砂土的电化学阻抗特性及其试验研究

Experimental Study on Electrochemical Impedance Characteristics of Sand

通过电化学工作站测试了不同颗粒尺寸、不同含水量砂土体系的电化学阻抗谱图,利用Z-View软件拟合与解析其等效电路,分析电路参数与颗粒尺寸、不同含水量的变化关系,并研究了各个参数之间的相互关系。结果表明:砂土的电化学阻抗谱呈准Randles模型,其等效电路元件包括:孔隙溶液电阻、固-液界面电容、电荷转移电阻、扩散阻抗。Bode图中阻抗模值随着频率、含水量及颗粒尺寸的增大呈下降趋势;当含水量相同时,孔隙溶液电阻基本相同,随着颗粒尺寸的增大,固-液界面电容呈增大趋势,电荷转移电阻、Warburg扩散系数呈减小趋势;当颗粒尺寸相同时,随着含水量的增大,固-液界面电容呈增大趋势,孔隙溶液电阻、Warburg扩散系数呈减小趋势。研究结果对电化学阻抗谱理论在岩土工程性质方面的应用与研究提供新的思路与技术。

The method of electrochemical impedance spectroscopy （EIS） can be applied to study structural characteristics of sand which consists of sand particle and pore solution. The EIS diagrams of Bode and Nyquist, equivalent circuit of the whole sand system with different particle size and water content are studied and analyzed by using CS350 electrochemical workstation. The results show that the EIS of sand presents pre-Randles model and its equivalent circuit components include pore solution resistance, solid-liquid interface capacitance, charge transfer resistance anddiffusion impedance. The modulus of impedance in Bode diagram decreases with the increase of testing frequency, particle size and water content of sand. When water content is kept con- stant, the pore solution resistance tends to keep constant while solid-liquid interface capacitance increases, the charge transfer resistance and Warburg diffusion coefficients decrease with the increase of particle size. When the particle size is kept constant, pore solution resistance increases while solid-liquid interface capacitance and Warburg diffusion coefficients decrease with the increase of water content. The concluding research results are expected to broaden applications of EIS methods in geotechnical engineering.