采空区下近距离煤层综放面压架机理及其控制研究

发布时间：2018-06-12 07:34

本文选题：采空区下 + 近距离煤层　；参考：《太原理工大学》2015年硕士论文

【摘要】：我国井工开采以长壁为主，且顶板管理主要采用全部垮落法；对于煤层群在开采顺序上主要采用下行式。下行、长壁顶板全部垮落法开采近距离煤层群必然产生采空区下近距离煤层开采的问题。采空区下近距离煤层综放面由于煤厚加大，波及的顶板地层厚度也会加大；上层煤层采空区矸石静载作用和顶板结构失稳导致的应力应变重布，以及上下两层煤间稳定岩层厚度、强度等的变化都会导致初次来压、周期来压步距及其动载的变化，使得采场矿压显现更加复杂。因此，采空区下近距离煤层综放面的压架已经成为井工开采迫切需要解决的工程实际问题。目前采空区下近距离煤层综放面的压架的理论分析多集中于避开煤柱集中应力的问题。本文认为采空区下近距离煤层采动时，上覆采空区没有煤柱时，上覆垮落带裂隙带对下层煤的应力作用也会影响压架，同时可利用上覆采空区的积水对压架进行控制。因此，以山西西山斜沟煤矿13#煤为研究对象，通过理论分析、实验室试验以及数值模拟等研究方法，对13#煤层的压架机理、控制方法和控制效果进行了研究。主要研究成果为：（1）采空区下近距离煤层综放面开采时，断裂带可能直接贯通上覆采空区，采空区破碎岩体向下直接传递载荷，导致顶板岩层的静载荷比普通综采面大，顶板不易形成稳定的结构，老顶来压时易发生压架事故，导致工作面停滞，生产减慢。并在考虑上层煤层采后形成的垮落带裂隙带岩层重量的前提下，本文建立力学模型分析支架围岩关系，给出了采空区下近距离煤层综放面支架载荷分别与初次垮落步距和周期垮落步距的理论关系式以及垮落断面的抗拉强度计算公式。（2）利用上覆采空区积水对煤层顶板进行了弱化，根据顶板岩石的力学特性，从本工作面向上覆采空区钻孔，给出弱化工艺与参数，将上覆采空区积水引入钻孔，利用积水的自重压力以及物理化学性质进一步扩展裂缝，降低了岩石的物理强度，人为形成了一个弱面，操纵了顶板的垮落步距，操纵了压架，确保了下层煤工作面的正常回采。（3）对采空区下近距离煤层综放面的压架控制效果进行了数值模拟验证，分别建立积水弱化前后的数值计算模型，动态分析煤层采动中顶板结构及工作面的应力位移分布及破坏特征。从顶板岩层的破坏特征和应力应变分布特征来看，利用上覆采空区积水进行弱化控制后，，比弱化前支承压力峰值平均降低2000KN，顶煤下沉量峰值平均降低10mm~15mm，说明文章所提出的压架控制方法是可行的。
[Abstract]:The long wall is the main mining method in our country, and the roof management mainly adopts the whole caving method, and the coal seam group mainly adopts the downward type in the mining sequence. Downlink, long wall roof caving all mining short distance coal seam group will inevitably produce the problem of close distance coal seam mining under goaf. Due to the increase of coal thickness, the thickness of the affected roof strata will be increased under the goaf fully mechanized caving face. The static load action of gangue and the stress and strain redistribution caused by roof structure instability in the upper coal goaf, as well as the changes of the thickness and strength of the stable strata between the upper and lower coal layers will lead to the changes of the initial pressure, the periodic pressure step and the dynamic load. It makes the stope pressure appear more complicated. therefore The pressing frame of fully mechanized caving face in close distance coal seam under goaf has become an urgent engineering practical problem to be solved in well mining. At present, the theoretical analysis of pressure frame of fully mechanized caving face in close distance coal seam under goaf is mainly focused on the problem of avoiding the concentrated stress of coal pillar. In this paper, it is considered that the stress action of the fracture zone of the overlying caving zone on the lower coal will also affect the pressure frame when the coal seam is mined at close distance under the goaf and when there is no coal pillar in the overlying goaf, at the same time, the pressure frame can be controlled by using the water in the overlying goaf. Therefore, taking 13# coal of Xishan Jiaogou Coal Mine in Shanxi Province as the research object, through theoretical analysis, laboratory test and numerical simulation, the mechanism, control method and control effect of 13# coal seam are studied. The main research results are as follows: (1) when fully mechanized coal caving face is mined under goaf, the fault zone may directly pass through the overlying goaf, and the broken rock mass in goaf will directly transfer the load down, resulting in the static load of roof rock layer being larger than that of ordinary fully-mechanized coal face. The roof is not easy to form a stable structure. On the premise of considering the weight of rock layer in fracture zone of collapse zone formed after mining in upper coal seam, this paper establishes a mechanical model to analyze the relation of surrounding rock of support. This paper presents the theoretical relations between the support load of fully mechanized coal caving face under goaf and the initial collapse step distance and periodic collapse step distance, as well as the formula for calculating the tensile strength of caving section. (2) the roof of coal seam is weakened by water in overlying goaf. According to the mechanical characteristics of roof rock, the weakening process and parameters are given from this work, and the overlying goaf water is introduced into the borehole, and the cracks are further expanded by using the gravity pressure and physicochemical properties of the overlying goaf. The physical strength of the rock is reduced, a weak surface is formed artificially, the collapse step of the roof is manipulated, the pressure frame is manipulated, It ensures the normal mining of the lower coal face. (3) numerical simulation is carried out to verify the control effect of the pressure frame of the fully mechanized caving face in the near coal seam under the goaf, and the numerical calculation models before and after the weakening of the water are established, respectively. The stress and displacement distribution and failure characteristics of roof structure and working face in coal seam mining are analyzed dynamically. According to the failure characteristics and stress-strain distribution characteristics of roof strata, the overlying goaf water is used for weakening control, The peak value of abutment pressure is reduced by 2000KN and the peak value of top coal subsidence is reduced by 10mm / 15mm compared with that before weakening, which shows that the control method proposed in this paper is feasible.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD355;TD823.81

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