基于普氏冒落拱理论的矽卡岩型底部结构支护优化研究

Study on the optimization of skarn type bottom structure support based on the theory of Platts caving

针对某铁矿复杂破碎大水矽卡岩型底部结构节理裂隙发育、岩石强度低、遇水易膨胀,以及现有锚网喷支护方式效果不理想等难题,本文展开支护参数优化研究。首先根据室内膨胀性试验确定矽卡岩岩体物理化学性质,其次以普氏冒落拱理论为巷道支护原则,采用理论计算与数值模拟方式确定矽卡岩底部结构支护参数,最后通过现场监测分析确定矽卡岩底部结构合理的支护参数合理性。室内膨胀性试验表明,现场矽卡岩中的黏土矿物遇水极易膨胀,20 h吸水后膨胀率达到85.06%。数值模拟结果表明,增加预应力锚索后巷道变形量明显变小,由30 d巷道收敛现场监测结果可知,顶底板及左右帮位移累计量仅为52 mm和39 mm。研究结果表明,矽卡岩型巷道开挖后应迅速进行素喷工序封闭,素喷+锚杆+预应力锚索联合支护技术可以有效解决某铁矿底部结构巷道围岩稳定控制难题,保证出矿进路在使用期限内的基本稳定和矿体安全高效回采及主要穿脉的长期稳定。

In view of the supporting difficulties of complex broken and large water skarn bottom structure of an iron mine,such as support difficulties such as the development of joints and fissures,low rock strength and easy expansion in case of water,the existing bolt-net shotcrete support method is not ideal,and the optimization of supporting parameters is carried out.Firstly,the physical and chemical properties of skarn rock mass are determined according to laboratory expansibility tests.Secondly,the reasonable supporting parameters of skarn bottom structure were determined by theoretical calculation and numerical simulation based on the theory of caving arch as the roadway supporting principle.Finally,the reasonable supporting parameters of skarn bottom structure were determined by on-site monitoring analysis.The experimental results show that the clay minerals in skarn are easy to expand in water,and the expansion rate reaches 85.06%after 20 h of water absorption.The numerical simulation results show that the deformation of roadway decreases significantly with the addition of prestressed anchor cables.According to the field monitoring results of roadway convergence for 30 days,the cumulative displacement of roof,floor and left and right sides is only 52 mm and 39 mm.It indicates that the skarn roadway should be quickly closed by shotcrete process after excavation.The combined support technology of shotcrete+bolt+prestressed anchor cable can effectively solve the problem of surrounding rock stability control of tunnel with bottom structure in an iron mine,and can guarantee the mining approach during the term of use basic stability and orebody safe and efficient mining and main wear vein of long-term stability.