非饱和红黏土受压过程中的电阻率特性及其模型试验研究

A theoretical model and measurements of resistivity of unsaturated laterite under compression

文章从现有的三相介质导电模型出发,假定非饱和黏性土存在四种电流导电路径,理论推导得出非饱和黏性土的三维电阻率模型。基于改进的土体固结压缩电阻率测试装置,探讨了红黏土受压过程中的饱和度、孔隙率及电阻率特性的变化规律,结合红黏土的电阻率测试结果对理论模型进行验证,构建未受压、受压情况下的非饱和红黏土三维电阻率模型。结果表明:在连续分级荷载作用下,红黏土电阻率及其结构特性参数(结构因子F、形状因子f以及各向异性系数A)随着荷载的逐渐增大呈现出减小趋势,当荷载较大时电阻率变化不明显;在红黏土压缩过程中,伴随着孔隙率的减小,饱和度逐渐增大,且电阻率随着饱和度的增大而逐渐减小;采用三元相图分析了非饱和红黏土三维受压导电模型的可靠性,该模型能较好的揭示荷载作用下红黏土电阻率的演化过程。可为以红黏土为建筑材料的碾压工程压实度评价提供理论模型,有利于拓展高密度电阻率法在碾压工程质量检测、监测及其评价方面的应用研究。

A three-dimensional resistivity model of unsaturated laterite was derived based on an existing three-phase porous media conductivity model,assuming four kinds of current conduction paths in unsaturated clays.An oedometer was improved to measure the degree of saturation,porosity and resistivity of the laterite during compression.The proposed model was verified by the test results.The results show that the resistivity of laterite decreases with the increasing loading,but the decreasing rate becomes small under greater loads.The degree of saturation gradually increases with the decreasing porosity,which also leads to decrease of resistivity.A ternary phase diagram was also used to examine the reliability of the proposed model and indicated that this model can well simulate the evolution of laterite resistivity under monotonic loading.