余吾矿单轨吊巷道顶板稳定性机理及控制研究

发布时间：2018-09-06 12:48

【摘要】：煤炭对我国经济的发展有重要影响,我国是一个贫油少气富煤的国家,煤炭是我国的主体能源。我国95%的煤炭通过井工开采方式采出,而矿井采掘活动破坏了地下岩体原有的应力平衡状态,引起应力的重新分布,进而引发巷道冒顶、片帮、底板鼓起等一系列矿山压力现象的发生,影响工作面的正常生产。对于底鼓现象易发的巷道,矿车及机车运输方式不再适用,常常采用受巷道底板影响较小的单轨吊担任工作面的辅助运输。然而,单轨吊载荷作用下,巷道顶板承受高集中应力的作用,顶板的失稳方式及支护机理均发生较大改变,结合综放工作面的复杂应力环境及综放工作面巷道的空间位置布置方式对单轨吊巷道稳定性的影响作用,单轨吊巷道顶板稳定性的维持较为困难。本论文的研究依托于潞安矿业集团余吾煤矿S1203综放工作面,工作面地质构造简单,无顶板淋涌水现象,S1203工作面主采3#煤层:3#煤为黑色、块状构造、节理发育、参差状断口,主要由亮煤组成,并夹有镜煤暗煤条带,属光亮型煤。煤质为特低硫、低磷、中灰、热稳定性好、高发热量的优质动力煤,其煤种为贫煤类,煤层瓦斯含量低。为了解决工作面回采过程中单轨吊作用下回采巷道顶板稳定性的控制问题,本文进行了S1203工作面回风巷的顶板稳定性控制技术研究。针对以上研究内容,通过数值模拟及理论分析手段得出区段煤柱、巷道布置方式及单轨吊载荷对顶板稳定性的影响机理,并通过数值模拟研究综放开采采场侧向支承压力及偏应力第二不变量分布规律,对比分析支承压力及偏应力第二不变量得出单轨吊巷道区段保护煤柱的合理宽度;基于锚杆索预应力场的分布结构特征分析,提出巷道顶板支护的锚固复合深梁承载结构,并建立单轨吊作用下巷道顶板深梁稳定性力学模型,分析顶板锚固复合深梁承载结构的稳定性影响因素,通过分析不同参数下深梁的受剪情况得出单轨吊巷道顶板合理的支护参数,最终确定了单轨吊巷道的顶板支护方案,并进行了现场矿压观测。本论文的研究主要取得了以下结论:(1)在分析余吾煤矿S1202及S1203工作面实际生产地质条件及煤层赋存条件的基础上总结得出回风巷道顶板稳定性的主要影响因素为巷道的留设方式、巷道与煤层的空间位置关系、单轨吊载荷。(2)通过对综放开采下覆岩移动特征的分析,建立了综放开采条件下工作面老顶侧向端部整体结构模型,得出相邻工作面开采对单轨吊巷道稳定性的影响在于巷道围岩的完整程度与应力集中的相互矛盾。(3)通过数值模拟不同顶煤厚度条件下巷道围岩的应力场及位移场分布,得出顶煤厚度对巷道顶板稳定性的影响规律为:顶板岩层水平应力在顶板煤岩交界面处发生突变,水平应力增大,煤岩交界面稳定性差,随顶煤厚度的增加,巷道顶板附加载荷值增大,塑形区范围扩张,巷道变形量增大。(4)运用FLAC数值模拟软件模拟了工作面侧向支承压力及偏应力第二不变量随煤柱宽度的变化规律,不同煤柱宽度条件下,支承压力及偏应力第二不变量具有相同的变化规律。煤柱宽度较小,即采用沿空留巷时,煤柱内部处于低支承压力状态,应力向深部转移至巷道实体煤帮,巷道实体煤帮处于高集中应力状态,但煤柱及巷道实体煤帮受相邻工作面的采动影响处于大范围的塑形状态,巷道围岩的完整性差,稳定性低,自承能力差,不利于单轨吊作用下巷道顶板稳定性的维持;随煤柱宽度的增大,巷道及煤柱塑形区范围逐渐收缩,巷道受相邻工作面开采产生的应力叠加作用减弱,巷道围岩完整程度及两帮应力集中程度降低,维护难度降低。通过对S1202工作面侧向支承压力及偏应力第二不变量进行对比分析,得到偏应力第二不变量对煤柱宽度选择的指导作用,结合极限平衡理论下的煤柱宽度理论分析确定合理的煤柱宽度为30m。(5)通过分析巷道顶板的不同冒落形式得到单轨吊作用下巷道顶板的失稳机理,结合数值模拟得出单轨吊对巷道围岩位移场、应力场及塑形区分布的影响,单轨吊使得巷道顶板的应力及位移量增大,单轨吊载荷过大时,模拟单元网格发生变形,有可能发生局部岩体的拉断现象,因此,单轨吊作用下巷道顶板的维护重点为单轨吊悬吊区的浅部岩体。(6)通过对单轨吊作用下巷道顶板的稳定性判据分析,提出了余吾矿S1203综放工作面单轨吊回采巷巷道顶板总体的控制方向:应从维持顶板岩层自身完整入手,避免因单轨吊载荷作用及开采扰动导致的围岩内部原有裂隙的扩展及新裂隙的产生,使单轨吊悬吊锚杆的锚固点位于完整的稳定岩层中。(7)基于锚索预应力作用下的预应力场分布形态,建立多锚索作用下的数值模拟模型,模拟结果表明:多锚索作用下的预应力场近似为端部较窄,中部宽度较大的“鼓”形分布,辅以浅部锚杆的作用能够使预应力场呈近似的矩形状,并且通过调节锚索的间排距及预紧力等参数能够形成沿巷道轴向及切向均匀连续分布的预应力场,根据弹性力学的平面问题假设要求,提出预应力锚杆索作用下的顶板锚固复合深梁承载模型。(8)建立了单轨吊作用下巷道顶板锚固复合深梁承载结构简化力学模型,分别求得均布载荷、集中力作用下梁内的应力分布状态,通过应力叠加法得出多载荷耦合作用下深梁内部任一点的应力分量,基于最大剪应力强度准则得到深梁的稳定性求解公式。(9)通过对不同参数锚索作用下的预应力场分布形态分析,得出锚索参数对预应力场分布的影响规律,预应力场范围及应力值大小与锚索长度、间排距等锚索支护参数均为负相关关系,与锚索预紧力为正相关。(10)通过分析锚索预应力场及顶板锚固复合深梁的相关关系,得到锚索长度、间距及预紧力均为深梁稳定性的复合影响因素。运用MATLAB数值软件计算得出单轨吊及锚索支护阻力作用下不同结构尺寸深梁内部最大剪应力及预应力场分布情况,以最大剪应力近零应力区及锚索预应力扩散系数为衡量指标对深梁的稳定性进行量化分析,得到以下结论:单轨吊作用下,随单轨吊载荷的增加,深梁内部最大剪应力高应力区范围扩张,巷道浅部岩体的稳定性降低;锚索预紧力不仅影响深梁内部最大剪应力分布还影响预应力场的扩散情况,结合两者分析结果,高预紧力作用下深梁的稳定性增加;深梁内部最大剪应力近零应力区随锚索间距为先增大后减小的变化趋势,但锚索间距的增加导致预应力场扩散效果的减弱及预应力场沿巷道切向的差异程度升高。(11)结合现场实际情况,进行现场试验研究,通过现场矿压观测结果分析,最终确定了单轨吊作用下综放工作面回采巷道支护方案。单轨吊作用下的综放工作面回采巷道顶板采用密集长锚索支护,锚索长度为8300mm,间距900mm×900mm,预紧力200kN。在顶板打长锚索进行加固,使锚索锚固点处于未破坏的岩体内,借助锚索预应力的扩散作用使巷道表面软弱围岩及深部岩体形成复合锚固的深梁整体结构,辅以锚杆的作用对巷道浅部进行加固,有效抑制单轨吊载荷作用下的应力集中,控制巷道变形,提高其自身的稳定性。
[Abstract]:Coal has an important impact on the development of China's economy. China is a country rich in oil and gas. Coal is the main energy source in China. 