房柱式开采磷房冒顶原因分析与支护设计

Reason analysis and supporting design of roof caving in room and pillar mining of phosphate rock

为解决开磷集团房柱式采掘过程中磷房经常冒顶问题,在对工程开采现状和冒顶事故现象总结的基础上,分析了磷房冒顶原因,直接顶岩性较差是根本原因,支护结构和强度不合理是主要原因,开采影响是直接原因。通过顶板受力分析和支护原则确定,提出了适合于该顶板条件下的"锚索+槽钢+金属网"的优化支护设计对策,放弃使用锚杆;并采用FLAC^(3D)数值模拟软件对支护效果进行验证,结果显示:磷房开挖时,应力重新分布,锚索受力急剧增加,顶板快速下沉,并逐渐趋缓;达到新的平衡时,锚索受力约275 k N,顶板最大下沉量23 mm,顶板作用力向磷柱转移。经分析可知:"锚索+槽钢+金属网"的优化支护对策可对整个直接顶起悬吊作用,并通过锚索预应力扩散有效提高直接顶板整体性,成功阻止顶板冒落。同时,也为同类房柱式顶板支护设计提供了工程依据。

In order to solve the problems of roof caving in the pillar mining process of Guizhou Kailin（ Group） Co.,Ltd.,based on summarizing the status quo of mining and the phenomena of roof fall accident,the reason for roof fall of phosphorus house was analysed,the poor lithology of immediate roof is the root cause,unreasonable supporting structure and strength is the main reason,and mining effect is the direct reason. Through the analysis of roof stress and the principle of supporting,the optimized supporting scheme was proposed in the paper,which was defined as ＂ anchor ＋ U-steel ＋ metal mesh＂,and was suitable for the conditions of roof. Bolt was abandoned in this design. And the FLAC-（3D） numerical simulation software was used to verify the supporting effect. Results show： the stress redistribution in the excavation of the phosphorus house,at same time anchor force increased dramatically,roof sinking fast and gradually slowed down;when it reaches a new balance,the anchor cable is under the force of about 275 k N,the roof of the maximum sinking 23 mm,the roof force transfers to the phosphorus column. From the above analysis,it can be known that,the optimized ＂ anchor ＋ U-steel ＋ metal mesh＂ supporting engineering design has the suspension function for the entire immediate roof,and the direct roof integrity is effectively improved by the spread of anchor cable prestress,successfully prevent roof caving. Meanwhile,it also provides the engineering basis for the design of the same kind of room pillar roof supporting.