Effect of unloading behavior on stress wave transmission in a double-scale discontinuous rock mass

AbstractStress wave propagation through double-scale discontinuous rock masses considering unloading behavior was investigated. The piecewise linear loading and unloading models of macrojoint were proposed, which were combined with a split three-characteristics mothed to investigate the stress wave transmission properties. The effects of the waveform, frequency, amplitude and propagation distance on the energy and amplitude transmission coefficients were discussed. The results of the present study were compared with the traditional study that considered single-scale discontinuities. The results show that the present study can effectively analyze the effect of the waveform, frequency, amplitude and propagation distance on the energy and amplitude transmission coefficients. The energy and amplitude transmission coefficients for rectangular wave are the largest, while those for triangular wave are the smallest. The energy and amplitude transmission coefficients decrease as frequency and propagation distance increase. The energy and amplitude transmission coefficients increase as the amplitude increase. The results also show that the effect of macrojoint unloading effect and microdefect on wave transmission can be considered comprehensively in the present study. The unloading effect of macrojoint causes the smaller energy transmission coefficient, while it does not affect the amplitude transmission coefficient. The microdefects cause smaller energy and amplitude transmission coefficients.Highlights The effect of unloading behavior on wave propagation in rock mass was studied.The piecewise linear loading and unloading models of macrojoint were proposed.Macrojoint and microdefect in rock mass were considered in a framework.Energy and amplitude transmission coefficients were studied in present study.KEYWORDS: Unloading behaviorwave transmissionrock massmacrojointmicrodefect AcknowledgementsThis work is supported by the National Natural Science Foundation of China [grand no. 12172019] and Beijing Natural Science Foundation [grand no. JQ20039].Disclosure statementNo potential conflict of interest was reported by the author(s).