基于水平构造应力比圈定新城金矿竖井保安矿柱初探

在以往的竖井保安矿柱圈定过程中,岩层移动角是主要的考虑因素,地应力条件则通常不被重视。而对于水平构造应力显著的矿山,在回采扰动下竖井周边易形成应力集中区,不利于竖井稳定。新城金矿水平构造应力突出,为了在圈定竖井保安矿柱时考虑水平构造应力作用,建立了竖井周边采矿的概念模型,模拟在不同水平应力条件下开采对竖井围岩变形及应力的影响。研究表明:当采空区位于竖井的最大主应力方向上时,回采具有显著的卸压作用,可以减小水平构造应力对竖井的影响,变形场主要集中于采空区周边,且竖井围岩也向采空区挤压变形;在竖井的最小主应力方向回采矿体则会加剧竖井处的应力集中,竖井围岩呈现出整体向井筒内部加剧挤压变形的趋势。在此基础上,建立了新城金矿竖井与矿体的大尺度数值计算模型,对比分析了圆形保安矿柱方案与根据水平应力比圈定的椭圆形保安矿柱方案,结果表明:针对新城金矿的地应力及矿体条件,目前保留100 m的竖井保安矿柱为较优方案。

Preliminary Study on the Determination of Shaft Pillar Based on the Ratio of Horizontal Tectonic Stress

In the past,the displacement angle of stratum is the main factor to be considered in the shaft pillar delineation,while the geostress is usually ignored.For the mine with significant horizontal tectonic stress,stress concentration is easy to occur around the shaft during mining,which is not conducive to the stability of the shaft. The horizontal tectonic stress of Xincheng Gold Mine are prominent,in order to delineate the shaft pillar with consideration of the horizontal tectonic stress,a conceptual numerical model was firstly established to investigate the effect of mining on the deformation and stress of shaft surrounding rock under different horizontal stress conditions.The study results show that when the goaf is oriented to the direction of the maximum principal stress of the shaft,mining is beneficial to the stress relief and also reduce the influence of horizontal tectonic stress on the shaft,the deformation field is mainly concentrated around the goaf and the surrounding rock of the shaft also deforms towards the goaf;while mining in the direction of the minimum principal stress of shaft,the level of stress concentration around the shaft is enhanced,and the surrounding rock of the shaft aggravates the extrusion deformation towards the inside of shaft.Based on the above discussion results,a large-scale numerical model was established with both the shaft and orebody at Xincheng Gold Mine included,and the circular shaft pillar was compared with the elliptical one that delineated according to the horizontal tectonic stress.It indicates that accounting for the horizontal tectonic stress and the location of orebody at Xincheng Gold Mine,the shaft stability can be maintained by retaining the shaft pillar with a radius of 100 m.