板裂状围岩下薄矿脉开采稳定性相似模拟试验研究

Study on the analog simulation test on stability of mining thin vein under the splintering surrounding rock

赣南某钨矿矿体上下盘岩体多为板岩,结构面发育且岩体破碎,在留矿法放矿过程中,上盘岩体暴露后在次生应力的影响下极易发生板裂状滑落或溃曲破坏,使得采幅难以控制。针对此问题,提出了普通留矿法、静态留矿法、散体人工矿柱+锚固留矿法3种回采方法。通过分析上下盘板裂状围岩随开采过程的位移变形情况,最终选择散体人工矿柱+锚固留矿法作为试验采场回采方法。基于正交试验原理,进行了相似材料配比试验,最终确定的材料配比为ω(沙)∶ω(石膏)∶ω(水)=5.0∶1.0∶1.2。相似模拟试验结果表明:采高较小时,锚杆支护对控制围岩的稳定是有效的,然而随着采高的增大,采场出现应力集中,锚杆逐渐失去了作用,因此仅对围岩进行锚固支护并不足以改善地压环境;散体人工矿柱+锚固留矿法利用人工矿柱减小了回采跨度,提高了整个采场的稳定性。对比模拟结果可知,其上下盘及顶板的位移量远小于其他2种回采方法。

In a tungsten mine in South Jiangxi,both the hanging and foot wall rocks consist mostly of slates with developed structural planes and broken rocks.In the process of ore drawing by shrinkage method,as the hanging wall rocks lose their support and are exposed,they are prone to splinter sliding or flexural failure with the influence of secondary stress,resulting in the difficulty of controlling the mining volume.In order to solve the problem,three mining methods including general shrinkage method,static shrinkage method and anchoring shrinkage method with bulk artificial pillars were proposed.Through studying on the change of displacement of the hanging and foot splinter surrounding rocks in the mining course,the shrinkage method with the scattered artificial pillar to support anchoring was used for the mining tests in stope.Based on the principle of orthogonal experiments,the tests were carried out as a function of the ratio of similar materials,the material at ratio of sands to gypsum to water(5.0:1.0:1.2)was finally decided.Similar simulation test results show that when the mining height is small,the support of bolt is effective to maintain the stability of surrounding rock.However,with the increase of mining height and the concentration of stress on the mining site,the bolt functions less and less.Therefore,the anchoring support to surrounding rock is not enough to improve the ground pressure environment.The application of shrinkage method with support of bulk artificial pillars may reduce the mining span and improve the stability of whole mining site by means of the artificial pillars.By comparison of the simulation test results,the displacement of hanging and foot wall as well as roof when using this shrinkage method with support of bulk artificial pillars is far less than the rest mining methods.