Experimental Investigation of Nonlinear Energy Evolution and Failure Characteristics of Granite under Different Water Content States

Abstract

To study the energy evolution law and failure characteristics of granite under different water content states, a series of compression failure tests of dry, natural, and saturated granite samples under different confining pressures were carried out based on the RMT-150B rock mechanics test system. The research results show that the compressive strength, cohesion, and internal friction angle of granite samples decrease to different degrees with increased water content. The growth rate of the total input energy and elastic strain energy of granite samples in the energy evolution process decreases with increased water content. The higher the water content of granite samples, the lower the total input energy, the slower the elastic strain energy rises, the lower the energy storage limitation, the earlier the dissipation energy starts to increase rapidly, and the lower the final energy dissipated. Based on the principle of self-repression of energy, a nonlinear model and its mathematical equations for the energy evolution of granite are established. The higher the water content of granite samples, the greater the energy iterative growth factor and its increasing rate, and the lower the deviator stress level of granite sample systems entering the period-doubling bifurcation and chaos areas. The samples show three failure modes: splitting failure, splitting-shear composite failure, and shear failure. The failure modes of granite samples have an excellent matching relationship with the distribution range of its energy storage limitation. When the energy storage limitation of the samples is minor, it is more likely to occur splitting failure. When the energy storage limitation of the samples is significant, it is more likely to occur shear failure.