浅埋厚煤层综放开采围岩控制与顶煤三维放出规律基础研究

In the western of China, there are abundant coal resources in shallow seams, and the fracture and movement rules of surrounding rock and roof stratum are different from general coal seams during the mining. Based on the structural feature of overburden stratum after coal mining, the scientific definitions of thin bedrock and shallow seam were offered. Under the conditions of different stratum structures and mining methods, the distributional pattern, value and evolution low of stope stress were in-depth studied. The mechanism of action between fully mechanized top-coal caving supports and surrounding rock was analyzed and same to the determination method on reasonable effective resistance of support in thin bedrock and shallow seam. The control and decision system of roof accident to top-coal caving was formed through determining the leading indicators of accident prediction and grasping the fracture evolution low and transfusion characters of bedrock aquifer. top coal 3-D running law was studied, which provide the basis for improving the recovery ratio of top-coal. These research involved core problems of large mining height roof controlling under the conditions of thin bedrock, shallow seam and loose aquifer. This project has great theoretical significance and practical value. The achievement could direct the security mining of similar coal seam, which will be the significant innovation both in ideas and technology in the subject area of coal mining.

本项目针对我国西部具有丰富的浅埋厚煤层资源，以及薄基岩浅埋特厚煤层综放开采过程中围岩与上覆岩层的运动、破坏具有特殊性的实际，基于上覆岩层开采后的结构特征对“薄基岩”和“浅埋煤层”进行科学定义，并对不同煤岩层结构条件、开采条件和开采方法情况下的采场应力分布形态、大小及演化规律进行深入研究，分析综放支架与围岩相互作用机理，提出薄基岩浅埋厚煤层综放支架合理工作阻力的确定方法，系统深入地研究采动作用下底板破坏裂隙演化规律与渗流特征，确定综放开采底板事故预测的主要指标，研究顶煤三维放出规律，为提高顶煤回收率提供依据。这些研究是涉及到浅埋深、薄基岩、厚松散含水层条件下综放开采顶板控制与提高回收率的核心问题，因此本项目的研究具有重大理论意义与实用价值，对于指导该类煤层的安全开采具有现实意义，同时也是煤矿开采学科领域在思想和技术上的重要创新。

本项目针对我国西部矿区浅埋厚煤层资源丰富现状及其赋存特点，从综放开采顶煤破碎机理、三维放出规律、上覆岩层移动规律、支架-围岩关系、煤壁破坏机理、顶板事故预测与控制等方面进行了深入研究。建立了煤岩体拉剪平行偏置双裂纹模型，计算了不等长平行偏置裂纹尖端的应力强度因子，通过其变化规律分析了裂纹间相互影响，并通过RFPA2D模拟进行了验证；研究了裂隙场影响下采动应力大小和方向的变化特征，建立了煤体渗透率同塑性体积应变之间的关系公式，进而提出了顶煤冒放性预测指标体系。建立了综放开采顶煤放出规律的BBR研究体系，科学阐述了顶煤放出体、煤岩分界面、煤炭回收率和含矸率之间相互影响关系；理论推导了综放支架影响下煤岩分界面及顶煤放出体理论方程；利用自主研发的三维顶煤放出模拟试验台，研究了多夹矸近水平厚煤层、急倾斜厚煤层等条件下综放开采三维顶煤放出规律，并通过顶煤运移跟踪仪在瑞隆、大远等矿进行了现场验证。提出了综放开采岩梁斜裂纹尖端的应力强度因子及老顶岩梁周期来压时断裂步距计算方法；分析了“两硬”孤岛型超短综放面顶板两种破断形式，以及煤体破坏范围与支承压力峰值之间的关系。建立了支架与围岩关系本构模型，通过自主研发的动载荷冲击实验平台，进行了综放支架与破碎顶煤缓冲动载荷模拟实验，表明支架刚度小，缓冲过程较平缓，而支架刚度较大时，支架产生的反弹力大，顶板容易破碎且不易支护；分析了急倾斜走向长壁综放开采支架与围岩关系，提出了“下行动态分段、段内上行放煤”的放煤方式，理论推导了支架侧护板所需抗挤压力大小。建立了含夹矸厚煤层仰斜开采煤壁剪切破坏力学模型，对各煤岩体力学参数进行了敏感性分析，揭示了煤壁破坏主要影响因素；提出了煤壁柔性棕绳注浆加固技术，并建立了“柔性棕绳-浆液-煤壁”柔性加固系统本构模型。通过对本项目的深入研究，对综放开采技术健康发展、安全高效生产、提高综放面回收率等具有重大意义。