综放工作面采空区渗流场域及渗透系数研究

发布时间：2018-03-23 10:40

本文选题：采空区　切入点：应力三区　出处：《辽宁工程技术大学》2015年博士论文

【摘要】：工作面漏风是采空区内煤自燃需氧来源的唯一途径,且煤矿井下采空区空间构成复杂多变,其渗流场域参数的改变,直接影响到渗流流场的改变,从而影响到采空区内煤自燃三带分布及其它采空区灾害的形成和防治.因此,对采空区内渗流场域及其特性的研究显得尤为重要.综放工作面形成的采空区具有空间大、遗煤多的显著特征,其渗流场域及渗流特性在不同采放比条件下具有一定的规律性,该类问题的分析是综放工作面采空区渗流规律研究的基础,也是综放工作面采空区灾害防治技术的理论支撑.本文结合实际矿井情况,采取理论分析、实验研究和数值模拟相结合的研究方法,展开了以下研究：采空区渗流场域的形成特征及影响因素；将煤壁支撑影响区域内的冒落煤岩体视为自由堆积体多孔介质,利用自制模型,对自由堆积体均质、非均质多孔介质进行了一维渗流实验研究,探究渗流速度、渗流压力梯度与介质粒径大小的关系,渗流状态转变的渗流速度阈值；建立采空区三维渗流模型,进行了工作面阻力分布对工作面两端压差、采空区内渗流压力的影响实验；基于采空区应力分布确定综放工作面采空区渗流场域大小的方法,利用离散元程序UDEC建立了综放工作面在采放比为1：1、1：2、1：3时的数值模型,分析了采空区走向渗流场域、倾向渗流场域随采放比的变化规律；利用CFD软件Fluent分析了综放工作面采空区在不同采放比下的渗流规律、工作面阻力分布对工作面两端压差及采空区渗流的影响,最后,通过现场实测数据的分析,验证了实验规律和数值模拟规律的正确性.研究结果表明：在相同渗透速度变化范围内,随着构成多孔介质“骨架”颗粒粒径的增加,渗透的压力梯度降低,渗流状态逐步由以粘性力为主的线性渗流向以惯性力为主的非线性渗流转变,且转变的渗流速度阈值逐步减小；非均质多孔介质中的渗透系数和渗流状态转变的渗流速度大小主要取决于其小粒径颗粒所占的比例；在相同地质条件下,随着综放工作面采放比的增加,采空区渗流场域在走向上减小,高度增加；采空区内渗流速度场分布具有较弱的对称性,进风隅角和回风隅角在相同速度区间内,回风侧渗流范围大于进风侧渗流范围,走向上,过渡渗流(非线性渗流)区域均出现减小的趋势,倾向上,过渡渗流(非线性渗流)区域增加；工作面阻力主要分布于进风端、回风端和工作面中部时,工作面两端压差依次减小,且当工作面阻力分布于工作面中部时,采空区中部渗透深度增加,工作面阻力分布于进、回风端时,采空区渗流出现明显的非对称分布.
[Abstract]:The air leakage is the only way to the oxygen source of coal spontaneous combustion in goaf, and the space of goaf in coal mine is complex and changeable. The change of seepage field parameters directly affects the change of seepage flow field. Thus, the distribution of coal spontaneous combustion and the formation and prevention of other goaf disasters in goaf are affected. Therefore, it is very important to study the seepage field and its characteristics in goaf. The goaf formed in fully mechanized caving face has a large space. There are some remarkable characteristics of residual coal, its seepage field and seepage characteristic have certain regularity under different mining and caving ratio conditions. The analysis of this kind of problem is the foundation of the study of seepage law in goaf of fully mechanized caving face. It is also the theoretical support of the technology of disaster prevention and control in goaf of fully mechanized caving face. This paper combines the actual mine situation with theoretical analysis, experimental research and numerical simulation. The following studies are carried out: the forming characteristics and influencing factors of seepage field in goaf, the caving rock mass in the area affected by coal wall support is regarded as the porous medium of free accumulation body, and the free deposit body is homogenized by self-made model. In this paper, the experimental study of one-dimensional seepage in heterogeneous porous media is carried out to explore the relationship between seepage velocity, pressure gradient and particle size of medium, the threshold of seepage velocity for seepage state transition, and the three-dimensional seepage model in goaf. The influence of the resistance distribution on the pressure difference between the two ends of the face and the seepage pressure in the goaf is carried out, and the method of determining the field size of the seepage field in the goaf of the fully mechanized caving face based on the stress distribution in the goaf is presented. The numerical model of fully mechanized caving face with mining caving ratio of 1: 1 / 1: 1: 1: 3 is established by using discrete element program UDEC, and the variation law of trend seepage field and inclined seepage field with the ratio of mining to caving is analyzed. CFD software Fluent is used to analyze the seepage law of goaf in fully mechanized caving face under different mining caving ratio, and the influence of face resistance distribution on the pressure difference at both ends of the face and seepage flow in goaf. Finally, the field measured data are analyzed. The experimental and numerical simulation results show that the pressure gradient of the porous media decreases with the increase of the particle size of the "skeleton" particles in the same permeation velocity range. The seepage state gradually changes from linear seepage with viscous force to nonlinear seepage with inertia force, and the threshold of seepage velocity gradually decreases. The permeability coefficient in heterogeneous porous media and the seepage velocity of seepage state transition mainly depend on the proportion of small particle size, and under the same geological conditions, with the increase of mining caving ratio in fully mechanized caving face, The distribution of seepage velocity field in goaf has weaker symmetry, and the flow range of return wind side is larger than that of inlet wind side in the same velocity range. The trend of transition seepage (nonlinear seepage) is decreasing, the tendency of transition seepage (nonlinear seepage) is increasing, and the face resistance is mainly distributed in the air inlet end, the return air end and the middle of the face. The pressure difference between the two ends of the face decreases in turn, and when the face resistance is distributed in the middle of the face, the penetration depth in the middle of the goaf increases, the resistance of the face is distributed in the entry, and when the return air ends, the seepage in the goaf appears obvious asymmetric distribution.
【学位授予单位】：辽宁工程技术大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TD752.2

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