浅埋弱胶结覆岩综放沿空留巷时变力学模型与协调控制机理

The overlying strata of shallow coalseam in the western Ordos Basin are weekly cemented with low strength. Adopting gob-side entry retaining in longwall face with top-coal caving is very difficult because roofs at both ends of coal face are easily cut off along the edge of roadway and the rock stratums move violently with large dynamic load. Laboratory test, theoretical analysis, numerical simulation and field testing are used in this research. The main innovative research work can be summarized as follows: (1)The mechanism of cracking evolution from micro to macro of weekly cemented rock and coal with different sedimentary formation were obtained, and the creep damage constitutive relation of weakly cemented rock mass was constructed based on crack fractal dimension. (2)The rock failure and movement characteristics of the gob-side entry retaining in weakly cemented shallow strata with top-coal caving under different ratios of bed rock to mining height were studied. Then, the mechanical model of overlying strata was built to reveal the evolution of overlying strata structure of gob-side entry retaining in weakly cemented shallow strata with top-coal caving. (3)The interaction between the gob-side supporting structure and the weekly cemented roof and its evolution were studied. And then, the creep coordinated controlling mechanism of gob-side entry retaining in weakly cemented shallow strata with top-coal caving was revealed and the corresponding design theory and method were put forward. This research firstly studied the gob-side entry retaining theory in weakly cemented shallow strata with top-coal caving systematically, and it can provide some theoretical foundations for the gob-side entry retaining in the similar conditions.

西部鄂尔多斯地区浅埋煤层覆岩强度低、胶结性差，顶板岩层易整体切落，动载冲击剧烈，给综放沿空留巷带来极大的困难。本项目拟采用试验研究、理论分析、数值模拟和现场测试相结合的方法，研究如下创新性内容：（1）在深入揭示浅埋弱胶结岩体（煤）从细观至宏观不同尺度破裂演化力学机理的基础上，基于裂隙分形维数构建弱胶结岩体流变损伤本构关系；（2）研究不同基采比条件下浅埋弱胶结覆岩综放沿空留巷顶板（顶煤）破坏及运动特征，建立沿空留巷顶板结构时变力学模型，揭示浅埋弱胶结覆岩综放沿空留巷顶板空间结构演化规律；（3）研究沿空留巷巷旁支护结构与弱胶结顶板相互作用关系及随时间变化规律，获得浅埋弱胶结覆岩综放沿空留巷围岩时变协调控制机理，并给出相应的支护设计理论与方法。本项目将首次对浅埋弱胶结覆岩综放沿空留巷理论进行系统深入研究，为西部浅埋弱胶结覆岩综放开采条件下实现沿空留巷提供理论支撑。

西部鄂尔多斯地区浅埋煤层覆岩强度低、胶结性差，顶板岩层易整体切落，动载冲击剧烈，给综放沿空留巷带来极大的困难。本项目采用试验研究、理论分析、数值模拟和现场测试相结合的方法，研究如下创新性内容：. （1）通过对浅埋不同沉积建造砂质泥岩细观结构、矿物组分及三轴加卸载力学试验，揭示了浅埋不同沉积建造弱胶结岩层破裂演化的微观力学机理，获得加卸载条件下浅埋弱胶结岩体（煤）应力-应变演化规律，微裂纹的形成、发展、贯穿形成裂纹群的演化力学机制及特征，基于裂隙分形维数构建弱胶结岩体流变损伤本构关系。. （2）基于阿吾孜苏煤矿4#煤层赋存及开采条件，采用相似材料模拟，研究了浅埋煤层综放面沿空留巷顶板破断演化规律，分析沿空留巷顶板及巷旁充填体在采动过程中的应力分布规律；对不同基采比条件下弱胶结覆岩综放沿空留巷顶板（煤）破断结构及应力场、位移场变化规律进行数值模拟，确定不同开采参数和覆岩组合条件下综放沿空留巷顶板破断结构空间演化规律。. （3）建了浅埋煤层沿空留巷“煤体-充填体-矸石”协调变形与控制模型，推演了沿空留巷支护系统协调变形与控制方程，确定了沿空留巷基本顶岩梁最佳回转角；根据沿空留巷支护系统协调变形、共同承载原理，提出了沿空留巷支护系统协调变形人为调控措施及定量设计方法。. （4）研发了具有一定强度并对顶板压力（或冲击力）起到强耗散作用的恒阻-让压柔性材料，利用粉煤灰、水泥、矸石颗粒等无机材料配置高强度膏体充填体。巷旁充填体由上述恒阻-让压柔性材料和高强度材料构成。. 项目研究成果在鄂尔多斯高家梁煤矿得到了应用，多回收煤炭93.3万t，新增销售额32664万元，新增利润11543万元。已获得发明专利10项，发表相关学术论文SCI收录13篇、中文核心期刊论文8篇，出版学术专著1部，中国煤炭工业协会组织的专家鉴定委员会认为“项目研究达到国际领先水平”，2018年获山东省科技进步三等奖。