Relationship of Resistivity with Water Content and Fissures of Unsaturated Expansive Soils

The development of fissures in expansive soils has a great effect on the stability of slope. Of the three phases of soils, the gas phase and solid phase are relatively insulated, so the average resistivity of soils can be calculated from the resistivity of the liquid phase. On this basis, the two-part model of resistivity changing with the water saturation of the expansive soil can be deduced. A 2-D resistance grid model is established based on simulating the resistance of vertically developed fissures. Variation in measured resistance of vertically developed fissures at different positions can be calculated from this model. Fissure development can be inversely determined from the variation in the measured resistance. Finally, the model is verified by an indoor resistivity test for remolded soil samples, indicating that the test result agrees well with that of the model established.