大采高综采采场支架-围岩稳定控制机理研究

Stability control mechanism of support-surrounding rocks at fully mechanized mining face with great cutting height

大采高综采技术是厚煤层安全高效高采出率开采的重要发展方向,随着采高向6.0～7.0 m发展,采场煤壁片帮、冒顶、压架、支架失稳发生率高,且控制困难,已成为制约该技术推广应用的瓶颈。针对上述难题及采场片帮、冒顶、压架和支架失稳间互馈联动性强的特征,以6.0 m左右大采高综采采场为研究对象,采用理论分析、数值模拟、物理模拟、仿真试验及现场实测等手段,对大采高综采采场支架-围岩稳定控制机理进行了系统研究,得到了如下研究成果:(1)研究了大采高综采采场覆岩结构特征与支架合理承载。根据直接顶厚硬岩层对覆岩垮落具有重要影响的特点,提出了大采高综采采场直接顶关键层的概念与确定方法,分析了其对覆岩垮落特征和超前支承压力分布的影响规律;依据有无直接顶关键层对直接顶分类并计算支架工作阻力:Ⅰ类无直接顶关键层条件按4～8倍采高岩柱质量计算支架工作阻力,Ⅱ类有直接顶关键层条件支架工作阻力计算需考虑直接顶关键层厚度、强度与层位的影响。(2)研究了大采高综采支架的稳定控制机理。分析了基于失稳临界角的支架下滑、倾倒与尾部受扭的力学特征;采用敏感性分析方法对大采高综采采场支架稳定性进行控制,增强了支架稳定控制的针对性和有效性;提出了端部底煤留设的新方式,实现了端部底煤回收与提高端部倾斜支架组稳定性的统一。(3)研究了高帮煤壁片帮机理与防治技术。煤壁片帮是一个由微观裂隙发育到宏观"楔形"滑动体失稳的过程,采用损伤力学理论,通过建立煤壁损伤变量与裂隙发育程度的联系,揭示了煤壁片帮的微观机理;基于高帮煤壁片帮特征实测,建立煤壁"楔形"滑动体稳定性分析的三维力学模型,揭示了煤壁片帮的宏观机理,分析了影响其稳定性的主要因素,提出了高帮煤壁片帮防治技术。(4)将煤壁稳定控制纳入采场支架-围岩控制体系中,提出了支架等效支护阻力和等效护帮力的概念与计算方法,揭示了大采高综采采场"煤壁-顶板-底板"空间围岩运动与支架工作状态之间的相互作用机理。(5)采用系统动力学方法研究采场支架-围岩相互作用关系,初步建立了大采高综采采场"W-R-F-S"系统的SD模型,通过Vensim软件的仿真模拟,定量描述了不同控制策略条件下"W-R-F-S"系统的稳定性。(6)上述研究成果在淮北矿业集团许疃煤矿7219工作面及阳煤集团寺家庄煤矿15104工作面得到应用和验证,并现场实测了典型大采高综采采场的来压规律、煤壁片帮特征及支架-围岩相互作用关系。

Fully mechanized mining technology with great cutting height is an important development trend with safety,high efficiency and high recovery rate,but it is hard to control the difficulties of rib spalling,roof falling,high support pressurizing and failure rate with the cutting height development to 6.0~7.0 m which have become the prominent problems for the application of this technology.In order to face these challenges and consider the strong crossfeed connection of rib spalling,roof falling,support pressurizing and failure,this paper focused on 6.0 m fully mechanized high seam mining stope,the theoretical analysis,numerical simulation,physical modeling,simulation experiments,simulation experiments and field measurement are used in this study and the mechanism of support-rock stability control in the high seam mining stope is systemically researched,the following results are obtained：（1） The overlying rock structure and the reasonable loading of support in high seam mining is researched.According to the important influence of direct overlying thick and hard roof rocks on the collapsing of under rock,the concept and determination method of key direct overlying layer are proposed,the overlying strata collapsing features and the distribution of advanced supporting pressure are analyzed.Based on whether the direct roof having the key direct overlying layer or not,the direct support resistance is calculated,typeⅠwith no key direct overlying layer condition the support resistance is calculated by 4 to 8 times weight of cutting rock while the type Ⅱ with key direct overlying condition the support resistance is calculated by considering the thickness,intensity and of layer horizon features of key direct overlying layer.（2） The stability control mechanism in high seam mining is researched.Based on the research of critical instability angle,the mechanical characteristics of the support declining,dumping and tail twisting are analyzed,the sensitivity analysis method is used to control the support stability in high seam mining stope,the pertinence and validity of stability control are enhanced,the coal leaving method in the bottom is proposed,the combination of bottom coal recovery and stability improvement of the bottom declining support group is achieved.（3） The mechanism and prevention techniques of rib spalling of high coal wall are researched.Rib spalling is the instable process from micro fractures developing to macro ＂wedge＂ sliding body,in order to reveal the microscopic mechanism of rib spalling,the damage mechanics theory is used and the connection of coal wall damage variability and the degree of fracture development is established;based on the measurement of rib spalling of high coal wall characteristics,the three-dimensional mechanical model of coal wall with ＂wedge＂ sliding stability analysis is set up,the main factors affecting its stability is analyzed,the rib spalling macro mechanism is revealed,high rib spalling control technique is proposed.（4） The coal wall stability control is put into the system of stope support-surrounding rock control system,the concepts and calculation methods of support equivalent resistance and equivalent protecting force are proposed,the interaction mechanism of high seam mining stope ＂Coal wall-Roof-Floor＂ space rock movement and the support working state is revealed.（5） The stope support-rock interaction relationship is researched using the system dynamics method,the SD model of high seam mining stope ＂Coal wall-Roof-Floor-Support＂（W-R-F-S） system is initially established,through the simulating by Vensim simulation software,quantitative description of ＂W-R-F-S＂ system stability under different control conditions is achieved.（6） The above results are applied and validated in the Xutuan 7219 working face of Huaibei Coal Mining Group and Sijiazhuang 15104 working face of Yangquan Coal Mining Group,the pressure regulation,coal wall spalling features and support-rock interaction relationship of the typical high seam mining stope are measured in in-situ situation.