北京地区浅层采空区高密度电法探测应用分析

Analysis and Applications of Shallow Underground Goaf Detection Using High-density Electrical Method in Beijing

高密度电法已广泛应用于煤层采空区探测之中,采空区充填性质的不同造成其在高密度电法数据剖面中的表现特征也不相同。本文主要介绍运用高密度电法进行浅层小煤窑采空区探测的一些经验和案例。采用高密度电法中的温纳装置对门头沟地区未充填、部分充填的小煤窑巷道和石景山区富水充填的小煤窑采空区的探测,取得了很好的效果。探测结果显示,未充填和部分充填的小煤窑巷道表现为高视电阻率异常,位置与测线周边发现的小煤窑窑口位置相对应。而富水充填的小煤窑采空区表现为低视电阻率异常,经钻探验证,采空区内充填有富含水的粉末状的煤灰,含坑木。需注意在山区进行高密度电法测试时,台阶状的地形对高密度电法测试的干扰影响较大,以温纳装置为例,测试数据在台阶地形处表现为高低阻相邻的八字形干扰,且电极距越小,干扰越明显。

The high density resistivity method has been widely used in coal mine goaf detec- tion. As we know, the different filling materials of the goal results in the different charac- teristics in the 2D apparent resistivity image. Several experiences and cases of using high-- density electrical method to detect shallow goal of small coal mine were mainly introduced in this paper. This company successfully used the high density resistivity method in small coal mine roadway detection of no filling/partly filling in Mentougou district and small coal mine goaf detection of Shijingshan district with the Wenner equipment. The anomalies of roadway of no filling or partly filling appeared as a closed circle with high impedance in the 2D apparent resistivity image. And the positions of anomalies correspond to the small coal mine caves. The anomaly of the small coal mine goal filled with high moisture materials appeared as a circle with low impedance. And the drilling result showed the goal was filled with powdered coal ash and mine timber with high moisture. When using the high density resistivity method on the mountainous area, we found that the step--form terrain would produce a great disturbance to the detection. The dates of the step--form terrain would ap pear as a ＂ ∧ ＂-- shape of interference with adjacent high and low resistance in the 2D ap- parent resistivity image, and the smaller the electrode spacing is, the more serious the in- terference is.