Abstract：The basic laws of electrical conduction by ions for rocks and the measuring methods of pulse non-polarization for electrical current are studied. The theoretical relation between the rate of electrical resistance and that of porosity for rocks is explained. The study on the electrical effects of limestone and sandstone containing NaCl solution under compressive stress is presented with the method of combining mechanics and electricity. The experimental facility is established and the complete experimental data of stress-strain-electrical resistance of rocks are achieved. The experimental results indicate that the electrical resistance variation of rock fluctuates with the variation of the internal fissures of rock. There is a minimum value for electrical resistance of rock in all electrical resistance-strain curves，by which the cracking stress of rocks can be justified and defined. In the process of rock fracture，there is a clear anti-symmetry between the change law of stress-strain curve and that of electrical resistance. Based on the experimental study and the stochastic property analysis of rock fracture variation，the equations of stress-strain-electrical resistance in sections are proposed with a new distinguishing feature，by which the regular stress of rocks and the remnant stress can be described. The complicated fracture characteristic of rocks can also be displayed clearly by the electrical resistance of rocks. It further verifies the associated state equations with rock compression through fitting the calculated results of the experimental data for limestone and sandstone，which can be used to reveal the evolution laws of rock fracture.
