人文干扰对电法勘探的影响及应对措施

Influence of human interference on application of electrical prospecting and corresponding anti-interference measures

在我国中东部地区,特别是矿区及其外围,电磁干扰十分严重,试验表明,这些干扰在时间上全天候存在,无规律可循;在空间上分布范围广,达数千米以上,无法避让;频谱特征复杂,除50 Hz及其谐波外,高、中、低全频段均有干扰。这些干扰影响电法勘探数据质量,降低电法的勘探深度,处理不当会产生假异常,误导验证工程,给电法勘探工作造成极大困难。对此可采用老资料的二次开发、矿区停电或错时(利用矿区检修等停工间隙)观测、窄带数字滤波和新型抗干扰电法仪器测量等措施获取有效资料,这些措施在危机矿山找矿专项、老矿山找矿项目中均有成功的应用实例。

The electromagnetic interference is very serious in the eastern region, Chinaespecially in the mining area and its pe- riphery. Experiment results show that the interference occurrs all the time and no apparent rules can be found. It is widely distributed which can extend up to several kilometers, and can not be avoided. The interference has complex spectrum characteristics which in- cludes full frequency bands except the 50Hz frequence and its harmonic. These interferences cause great difficulties for the application of electrical prospecting. Neither qualified data could be obtained nor effective exploration depth could be ensured. Even worsely, if the data could not processed properly, we may get false anomaly that would mislead engineering verification. In this paper, we summarize some anti-interference measures which can help eliminating the electromagnetic interference and obtaining valid data such as collecting and reprocessing the historical data, observing during the power cut by using narrow band digital filtering and observing with new anti- interference electrical instrument. These measures were successfully used in the special project of Ore Deposit Prospecting in National Exhausted Mine and Old Mine.