Comprehensive research on character of collapse and fracture of thick and large overburden rock in cave mining
- 建筑土木－已发表论文 
大红山铁矿采用无底柱分段崩落法开采,形成了规模巨大的采动区域,上覆岩层厚度达627~750 m。为了掌握上覆岩层中崩落、开裂与高应力集中区的范围及发展趋势,防止突发性的大规模动力地压灾害的发生,矿山采取多通道微震监测技术、巷道观测和钻孔探测相结合的方法,对上覆岩层进行全面监测和研究。通过多通道微震监测技术对上覆岩体中高应力集中区破裂源进行高精度定位,确定高应力集中区及其变化过程,并据此推断开裂带的外边界;同时基于双力偶点源理论,分析得到震源破裂类型为以体积增加的张拉型为主、压剪切破坏与混合破坏为辅。在专门的巷道中,通过人工直接观察,确定崩落边界、开裂带的内、外边界;地表深钻孔探测作为辅助性手段,用来确定(验证)开裂带的外边界。将这3种技术手段结合起来对2011~2013年间上覆岩层不同时期的崩落带、开裂带与高应力集中区进行综合监测,得到不同时期高应力区、开裂带和崩落带的发展过程。研究表明,上覆岩层中崩落与开裂发展过程是一个缓慢渐进的过程,不会产生大规模的突变型崩塌冲击地压灾害。本文研究成果对矿山的安全生产具有重要的指导作用。A bulky mining-out area was formed at Dahongshan iron mine with sublevel caving method. The thickness of overburden is 627 to 750 meter. In order to understand the development of collapse area,fractured zone and high stress concentration zone in overburden so as to prevent the sudden large-scale and dynamic ground pressure disasters,micro-seismic monitoring,tunnel observation and borehole detection methods were used to carry out the comprehensive monitoring and research. Base on the precise location of fracture source with multi-channel micro-seismic monitoring technology,high-stress concentration zone and its developing trend were determined,and then the outer boundary was deduced. At same time,the analysis on fracture types of fracture source with double couples model showed that the tension fracture with volume-increasing accounted for majority of all sources,while the shear failure and mixed failure accounted for minority. The boundary of collapse area,external and internal boundaries of fractured area were determined directly through the artificial observation in special tunnels. The borehole detection as the auxiliary method was used to determine and validate the external boundary of fractured zone. A comprehensive monitoring and analysis were carried out to obtain the caving zone,cracking zone and high stress concentration area in overburden in different periods from 2011 to 2013. The development of high stress zone,cracking zone and caving zone in different periods were also obtained. The studies showed that the caving and cracking processes in overburden were slow and gradual. The sudden and dynamic large-scale collapse disaster would not occur. The conclusion of this paper played an important role in guiding the safe production of the mine.