Electrical resistivity-specific parameters of loess grouted with sodium hydroxide

In order to study the reinforcement mechanism of the single fluid alkalization method and to consider the possibility of using the permeation variation of loess, direct shear tests of loess were performed before and after the strengthening process of single fluid alkalization, and the resistivity of loess was measured. The test results indicate that the shear strength of alkaline loess samples is significantly higher than those without alkaline, due to a series of physical and chemical reactions occurring after the injection of lye. With the increase of the electrical current frequency, the vertical and horizontal resistivities of loess decrease quickly at first and then become stable. When the electrical current frequency is below 50 kHz, even a slight change of the current frequency will greatly affect the measured resistivity values of loess. When the electrical current frequency is above 50 kHz, the resistivity of loess seems no longer be affected by the current frequency. The vertical resistivity and the horizontal resistivity decrease with increasing curing time and finally remain stable during the single fluid alkalization process, in which the decreasing trend occurs in the initial stage. The average formation factor and the average shape factor decrease with increasing curing time and become stable eventually. The electrical anisotropy index increases rapidly with increasing curing time at first and eventually stabilizes. All tests indicate that during such single fluid alkalization process the use of the resistivity procedure to study the loess structure changes is an effective method.