特大断面巷道软弱厚煤层顶板控制对策及安全评价

SAFETY CONTROL AND EVALUATION OF ROADWAY WITH SUPER-LARGE CROSS-SECTION AND SOFT-WEAK THICK COAL ROOF

针对特大断面巷道软弱厚煤层顶板支护过程中出现大变形甚至冒顶灾害控制难题,以及现有顶板安全性评价方法存在的突出问题,综合现场调研、理论分析、井下试验及现场实测方法,分析巷道在锚杆(索)支护下的顶板控制难题及安全性评价方法的不足,提出均分断面两次成巷与"多支护结构体"控制系统,详细研究新支护系统组成结构、控制原理、顶板安全性判定因素、安全评价因子。由此可以得出:(1)特大断面巷道软弱厚煤层顶板大变形根源在于顶板支护结构弱、顶帮协同控制弱及顶板中部承受拉应力大;(2)"多支护结构体"控制系统形成全煤顶帮协同控制结构、浅顶板锚固体厚板结构和深顶板索块体承载体结构,大幅降低顶板离层变形和强化顶帮协同支护;(3)提出顶板安全性判定的10个关键指标,计算得出特厚煤层顶板安全分区和安全评价因子,开发特厚煤层巷道顶板支护安全性判定系统;(4)详细介绍井下运用均分断面两次成巷与"多支护结构体"控制系统的典型特大断面巷道软弱顶板成功实例。研究成果在五家沟煤矿进行推广应用,对类似条件工程的支护技术具有一定的理论意义和参考价值。

Field observation,theoretical analysis and in-situ tests and monitoring were carried out in order to tackle the problem of large deformation and roof caving of roadways with super-large cross-sections and soft and weak coal roofs. The reasons of the problem were found to be the weak supporting structure of the roof,the weak connections between the roof and the two side walls of the roadway,and the occurrence of large tensile stress in the middle span of the roof. It was therefore proposed that the cross section of roadway to be equally divided into two parts for excavation one after another with multiple supporting structure（MSS） to strengthen the roof and roof-sidewall connection and reduce the deformation of the roof. A total of 10 factors were found to be vital to evaluate the roof safety. The proposed method was successfully applied to the coal mine at Wujiagou.