露天矿复合边坡形成和变形失稳机理及关键因素优化研究

发布时间：2017-12-27 05:30

本文关键词：露天矿复合边坡形成和变形失稳机理及关键因素优化研究　出处：《中国矿业大学》2017年博士论文　论文类型：学位论文

【摘要】：本文对露天矿复合边坡的形成与变形机理进行了研究。边坡变形主要由岩体自重的竖向作用和堆载引起的附加荷载效应引起。研究认为,露天开采过程中开挖堆载引起的不平衡应力和位移是影响露天矿产资源安全开采的关键。根据复合边坡的形成特点,开采深度的不断增大和外排高度的协同增加造成复合边坡结构一直处于动态发展的过程。复合边坡的时效稳定性是影响露天矿安全生产的重要条件,因此,在采场开挖和外排堆载的工程计划基础上,结合所有的因素建立复合边坡角计算公式,根据排土场堆载高度建立附加荷载计算公式,并对排土场堆载之后产生的主动楔排在复合边坡深度上的分布规律进行了建模分析。从分析结果可以看出,复合边坡的整体角度由排土场高度、开采深度和外排位置这几个关键参数决定,并且在外排附加荷载产生的主动压力楔的滑移面逐渐偏转至边坡的边缘。通过分析和数值模拟,进一步建立了露天矿边坡荷载条件和几何参数对复合边坡应力场和安全系数的影响关系。数值模拟结果表明,增大边坡开挖深度和角度会导致复合边坡的地质应力场应力增加,外排堆载造成的边坡沉降量增大和外排安全范围减小。数值模拟分析的过程中突出了外排堆载位置对于边坡稳定性影响的敏感性,在采用极限平衡法进行二维分析的时候经常被忽略的外排堆载产生的附加应力。通过理论分析建立了复合边坡关键几何参数对安全系数的影响规律。这些关键参数间的相互作用和耦合效应对复合边坡的稳定性的影响极为显著,合理的参数选取可以提高边坡的安全系数,如果选择不当则会大大降低边坡的安全系数。从分析结果可以看出,单独增大边坡高度和角度所形成的复合边坡稳定性比同时增大边坡高度和角度时的稳定系数要高。采场边坡角和开挖深度与排土场堆载产生的耦合作用会进一步降低边坡安全系数,但合理的进行排土场位置选择会进一步提高边坡稳定性。造成这种现象的主要原因有降低排土场高度、增大排土场与采场的距离可以有效的降低排土场下部应力楔的大小,并且拉长滑移面的长度。此外,结果表明还表明,排土场堆载位置增大对于复合边坡安全系数的提升机理在于增长了潜在最危险滑动面和应力楔的面积。因此,排土场边坡的位置在复合边坡形成的过程中,对于提高其稳定性起着直观重要的作用。反复开挖和排弃导致软弱层内部应力重新分布,形成不均衡载荷,从而加剧了软弱层的变形和破坏。论文根据软弱层的力学模型和强度参数,通过数值模拟确定软弱层角和厚度对软岩边坡的影响,进而揭示软弱层对软岩边坡发育的影响规律。结果表明,软弱层倾角和厚度是影响边坡稳定性的关键因素。在弱层影响规律的基础上,对胜利露天煤矿的排土条件进行了综合分析,并在数值模拟的基础上,根据分析不同排土位置复合边坡的稳定系数,得出排土边缘距采场的临界安全距离。该研究对于了解复合边坡关键几何参数对露天矿边坡安全系数和应力场的影响具有指导作用。论文形成的科学高效的复合边坡参数设计理论和方法,对降低露天矿开采成本,提高生产安全性具有重要意义。
[Abstract]:In this paper, the formation and deformation mechanism of the composite slope in the open pit is studied. The deformation of the slope is mainly caused by the vertical action of the weight of the rock mass and the additional load effect caused by the loading of the pile. It is considered that the unbalance stress and displacement caused by the excavation in the process of open pit mining is the key to the safety mining of the mineral resources in the open pit. According to the characteristics of composite slope, the increasing of mining depth and the increase of discharge height cause the composite slope structure to be in a dynamic developing process. The time stability of composite slope are important factors that affect safety production of open-pit mine, therefore, in stope excavation and pile foundation project efflux load, combining all the factors in the establishment of composite slope angle formula, according to the dump height to establish additional load calculation formula, and the distribution of active wedge after the dump load in the depth of the composite slope were analyzed. From the analysis results, we can see that the overall angle of the composite slope is determined by several key parameters, such as the height of the dump, the depth of mining and the location of the discharge, and the slip surface of the active pressure wedge produced by the additional load is gradually deflected to the edge of the slope. Through the analysis and numerical simulation, the influence of the load conditions and geometric parameters on the stress field and safety factor of the composite slope is further established. The numerical simulation results show that increasing the excavation depth and angle of the slope will lead to the increase of the stress field of the composite stress field, and the increase of the slope settlement and the safety range of the discharge. In the process of numerical simulation, the sensitivity of efflux loading location to the stability of slope is highlighted, and the additional stress generated by outboard surcharge is often neglected when the limit equilibrium method is used for two-dimensional analysis. Through theoretical analysis, the influence of the key geometric parameters of the composite slope on the safety factor is established. The interaction and coupling effects of these key parameters on the stability of the composite slope are very significant. Reasonable parameter selection can improve the safety factor of the slope. If improper selection, it will greatly reduce the safety factor of the slope. It can be seen from the analysis results that the stability of composite slope increased by increasing the height and angle of the slope alone is higher than the increase of the slope height and angle. The coupling effect between the slope angle and the excavation depth and the dump load will further reduce the safety factor of the slope, but a reasonable selection of the location of the dump will further improve the slope stability. The main reason for this phenomenon is to reduce the height of dump and increase the distance between the dump and the stope, which can effectively reduce the size of the stress wedge below the dump and lengthen the length of the slip surface. In addition, the results also show that the increase of the loading location of the dump increases the area of the most dangerous sliding surface and the stress wedge for the safety factor of the composite slope. Therefore, the position of the slope of the dump field plays an important role in improving the stability of the compound slope in the process of the formation of the compound slope. Repeated excavation and discarding lead to the redistribution of stress in the weak layer, and the uneven load is formed, which aggravates the deformation and damage of the weak layer. According to the mechanical model and strength parameters of soft layer, the influence of soft layer angle and thickness on soft rock slope is determined by numerical simulation, and the influence rule of soft layer on the development of soft rock slope is revealed. The results show that the inclination and thickness of the weak layer are the key factors affecting the stability of the slope. Based on the influence law of the weak layer, the comprehensive analysis of the discharge conditions of Shengli open-pit coal mine is carried out. Based on the numerical simulation, the critical safety distance of the dump edge to the stope is obtained based on the analysis of the stability coefficient of the composite slope at different discharge locations. The study has a guiding role in understanding the impact of the key geometric parameters of the composite slope on the safety factor and the stress field of the open pit slope. The scientific and efficient design theory and method of composite slope parameters are of great significance to reduce the cost of open pit mining and improve the safety of production.
【学位授予单位】：中国矿业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TD824.7

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