Abstract
Deformation and rupture of rock mass under loading cause the variation of electric potential. Response characteristics of self-potential and stress during the complete stress-strain process of red sandstones play an important role in evaluating the stress state of sandstone on the basis of self-potential. Experimental results demonstrate that the stress of red sandstone under uniaxial compression is linearly correlated with the self-potential difference before the first inflection point in the initial stage of loading. The average variation rate of self-potential difference and stress is 0.1325 mV MPa−1. As the loading pressure gradually increases and enters the softening stage (before the maximum loading point), the catastrophic points of uniaxial loading stress correspond to the inflection point of self-potential. The self-potential of red sandstone varies in a range of 0–45.6 mV in that case and it fluctuates most significantly around the maximum loading point, with a range of 0.3–195.5 mV. In the end stage of loading, the macroscopic rupture of the red sandstone sample is complete, the self-potential of red sandstone fluctuates slightly around the maximum load point and then gradually stabilizes. Moreover, it is found that self-potentials change more significantly in the radial direction than in the axial direction in the uniaxial compression experiment, indicating that self-potentials generated by rock mass rupture are more sensitive in the radial direction. The rupture process of red sandstone can be dynamically represented by the tempo-spatial evolution profiles of self-potential.
Analysis of Self-Potential Response beyond the Fixed Geometry Technique
