露天开采台阶面下伏空区安全隔离层厚度及声发射监测

摘要

开采台阶面下存在空区危害的露天矿山很多,这些空区不仅包括之前常规地下开采遗留的空区,还有很多因民采、盗采形成的无资料记录的空区.经过多年的演变,这些空区的形状、大小都发生较大的改变,这直接威胁着露天台阶面作业人员及设备的安全,极大地制约了露天安全高效开采.以国内三道庄矿露天开采工程台阶面下伏空区为背景,运用数值模拟方法对台阶面下伏空区的安全隔离层厚度进行确定,通过模拟计算不同跨度、不同顶板厚度空区的稳定性,寻找出特定跨度下空区的安全隔离层厚度,进而得到不同跨度空区安全隔离层厚度速查表,为现场台阶面推进及空区处理提供必要的参考.同时,运用声发射监测技术对台阶面下伏空区进行监控,给出具有代表性空区的声发射监测数据,选取不稳定空区、稳定空区、台阶面有钻机作业空区、台阶爆破后空区的声发射监测数据进行分析,找出这些代表性空区声发射监测数据的规律,为后续声发射监测结果的解释提供参考.这样就可以在利用安全隔离层厚度对空区稳定状况进行初步评价的基础上,通过声发射技术实时监测空区的稳定性,从而为露天台阶面作业提供有效的安全保障.%There have many open pits in China threatened by cavities under open pit benches because of former unreasonable underground mining. Shape and size of these cavities were greatly changed through many years' mining activity. There have no clear figures or data to show how these cavities occurred. This would greatly restrict high-efficient and safe mining. Thus, the reasonable safety isolation layer thickness of cavity should be properly calculated, and the feasible stability monitoring method for this kind of cavity should be employed to well ensure safety of personnel and equipments on open pit benches. Based on the present situation of Sandaozhuang open pit of Luoyang Luanchuan Molybdenum Group Inc., which has lots of cavities under its benches, the safety isolation layer thickness corresponding to different roof spans, which can provide a primary evaluation for cavity stability, was obtained through numerical modeling. Acoustic emission technique was used to monitor the cavity stability. Monitoring data of four types of cavity, i.e. unstable cavity, stable cavity, cavity with drill and cavity after blasting, which are all the typical ones under open pit benches, were listed. The signals of acoustic emission of those cavities were analyzed to obtain acoustic emission characteristics of typical cavities under open pit benches. This will provide reference for following accurate stability evaluation of cavities under open pit benches that are monitored by acoustic emission technique. Thereupon, the efficient safety guarantee system of open pit benches with cavity would be established through primary evaluation according to safety isolation layer and stability monitoring by the acoustic emission technique.