95% of the coal in China is extracted by underground mining, and the mining activities destroy the original stress balance of underground rock mass, causing the redistribution of stress, and then lead to roof caving in roadways and side-slicing. A series of mine pressure phenomena, such as floor heave, affect the normal production of the working face. For the roadway which is prone to floor heave, the transportation mode of mine truck and locomotive is no longer applicable. Monorail crane, which is less affected by the floor of the roadway, is often used as the auxiliary transportation of the working face. However, under the monorail crane load, the roof of the roadway bears high concentration. It is difficult to maintain the stability of monorail lifting roadway roof in combination with the complex stress environment of fully-mechanized caving face and the influence of spatial layout of roadway on the stability of monorail lifting roadway. The S1203 fully mechanized caving face of Yuwu Coal Mine of Yicheng Group has simple geological structure and no roof water gushing phenomenon. The main mining face of S1203 is 3# coal seam: 3# coal is black, massive structure, joint development, uneven fracture surface, mainly composed of bright coal, with dark coal band of mirror coal, belonging to bright briquette. Coal quality is very low sulfur, low phosphorus, medium ash, good thermal stability, high. In order to solve the problem of controlling the roof stability of roadway under the action of monorail crane in the process of working face mining, this paper studies the roof stability control technology of S1203 working face air return roadway. The influence mechanism of section coal pillar, roadway layout and monorail crane load on roof stability is obtained by analysis method. The distribution law of the second invariant of lateral supporting pressure and deviatoric stress in fully mechanized caving mining stope is studied by numerical simulation. The second invariant of supporting pressure and deviatoric stress is compared and analyzed, and the combination of protective coal pillar in monorail crane roadway section is obtained. Based on the analysis of structural characteristics of the prestressing field of anchor cables, the load-bearing structure of anchored composite deep beams in roadway roof support is put forward, and the mechanical model of the stability of roof deep beams under the action of monorail crane is established, the influencing factors of the stability of the load-bearing structure of roof anchored composite deep beams are analyzed, and the shear behavior of deep beams under different parameters is analyzed. In this paper, the main conclusions are as follows: (1) On the basis of analyzing the actual production geological conditions and coal seam occurrence conditions of S1202 and S1203 working faces in Yuwu Coal Mine, the paper summarizes and draws a conclusion. The main influencing factors of the stability of the roof of the return air roadway are the way of retaining the roadway, the space position relationship between the roadway and the coal seam, and the monorail lifting load. (2) Through the analysis of the movement characteristics of the overlying rock under the fully mechanized caving mining, the whole structure model of the lateral end of the main roof under the fully mechanized caving mining condition is established, and the monorail lifting roadway is obtained from the adjacent working face. The influence of roadway stability lies in the contradiction between the integrity of roadway surrounding rock and stress concentration. (3) Through numerical simulation of stress field and displacement field distribution of roadway surrounding rock under different roof thickness, the influence law of roof thickness on roadway roof stability is obtained as follows: horizontal stress of roof rock bursts at the interface of roof coal and rock. With the increase of the