EXPERIMENTAL STUDY ON ENERGY RESPONSE OF ARGILLACEOUS SANDSTONE UNDER CYCLIC LOADING

At present, the application of energy principle to study the failure, deformation and stability of rock mass is the focus of rock mechanics research. This paper aims to study the response laws of three kinds of energy of argillaceous sandstone. They are the volumetric energy per unit, the volumetric elastic energy per unit and the volumetric dissipated energy per unit under cyclic loading. The loading and unloading test is carried out considering different frequencies, confining pressures and stress amplitudes. The test results show that the three kinds of energy response to number of cycles have the same performance with different pressures and same frequency. With the increase of frequency, the three kinds of energy response laws to number of cycles show regular volatility. Performance among accumulated volumetric energy, accumulated volumetric elastic energy and number of cycles is approximately linear. The accumulated volumetric dissipated energy is strongly characterized by nonlinearity. The energy rate index is used to measure the degree of energy change. The higher the frequency, the greater the change of the energy rate. There are sudden change points in the curve of volumetric dissipated energy rate versus time, preliminary speculated to be the threshold point for the development of cracks in the inner or surface of the rock sample. Through the analysis of the factors affecting dissipated energy, we can find that the positive increasing trends are shown among confining pressure, frequency, dynamic stress amplitude and dissipated energy respectively. Based on the analysis results of relevant literatures, three kinds of energy response laws are comprehensively analyzed from the beginning of the cycle to the final failure of the rock. The energy response laws of the rock sample under cyclic loading are clarified. It is helpful to deepen the understanding of the energy response law, damage and failure of argillaceous sandstone, and provide experimental basis and application guidance for analyzing the stability of rock mass engineering using energy principle.