某铅锌矿巷道围岩破坏原因及治理对策分析

为了澄清1 330 m中段巷道发生冒顶、片帮及底鼓的原因,并预测深部各中段巷道的地压显现规律及治理对策,应用FLAC3D模拟实际开挖和开采过程,并分析巷道围岩的应力变化。结果表明:巷道地压显现是拉应力长期作用而发生疲劳拉坏的结果;南侧矿体无断层与巷道贯通,且离1 330 m中段巷道较远,其开采对巷道稳定性影响微弱;北侧矿体有正断层与巷道贯通,离巷道水平距离只有10 m,其开采是引起巷道围岩拉应力增大的主要原因,贯通断层是引起巷道围岩拉应力增大的次要原因;深部巷道应布置在矿体下盘分界线以外不小于15 m处;鞍部矿体采空,有利于1 330 m中段巷道卸压,对1 280 m中段巷道卸压效果微弱;确保断层附近顶柱的完整性,有利于降低巷道围岩的拉应力;对拉伸疲劳破坏的巷道,采用无预应力锚杆支护几乎不起作用。该结论与开挖、开采实践基本吻合。

Analysis of the causes leading to the surrounding rock damage and countermeasures to be taken in a sampling lead zinc mine

This paper is intended to make a survey of the factors leading to the roof collapse,spalling and heaving floor at 1 330 m level roadway,so as to be able to control the regularity of the ground pressure in the deep roadway. For the said goal,we have simulated the actual excavation and the mining process so as to be able to control the stress changes of the surrounding rock via a software known as FLAC3D. The results of our survey and simulation show that the roadway ground pressure comes up due to the long-term effect of the tensile stress,which leads to the tensile fatigue failure. Whereas the southern ore section can get rid of the fault due to its being far away from the 1 330 m level roadway,it tends to have minor effect on the roadway stability in its exploitation of mining ore. On the contrary,the northern ore body with the normal fault is only 10 m away from the roadway through with the 1 330 m level roadway. Actually the mining activity on the northern side serves as the main factor accounting for the increase of the tensile stress of roadway surrounding rock. The secondary factor is to link up the fault. For example,when the deep roadway should be arranged at the foot wall boundary outside at a distance of over 15 m,the saddle ore body is actually being mined, which would be beneficial to relieve the pressure of the tunnel at the 1 330 m level roadway,which brings about merely slight effect at the level of 1 280 m. Therefore,in order to ensure the integrity of the pillar prop near the fault area,it would be better to reduce the tensile stress of surrounding rock. Nevertheless, non pre-stressed anchor support can be found merely minor effect on the tensile fatigue damage of the roadway. Thus,the conclusions we have made prove to be consistent with the practical experience of excavation and mining exploration. Hence,it can be seen that the innovation of this paper lies in its successful application of the numerical simulation software of FLAC3D,by bringing into reality the multi-dimensional simulation of the ore-body with or without extraction and existence or nonexistence of the likely faults. Therefore,this paper has brought forward reasonable,feasible and applicable countermeasures to overcome the roadway surrounding rock failure in a lead zinc mine,so that the effective control of the failure of the surrounding rock of the mine can be successfully realized.