地电阻率测量中电极埋深影响的数值模拟研究

Numerical Simulation on the Effect of Apparent Resistivity from Different Depth of Electrode Layout

结合测区的地质水文资料,采用有限元分析软件ANSYS对河源和平地电台地区建立三维有限元物理模型并进行物理环境变化下的数值模拟实验,并分别计算了正常状态、地表雨水、挖土施工、地下低阻流体四种情况下真电阻率的变化对观测电阻率的影响,在四种情况下模拟分析不同的电极埋深对电阻率观测值的影响。结果表明:电极埋深越深,对表层电阻率变化越不敏感,而对深层环境变化反映越明显;相反,电极埋深越浅,越容易受到表层环境的干扰,而对深层有意义的变化却反映迟钝。

Acoording to the hydrological and geological data of the measurement area, a three-dimensional finite element mode was constructed to simulate Heping geoelectric station and analyze the effect of physical environment on apparent resistivity from different depth of electrode layout. The paper simulates the impact of the resistivity change to the apparent resistivity in the case of the normal state, the surface precipitation, the construction of digging and the underground low resistivity fluid respectively. Under the four situation, the paper analyzes the impact of the apparent resistivity by the different depth of electrode layout. The results show that the deeper the electrode layout, the apparent resistivity is more interfered by the deep environment and less sensitive to the ground-surface conditions; to the contrary, the shallower the electrode layout, the apparent resistivity is more robust to the ground conditions but less sensitive to the deep environment.