煤巷弱胶结顶板稳定性分析与变形控制技术

煤层顶板为弱胶结岩体时稳定性差，常在煤炭回采过程中或巷道掘进时发生大变形或失稳等现象，维护难度较大。针对煤巷弱胶结粉砂岩顶板力学特征与变形控制等问题，以广西林场煤矿煤巷弱胶结粉砂岩顶板支护工程为工程背景，采用现场调研、实验室试验、理论分析等方法进行研究。通过现场调研，发现研究巷道有顶板岩层自承能力差、受水环境影响、支护结构失效率高、底板受水影响底鼓量大、受采动影响等特征；顶板岩石点荷载试验表明，其单轴抗压强度仅为1.9～ 2.3 MPa，采用电镜扫描发现，弱胶结粉砂岩以粗粒矿物为骨架；在普氏理论的基础上，推导了巷道顶板和两帮承压极限表达式，提出了提高巷道围岩整体强度和承载能力、确定合理的锚杆支护参数、顶板设计锚索加强支护等弱胶结巷道围岩控制要点。依据试验分析与理论研究成果，提出了以注浆加固为基础，锚杆和锚索联合支护的控制方案，并在林场煤矿进行了工业性试验。现场监测数据表明，设计的支护方案可以有效地控制煤巷弱胶结粉砂岩顶板变形。

Stability analysis and deformation control technology for weakly cemented roof of coal roadway

The weakly cemented rock mass makes poor stability. Large deformation often occurs during coal mining or roadway excavation, which brings maintenance difficulties. To address the problems of the mechanical characteristics and deformation control of the surrounding rock of the weakly cemented siltstone, we performed the field survey, laboratory tests, theoretical analysis by selecting Linchang coalmine in Guangxi Province of China as the engineering background. On-site investigations show that the roof rock layer of roadway has poor self-supporting ability, high failure rate of supporting structure due to water effect; large floor heave occurs affected by water and mining. The point load test indicates that the uniaxial compressive strength is only 1.9?2.3 MPa. Scanning with an electron microscope reveals that the weakly cemented siltstone is based on coarse-grained minerals. According to Protodyakonov’s pressure arch theory, we derived the equations of ultimate bearing capacity of roof and two sides and put forward the key points of weakly cemented roadway surrounding rock control, including improving the overall strength and bearing capacity of roadway surrounding rock, determining reasonable bolt support parameters, designing roof anchor cable to strengthen support. Based on the results of experimental analysis and theoretical research, we proposed a control plan based on grouting reinforcement, combined with bolts and cables, and carried out industrial tests in Linchang coalmine. The monitoring data show that the designed support scheme can effectively control the deformation of the weakly cemented siltstone roadway.