thickness of the top coal, the additional load value of the roof increases, the range of the plastic zone expands, and the deformation of the roadway increases. (4) The variation of the second invariant of the lateral supporting pressure and the deviatoric stress with the width of the coal pillar and the width of the coal pillar are simulated by FLAC numerical simulation software. The second invariant of supporting pressure and deviatoric stress has the same change rule under the condition of the condition that the width of coal pillar is small, that is, when the roadway is retained along the goaf, the coal pillar is in the state of low supporting pressure, and the stress is transferred to the roadway solid coal seam to the depth, and the roadway solid coal seam is in the state of high concentrated stress, but the coal pillar and roadway solid seam are subjected to the adjacent working face. The influence of mining is in a large range of plastic shape, the integrity of surrounding rock is poor, the stability is low, and the self-supporting capacity is poor, which is not conducive to the maintenance of the stability of the roof of the roadway under the action of monorail crane; with the increase of the width of coal pillar, the range of the roadway and the plastic zone of coal pillar gradually shrinks, the stress superposition effect of the roadway caused by mining in the adjacent working face is weakened, and the roadway is not conducive By comparing and analyzing the second invariant of lateral supporting pressure and deviatoric stress of S1202 working face, the guiding role of the second invariant of deviatoric stress on the selection of coal pillar width is obtained, and the reasonable coal pillar width is determined by combining the theoretical analysis of coal pillar width under the limit equilibrium theory. The column width is 30m. (5) The instability mechanism of the roadway roof under the action of monorail crane is obtained by analyzing the different caving forms of the roadway roof. Combined with the numerical simulation, the influence of monorail crane on the displacement field, stress field and plastic zone distribution of the roadway surrounding rock is obtained. The roof of roadway under monorail suspension is mainly maintained in shallow rock mass of monorail suspension area. (6) Based on the analysis of stability criterion of roadway roof under monorail suspension, the overall roof of monorail suspension mining roadway in S1203 fully mechanized caving face of Yuwu Coal Mine is put forward. Control direction: Maintaining the integrity of roof rock strata, avoiding the expansion of original cracks and the generation of new cracks in surrounding rock caused by monorail crane loading and mining disturbance, so that the anchorage point of monorail suspension anchor rod is located in a complete stable rock strata. (7) Based on the distribution pattern of prestressing field under the action of anchor cable prestressing, the construction of monorail suspension anchor rod is carried out. The numerical simulation results show that the prestressing field under the action of multi-anchor cables is approximately a narrow end and a large "drum" shape distribution in the middle of the cables, supplemented by the action of shallow anchors, can make the prestressing field approximate rectangular shape, and can form an edge by adjusting the parameters such as the distance between the cables and the