水砂—胶结充填隔离矿柱稳定性及宽度研究

Study on Stability and Width of Isolated Pillar Between Water Sand Backfill and Cemented Backfill

某嗣后充填矿山前期水砂充填泌水效果不佳,充填体富水,随着水砂充填区域增大,开采过程中顶板及上盘稳定性变差,为改善开采安全状态,改用胶结充填,水砂充填区与胶结充填区之间的隔离矿柱是保证未来采矿安全的关键。构建了侧壁承压倾斜矿柱理论分析模型,并采用FLAC3D数值模拟软件对10~15 m宽度水砂—胶结充填隔离矿柱和不同水砂充填体静水压力梯度进行了研究。研究表明:①开采扰动会使隔离矿柱内形成应力集中,且未凝固的水砂充填体会进一步增加矿柱内最大主应力;②矿柱内部应力重分布及水砂充填体水平压力使得矿柱水平变形增加,逐步产生破坏形成塑性区,10~13 m的隔离矿柱不足以保障充填体含水工况下的采场稳定性;③考虑到爆破扰动的影响,在现有富水充填情况下,建议隔离矿柱宽度为15 m;④隔离矿柱宽度15 m时,随着静水压力梯度增加,矿柱内部最大主应力和水平变形会有所增长,但塑性区未发生明显增加,15 m宽的隔离矿柱可以保障后续开采安全。

The water sand filling method was used in the early stage of a subsequent filling mine,and the water secretion effect of the filling body was poor,and the filling body was rich in water.With the increase of water-sand filling area,the stabil-ity of roof and hanging wall of the stope becomes worse.In order to improve the mining safety,the mining enterprise adopt the cemented filling method.Therefore,it is urgent to set isolated pillar between water sand filling body and cemented filling body to ensure the safety of subsequent mining activities.In this study,the theoretical analysis model of side wall pressure inclined pillar is constructed,and the hydrostatic pressure gradient of 10~15 m width water sand-cemented filling isolated pillar and dif-ferent water sand filling bodies is studied by FLAC3D numerical simulation software.The study results show that:①Mining dis-turbance will cause stress concentration in the isolated pillar,and the non-solidified water sand filling body will further increase the maximum principal stress in the pillar.②The redistribution of the stress of the pillar and the horizontal pressure of the wa-ter sand filling body increases the horizontal displacement of the pillar,and gradually produce damage and form a plastic zone.The 10~13 m isolated pillar is not enough to support the stability of the stope under the water bearing condition of the filling body.③Considering the influence of blasting disturbance,in the case of existing water rich backfill,the recommended isolated pillar width is 15 m.④When the width of isolated pillar is 15 m,with the increase of hydrostatic pressure gradient,the maxi-mum principal stress and displacement in the pillar increase slightly,and the plastic zone does not increase significantly,indi-cating that the 15 m isolated pillar can ensure the safety of the stope in the mining process.