井采扰动对露天矿边坡稳定性的影响研究

发布时间：2018-10-09 17:05

【摘要】：露天开采煤矿过程中,形成的高大边坡下部积压着大量的煤炭资源,为提高煤炭的回收率,提高矿山的经济效益,许多矿山企业采取井工的方式回采煤炭资源。然而,边坡下部井采对边坡稳定性影响极大且机理复杂,与一般的边坡滑移和单一井工引起的地表沉陷不同,井采边坡的稳定性研究需综合考虑边坡滑移、边坡岩移,以及地表沉陷等因素的影响。因此,本文综合运用边坡工程学和开采沉陷学理论开展了井采边坡的岩移机制分析,同时,选取井东煤业广场西北帮边坡为工程实例,借助数值模拟分析了该边坡下部井采前后的稳定性状况,归纳其失稳破坏规律。[1]针对井东煤业广场西北帮边坡,结合边坡地质资料和工程背景,分析了边坡工程的滑坡现状;从边坡自身因素、自然因素和人工因素三个方面分别分析了不同因素对露天矿边坡稳定性的影响,其中自然因素和人工因素是外因,岩体自身因素是内因,内外因不是独立起作用的,是共同作用的。[2]综合运用边坡工程学和开采沉陷学的理论知识,研究下部井采对边坡稳定性的影响机理。机理如下:井工开采对边坡稳定性的影响,主要体现在采空区和爆破振动对边坡稳定性的影响。爆破振动对边坡的作用表现为促进裂缝的开展,使裂缝变宽、变密,影响地下井采的整个过程。采空区的存在,首先使覆岩应力释放,岩层应力重分布,由此引起覆岩冒落破坏,引起上部岩层的变形移动,随着井工工作面的推进,采空区增大,井采影响范围也变大,作用在地表表现为地表沉陷,作用在坡表表现为指向采空区的移动和指向临空侧的移动。另外,岩土层的变形破坏使边坡体内部产生裂缝,使岩土体强度降低,在降雨、地震等外因作用下,容易引起边坡滑移。[3]借助功能强大、操作简便的大型有限元软件ABAQUS开展了井采前后边坡稳定性研究。比较分析几种经典的本构模型,考虑到岩土体复杂的应力应变关系,选取Mohr-Coulomb本构模型。详细阐述了强度折减法的原理,并分析了学者们提出的三种判别准则,它们有各自的适用性,考虑到边坡工程的实际情况,决定采用以塑性区贯通为特征,以特征区位移拐点为依据求安全系数。[4]实地考察研究区边坡,通过现场取样和室内试验的方法,确定岩土体的物理力学参数。运用数值模拟的方法,研究边坡在井采前的稳定性,得到边坡在开采前的安全系数为2.71,处于稳定状态。然后,模拟井采后边坡的稳定性,得到井采后边坡岩土体变形场和应力场,并用井采对边坡稳定性影响机理解释了变化的原因,井采后,边坡安全系数大大降低。[5]运用ABAQUS软件,研究了不同位置的采空区对边坡稳定性的影响。通过不同工况之间的比较,得出如下结论:采空区与边坡坡面的相对位置对边坡稳定性有很大影响;采空区距离坡表很近时,坡体内部靠近采空区端部产生剪应力集中区,坡体同时有指向临空侧的水平移动和向下方采空区移动的变形趋势;随着采空区与坡面距离的增加,坡表受采空区影响减小,边坡竖向位移以指向采空区的沉陷为主;采空区距离边坡坡面越近,安全系数越小。
[Abstract]:In the process of open-pit coal mining, a large amount of coal resources are accumulated in the lower part of the high side slope formed, so as to improve the recovery rate of the coal and improve the economic benefit of the mine. However, the slope stability of the lower well of the side slope has great influence on the stability of the slope and the mechanism is complicated, which is different from the general slope slip and the surface subsidence caused by single well engineering. The stability of the well mining slope needs to comprehensively consider the influence of the slope slip, the slope rock movement and the surface subsidence. Therefore, the paper comprehensively uses the theory of slope engineering and mining subsidence to carry out the analysis of the rock movement mechanism of the well mining slope. At the same time, the slope of the northwest side slope of the East Coal Industry Square is selected as an engineering example, and the stability condition before and after the mining in the lower part of the slope is analyzed by means of numerical simulation. In this paper, the damage rule of its instability is summarized.[1] According to the geological data of slope and the background of engineering, the present situation of slope engineering is analyzed, and the influence of different factors on stability of open-pit slope is analyzed from three aspects: side slope self-factor, natural factor and artificial factor. The natural factors and artificial factors are the internal causes, and the internal and external factors play a common role in the internal and external factors.[2] Based on the theory knowledge of slope engineering and mining subsidence, the influence mechanism of lower well mining on slope stability is studied. The mechanism is as follows: the influence of the mining on the stability of the slope is mainly reflected in the influence of the goaf and blasting vibration on the stability of the slope. The effect of blasting vibration on the slope is to promote the development of cracks, so that the crack becomes wider and dense and affects the whole process of underground well production. The existence of mined-out area firstly causes the stress release of overburden rock and redistribution of stress redistribution of rock stratum, thus causing the rock overburden to fall and damage, which causes deformation movement of upper rock stratum. With the advancing of the working face of well, the goaf increases, the influence range of well mining is also changed, and the action plays a role in surface subsidence on the surface. The action is shown in the slope table as the movement directed to the gob and the movement directed toward the blank side. In addition, the deformation of the rock soil layer breaks the crack inside the slope body, so that the strength of the rock-soil body is reduced, and the slope slip can be easily caused under the action of rainfall, earthquake and the like.[3] By means of powerful and easy-to-operate large-scale finite element software ABAQUS, the stability of slope stability before and after well mining is carried out. Based on the comparison and analysis of several classical models, Mohr-Coulomb model is selected taking into account the complex stress-strain relation of rock and soil body. In this paper, the principle of strength reduction and subtraction is described in detail, and the three kinds of discrimination criteria proposed by scholars are analyzed. They have their applicability. Considering the practical situation of slope engineering, it is decided to adopt the characteristics of the plastic zone to pass through, and the factor of safety is calculated based on the inflection point of the feature area.[4] The physical and mechanical parameters of the rock and soil body are determined by field sampling and indoor test method. By means of numerical simulation, the stability of the slope before the mining is studied, and the safety coefficient of the slope before mining is 2.71, which is in a stable state. Then, the stability of the slope after the well mining is simulated, and the deformation field and stress field of the rock and soil body after the well mining are obtained, and the cause of the change is explained by the influence mechanism of the well production on the slope stability, and the safety factor of the slope is greatly reduced after the well production.[5] Using ABAQUS software, the effect of gob on slope stability in different locations was studied. Through the comparison between different working conditions, it is concluded that the relative position of the goaf and the slope slope has great influence on the stability of the slope; when the distance slope of the mined-out area is close, the shear stress concentration zone is generated near the end part of the goaf, Along with the increase of the distance between the goaf and the slope surface, the slope table is affected by the mined-out area, the vertical displacement of the slope is dominated by the subsidence of the mined-out area, the closer the slope surface of the side slope of the mined-out area is, the less the safety factor is.
【学位授予单位】：青岛理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD824.7

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