动静组合作用下大跨度凿岩硐室稳定性分析

安徽某铜矿采用大直径垂直深孔阶段矿房法开采,首采采场开采深度为800 m,跨度达到30 m,爆破振动对周边岩体及采场结构产生了极大扰动,加之大爆破过程引发岩体能量的释放和转移,极有可能形成采场主要结构失稳,威胁回采安全。为研究大跨度凿岩硐室在动静组合作用下的稳定性,依据矿山实际情况,利用FLAC3D5.0数值模拟软件对该矿首采矿段201大跨度凿岩硐室在动静荷载组合作用下的稳定性进行了数值模拟分析,并与现场监测结果进行了对比。研究表明:开采过程中,最大主应力以及塑性区主要集中于条柱上,顶板在失去条柱支撑后位移增加较大,条柱支撑作用明显;开采结束后,条柱全部回采,顶板位移达到最大值,间柱成为主要支撑结构,整个开采过程中凿岩硐室较为稳定,分析结果与监测结果相吻合。建议后续开采之前适当增加凿岩硐室条柱宽度并实施锚网联合支护以提高抗压能力;通过优化爆破参数降低爆破振动对顶板的影响,并对凿岩硐室中间区域的顶板施加长锚索支护;对模拟分析和监测中容易出现破坏的区域进行布点监测,为后续开采中地压灾害防治提供有价值的信息。

Stability Analysis of Large-span Rock Drilling Chamber under Dynamic and Static Combination

A copper mine in Anhui Province adopts a large-diameter vertical deep-hole stage chamber mining method.The first mining stope has a mining depth of 800 m and a span of 30 m.The blasting vibration greatly disturbs the surrounding rock mass and the stope structure，and the rock mass energy is induced by the large blasting process. The release and transfer are likely to form the main structural instability of the stope and threaten the safety of mining.In order to study the stability of large-span rock drilling chamber under the action of dynamic and static combination，according to the actual situation of the mine，based on FLAC3D 5.0 numerical simulation software，numerical simulation analysis of the stability of the 201 large-span rock drilling chamber in the first mining section of the copper mine under dynamic and static load combination is done，and the comparison analysis of the numerical simulation results and on-site monitoring results are conducted.The study results show that:during the mining process，the maximum principal stress and plastic zone are mainly concentrated on the column，the displacement of the roof is increased after the support of the column is lost，and the support of the column is obvious；after the mining is completed，all of the columns are recovered and the displacement of the roof is reached，the maximum value of the column becomes the main support structure，the rock drilling chamber is relatively stable during the whole mining process，and the analysis results are consistent with the monitoring results.It is recommended that the width of the rock-filled chamber column should be appropriately increased before the subsequent mining and the joint support of the anchor net can be implemented to improve the pressure resistance；the influence of the blasting vibration on the roof can be reduced by adjusting the blasting parameters， and long anchor cable support of the roof of the middle part of the rock chamber can be conducted；the monitoring of the vulnerable areas in the simulation and monitoring results can be carried out to provide valuable reference information for avoiding geostress disasters in the subsequent mining process.