body and provide accurate and timely prediction of the damage of the filling body. According to the mechanical characteristics of cemented backfill under load, the damage characteristics and acoustic emission characteristics of cemented backfill under cyclic loading are studied in this paper. The purpose is to reflect the actual mechanical path of engineering, reveal the damage mechanism of backfill by acoustic emission, and obtain the tailings glue. The fractal dimension of different acoustic emission parameters is used to characterize the internal damage of cemented tailings filling, which provides the basic research basis for the analysis of loading process of cemented backfill and the prediction of failure instability. The results of cyclic loading and unloading tests and acoustic emission tests of cemented tailings backfills with different proportions show that: (1) The total strain and plastic strain epsilon P decrease with the increase of cyclic loading and unloading times, while the elastic strain epsilon increases with the increase of cyclic loading and unloading times. The elastic modulus E1 decreases with the increase of cyclic cycles, while the loading and unloading modulus E2 does not. When the specimen is loaded and unloaded at the same stress level, the total strain, plastic strain epsilon and elastic strain epsilon increase with the increase of cyclic times. The loading deformation modulus E2 decreases with the increase of cyclic times, and increases sharply with the increase of stress level. (2) The loading stage of the filling specimen is the storage stage of elastic strain energy, which releases slowly during unloading, and when the stored elastic strain energy is greater than the critical value, the stored elastic strain energy will increase sharply. The irreversible dissipation energy will increase slowly accelerate rapidly with the increase of the number of cycles, and the increase of irreversible dissipation energy will reduce the mechanical properties of the filling body, so the failure of the filling body is a combination of energy release and dissipation. As a result, energy dissipation deteriorates the filling body and reduces its mechanical properties, while energy release causes the overall instability of the filling body. (3) Based on a large number of tests, the damage evolution equation proposed by Xie Ping et al. is improved, and the damage evolution equation based on the damage energy release rate is proposed, which can better reverse the damage. The damage behavior of filling body is related to the ratio of filling body. (4) The Kaiser effect of filling body can be seen from the acoustic emission ringing counts and energy counts. (5) The failure of filling body is a process of dimension reduction, and the sharp decrease of fractal dimension indicates that the large-scale instability failure of filling body is imminent. The fractal dimension of acoustic emission ringing counting, the sharp decrease of energy fractal dimension and amplitude fractal dimension can be used as the criterion of instability failure of filling body. Quantitative relationship among acoustic emission cumulative energy, damage parameters and mixing ratio of sand-cemented filling under cyclic loading and unloading conditions is obtained. Finally, a damage evolution prediction model based on acoustic emission cumulative energy is obtained. The research results of this paper have important theoretical significance for exploring the damage mechanism of tailings-cemented filling. It is of high application value and guiding significance to predict and predict the instability failure of mine backfill.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD853.34

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