等值反磁通瞬变电磁法在金矿采空区探测中的应用

Application of the opposing coils transient electromagnetic method in investigation of mined-out areas of a gold deposit

甘肃省玛曲县大水金矿是西秦岭地区的典型矿山之一,由于矿山的连年持续开采,导致在5号、9号高陡边坡下方形成一系列不同埋深的采空区,引起局部地面塌陷,存在较大安全隐患,根据环保及安全方面的要求,急需查明隐伏塌陷的空间展布特征,有效预防地质灾害的发生。本次研究采用等值反磁通瞬变电磁勘探技术,通过对勘察区典型断面图异常特征的精细解释,结合勘察区水文地质、基础地质等资料的综合分析,进而实现矿山隐伏塌陷的透明化、立体化。研究结果表明:利用等值反磁通瞬变电磁法(OCTEM)进行地下采空区探测,能够较好地反映采空区隐伏地层的岩性电性特征,并且采空区与围岩的物性差异明显,可有效查明地下采空区的空间位置及基本形态特征。同时基于多勘探线物探剖面采空区边界特征点数据,结合计算机三维建模技术,可实现采空区空间形态三维可视化,透视采空区的立体特征。等值反磁通瞬变电磁法的实施效果及三维建模技术为矿山恢复治理及安全评价提供了技术依据,可以有效服务于数字矿山的建设。

The Dashui gold deposit in Maqu County,Gansu Province is a typical mine of the western Qinling region.Owing to continuous mining,many mined-out areas have been formed at different depths below high and steep slopes No.5 and 9,causing local surface collapse and major safety hazards.According to the requirements for environmental protection and safety,there is an urgent need to determine the spatial distribution of concealed collapse to effectively prevent geological disasters.Using the opposing coils transient electromagnetic method(OCTEM),this study conducted the fine-scale interpretation of the anomalies on the typical sections of the exploration area.Based on this,as well as the comprehensive analysis of the hydrogeological data and basic geological data of the exploration area,this study determined the transparent and three-dimensional distribution of the concealed collapse of the Dashui gold deposit.The results of this study show that the subsurface investigation of mined-out areas using the OCTEM can effectively reveal the lithologic and electrical characteristics of concealed strata in mined-out areas.Moreover,the significantly different physical properties between mined-out areas and surrounding rocks can be used to effectively identify the locations and basic morphologies of subsurface mined-out areas.The data on the boundary characteristic points of the mined-out areas on geophysical profiles with multiple exploration lines and three-dimensional modeling allow for the three-dimensional visualization of the spatial morphology of the mined-out areas.The application performance of the OCTEM,along with three-dimensional modeling,provides a technical basis for mine restoration and safety evaluation,thus effectively serving the construction of digital mines.