大倾角煤层长壁采场人工与垮落矸石复合充填体耦合控制覆岩作用机理研究

The steeply dipping seam, the coal seam pitch between 35°-55°, is regarded as the most difficult mining seam by international mining industry. The core of its safety and high efficient mining depends on the proper control of its surrounding rock. During longwall mining in steeply dipping seam, a composite artificial-caving rock filling body can effectively control the movement and deformation of overlying strata. However, the theory of composite filling body for controlling overlying strata has not been systematically and thoroughly studied, and its mechanism is yet to be determined. Using a four-in-one mutual feedback method of “experimental study – theoretical analysis – field testing – engineering practice”, this project will examine the filling properties, compressibility and interactive mechanism of composite artificial-caving rock filling body before and after the roof of longwall mining area in steeply dipping seam caves, after analyzing the compressibility of collected rock samples, and investigate the stress spatial distribution, evolution mechanism and moving feature of overlying strata during composite backfill mining under multi-factor interaction (e.g. dip angle, filling volume), and analyze the type of loading and interaction equilibrium relationship between overlying strata and composite filling body, and establish a mechanical and mathematical model for overlying strata control that reveals the coupling control mechanism of composite filling body. This research can provide a theoretical basis and technical support for controlling strata movement and pressure behavior of longwall mining area in steeply dipping seam.

大倾角煤层是指倾角为35°-55°的煤层，是国际采矿界公认的难采煤层，其安全高效开采的核心在于采场围岩的有效控制。大倾角煤层长壁开采条件下，人工与垮落矸石形成的复合充填体可有效的控制覆岩移动变形，但其理论方面迄今尚未开展系统、深入的研究，作用机理尚不清楚。本项目拟采用“实验研究-理论分析-现场测试-工程实践”四位一体互馈研究方法，在对采集的矸石样本进行压缩性能实验分析的基础上，系统研究大倾角煤层长壁采场多因素（倾角、充填量等）交互影响下顶板垮落前后人工与垮落矸石复合充填体充填特征和压缩特性及相互作用机理，揭示该条件下覆岩应力空间分布及演化特征和岩层运移规律，通过分析覆岩对复合充填体载荷作用类型以及相互作用平衡关系，建立覆岩控制力学及数学模型，阐释复合充填体耦合控制覆岩作用机理。项目研究成果可为解决大倾角煤层长壁采场岩层运动和矿压显现控制等关键技术提供理论依据和技术支持。

大倾角煤层是指倾角为35°-55°的煤层，是国际采矿界公认的难采煤层，其安全高效开采的核心在于采场围岩的有效控制。大倾角煤层长壁开采条件下，人工与垮落矸石形成的复合充填体可有效的控制覆岩移动变形，但其理论方面迄今尚未开展系统、深入的研究，作用机理尚不清楚。本项目采用“实验研究-理论分析-现场测试-工程实践”四位一体互馈研究方法，在对采集的矸石样本进行实验分析的基础上，系统研究大倾角煤层长壁采场多因素（倾角、充填量等）交互影响下对大倾角煤层复合充填采场覆岩应力场和位移场的变化规律、矿压显现规律和复合充填体耦合控制覆岩作用机理。.在综合分析大倾角煤层复合充填采场围岩运移影响因素下，通过数值模拟（Flac3D、Udec)和可变角度物理相似模拟实验研究多因素（倾角、埋深、采高、充填量、充填体强度）交互影响下覆岩的应力场空间分布特征和演化机制，以及覆岩移动、变形和破坏特征；采场顶板垮落前人工充填矸石和顶板垮落后与自然垮落矸石复合充填特征，掌握复合充填体的尺度效应。在上述分析的基础上，结合试验工作面的矿压观测，揭示了复合充填采场矿压显现规律。对大倾角煤层复合充填开采顶板受力分析的基础上，建立了复合充填采场充填体控制覆岩采场倾向顶板力学模型，推导了顶板岩梁挠曲微分方程，利用方程求解了充填区域和未充填区域的最大挠度位置，明确充填开采对覆岩应力分布特征及顶板岩层破断方式的影响，分析了不同倾角、埋深、充填量和工作面长度条件下顶板岩梁的变形规律，揭示了复合充填体耦合控制覆岩的作用机理。.本研究为大倾角煤层充填开采基础理论研究提供了新的技术方法、思路和理论支撑，符合国家矿产资源绿色可持续开发等要求，具有重要的理论和现实意义。