瞬变电磁勘探技术在探测采空区中的应用——以阳煤集团氧化铝厂采空区勘探为例

瞬变电磁法(TEM),是利用不接地回线向地下发送一次脉冲瞬变磁场,再测定一次脉冲瞬变磁场引起的二次涡流场的方法。当地下存在电性不均匀体时,会观测到电性不均匀体的涡流异常场,通过对异常场的分析研究,推断矿体、地下水、采空区等地下盲体的存在和部位。华北石炭-二叠煤系地层的电阻率比非煤系地层的电阻率值高,铝土矿层电阻率相对较低,下伏奥陶系灰岩电阻率最高。地下矿体局部被采出后,对应地层的导电性随采空区的塌陷程度及赋水情况不同,表现为相对较高的电阻率或较低的电阻率值,依据此特征成功地利用瞬变电法应用于采空区探测中。

Application of TEM on exploration of subsurface mined areas——An example of application in alumina producer of coal company in Yangquan

Transient Electromagnetic Method(TEM) is a reconnoitre method by sending out a pulse transient magnetic field toward underground using the loop not connecting ground,and then measuring again quadric backsets that is caused by the change of the magnetic field.When an asymmetrical electric body exists,an abnormal field of the backsets will be detected.By analysing and researching the abnormal field,the existence and the position of the underground blind body,such asgroundwater,mineral body and mined-out area can be predicted.The resistivity of Carboniferous and Permian coal is greater than that of non-coal stratum in North China,and the resistivity of the bauxite layer is relatively lower,and the resistivity of nether Ordovician limestone is the largest.After the part of the underground mineral body is mined,the conductivity of the corresponding stratum will be different with the degree of sinking and the circumstance dampness penetration and its resistivity will be raising or descending.By the above characteristic,the authors explored the mined-out area are successfully.