pre-tightening force. The prestressing field distributed uniformly and continuously in the axial and tangential directions of the roadway is presented. According to the assumption of plane problem in elasticity, the bearing model of roof anchored composite deep beam under the action of prestressed anchor cable is put forward. (8) The simplified mechanical model of roof anchored composite deep beam bearing structure under the action of Monorail crane is established, and the uniform load and concentrated force are obtained respectively. Stress distribution in the beam under action is analyzed. Stress components at any point in the deep beam under multi-load coupling are obtained by stress superposition method. Stability formulas of the deep beam are obtained based on the maximum shear stress strength criterion. (9) By analyzing the distribution of prestressing field under different parameters of anchor cable, the prestressing force is calculated. The influence law of field distribution shows that the range of prestressing field and stress value are negatively correlated with the length of anchor cable and the distance between rows, and are positively correlated with the prestressing force of anchor cable. (10) By analyzing the correlation between the prestressing field of anchor cable and the composite deep beam anchored by roof, the length of anchor cable, the distance between anchor cable and the prestressing force are all stable of deep beam. The distribution of maximum shear stress and prestress field in deep beams with different structural sizes under the action of resistance of monorail crane and anchor rope is calculated by MATLAB. The stability of deep beams is quantitatively analyzed with the near zero stress zone of maximum shear stress and the diffusion coefficient of prestress of anchor rope as the evaluation index. The results are as follows. Conclusion: With the increase of monorail crane load, the range of maximum shear stress and high stress zone in deep beam expands, and the stability of rock mass in shallow roadway decreases. The pre-tension of anchor cable not only affects the distribution of maximum shear stress in deep beam, but also affects the diffusion of prestress field. The maximum shear stress near zero stress zone in deep beam increases firstly and then decreases with the anchor cable spacing, but the increase of anchor cable spacing leads to the weakening of prestressing field diffusion effect and the increase of prestressing field tangential difference along the roadway. (11) Combining with the actual situation in the field, the field test is carried out, and the field rock pressure observation is carried out. The roof of fully mechanized top-coal caving face under the action of monorail crane is supported by dense long anchor cable, the length of anchor cable is 8300 mm, the spacing is 900 mm 65 In rock mass, with the help of the diffusion of prestressing force of anchor cable, the weak surrounding rock and deep rock mass on the roadway surface form a composite anchored deep beam integral structure, and the shallow part of the roadway is reinforced by the action of anchor rod, which can effectively restrain the stress concentration under the load of monorail crane, control the deformation of the roadway and improve its own stability.
【学位授予单位】：中国矿业大学(北京)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TD327.2

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