硬岩矿床组合型井筒保安矿柱圈定与压覆资源回采技术

Delineation of Safety Pillars and Overlying Resource Recovery Technique inCombined Type Shafts of Hard Rock Deposits

为合理留设硬岩矿床充填开采时的井筒保安矿柱尺寸,考虑硬质围岩的岩体质量等级和自身抗变形、抗破坏能力,在常规岩层移动角圈定方法的基础上提出了组合型井筒保安矿柱留设方案。以山东某铁矿东主井压覆资源开采为研究背景,通过现场调查与岩石力学试验开展了工程地质分区与岩体质量等级评价,根据分级结果将-250 m水平以上的Ⅱ~Ⅳ级围岩按岩层移动角圈定台体状井筒保安矿柱,-250 m水平以下Ⅱ级硬质围岩按极限距离80 m圈定圆柱形保安矿柱,同时设计了两种井筒压覆资源开采方案,即浅孔留矿法嗣后充填开采与上向水平分层充填开采。研究表明:上向水平分层充填开采对应的井筒内壁变形量为浅孔留矿法嗣后充填开采的80%,但两种开采方案引起的井筒变形均未超过安全标准。所提出的上向水平分层充填开采方案与组合型井筒保安矿柱留设法在该矿山得到了成功应用,回收矿量约400万t,可为其他类似矿山的井筒压覆资源开采提供借鉴。

In order to reasonably set the size of shaft safety pillar in filling mining of hard rock deposit,considering the quality grade of hard wall rock and its own deformation and failure resistance,a combined shaft safety pillar retaining scheme is proposed on the basis of the conventional rock movement angle delineation method.Based on the study background of overlying resource mining in the east main shaft of an iron mine in Shandong Province,the engineering geological zoning and rock mass quality grade evaluation are carried out through field investigation and rock mechanics test.According to the classification results,for the surrounding rocks with quality ratings of classⅡ~Ⅳabove-250 m,the blockage shape safety ore pillars were delineated by movement angle of rock layers.For the harder rock masses rated as grade-250 m,cylindrical safety pillars were defined with a maximum distance of 80 m from the shaft centerline.In addition,two backfill mining schemes for shaft overlaying resources were designed,that is,the post-filling mining with shallow boreholes and the upward horizontal layered backfill mining.The study results indicated that the displacement of inner shaft walls of the upward horizontal layered backfill mining was 80%that of the post-filling mining with shallow boreholes.However,the shaft deformation caused by the two mining schemes did not exceed the safety standard.The proposed mining scheme of the upward horizontal layered backfill mining and combined shaft safety pillar retaining scheme have been successfully applied in the mine,and the recovered ore volume is about 4 million t,which can provide reference for the mining operation of wellbore overlaying resources in other similar mines.