Research on the measurement of interfacial polarization voltage by the extrapolation method
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摘要: 界面极化电压的测量对提高隧道掘进机(TBM)中BEAM电法前探的灵敏度具有一定的实用价值,而岩土与护盾电极之间的界面极化电压用传统方法难以精确测量.为此,本文提出一种界面极化电压的外推测量方法.该方法由一个样品筒和若干等距分布的电极构成,在样品筒两端施加交流电,测量各电极的交流复电压,根据电极之间的几何关系即可外推得到两端供电电极的界面电压.实验结果表明,该方法能够准确测出泥状岩土与金属电极之间的界面极化电压,且当泥状岩土中含有木炭或水洞等异物时,可以先用该方法测出泥状岩土与护盾电极之间的界面极化电压,然后将其在电法超前探测的总电压中扣除,从而提高隧道超前探测的灵敏度.Abstract: It is of practical value to measure the interfacial polarization voltage for improving the sensitivity of BEAM advanced detection method used in TBM tunnel.However,it is difficult for conventional methods to measure the interfacial voltage between solid rock mass and electrode accurately.In order to measure the interfacial voltage,the authors propose an extrapolation measurement method in this paper.The proposed method consists of a sample tube and a number of equally spaced electrodes.Sinusoidal alternating current is exerted on both sides of the sample tube.The AC complex voltages of every electrode are measured.According to the geometrical relationship between the electrodes,the interface voltage of the two power supply electrodes can be obtained by extrapolation.Experimental results indicate that the interfacial polarization voltage between clay and metal electrode can be successfully measured by the proposed method.When abnormal body such as charcoal or water hole exists in the sample tube,the polarization rate change of the measured rock-soil can be greatly raised by subtracting the interfacial polarization voltage from the total voltage.Therefore,the sensitivity of tunnel advance detection can be improved by this method.
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