时/频域激电参数在铬污染模拟场地探测中的应用

在低供电频率(2-4、2-2、20、22、24 Hz)范围内,利用研发的时/频域测量系统,在室外铬污染模拟场地进行时/频域激电探测,实测视电阻率、视极化率、相角,结合最小二乘反演算法,研究各参数对铬污染低阻异常区域及其对铬浓度(以w计)差的体现. 结果显示,视电阻率和视极化率随着铬浓度差的增加而迅速减小,视电阻率从背景值的80 Ω·m左右减至50 Ω·m以下,视极化率从背景值3.0%~3.8%减至0.6%~2.2%；在不同的供电频率下,相角对含水率和铬浓度差的体现有所差异. 试验数据还显示,当供电频率从2-4 Hz增至24 Hz时,实测相角数值较为平均,但是经过最小二乘反演后,相角上限从6.27°减至1.75°. 研究结果说明,单纯的时域参数(视电阻率和视极化率)很难区分含水率和铬浓度差引起的低阻异常,但供电频率在2-2~20 Hz范围内时,频域参数相角可以区分含水率和铬浓度差引起的低阻异常. 

Time-Frequency Domain Induced Polarization Parameters Applied on Chromium Pollution Simulation Survey Site

This research studied the effects of time-frequency domain induced polarization applied on a chromium pollution simulation site survey. Combined with the least squares inversion algorithm, resistivity, polarizability and phase angle can be measured by time-frequency domain IP measurements to research the phenomenon of various parameters on chromium contamination of low resistivity anomaly area and concentration differences of chromium (using w as the abbreviation) pollution within low frequency ranges (2-4, 2-2, 20,22,24 Hz). Resistivity and polarization decreased fast as w (chromium) increased. Resistivity decreased from 80 Ω·m to 50 Ω·m or less and polarizability was reduced from 3.0%-3.8% to 0.6%-2.2%. At different frequencies, the phase angle reflected differently in water content and w(chromium). Experimental data showed that as the supply frequency increased from 2-4 Hz to 24 Hz, the measured phase angle values were more even. However, after the data were processed through the least squares inversion, the phase angle was reduced from 6.27° to 1.75°. The results show that the pure time-domain parameters (resistivity and polarizability) are difficult to distinguish the low-resistivity anomaly caused by moisture content or concentration differences of chromium. However, if supply frequency is within the range of 2-2-20 Hz, frequency-domain parameters (phase angle) can distinguish the different concentrations of chromium contamination, which causes low resistivity anomaly.