Acoustic Emission Characteristics of Ice-Rock Mixture and Frozen Soil-Rock Mixture under Splitting Test

Research on frozen geotechnical material is focused on guaranteeing the security of civil engineering and preventing of geological hazards in cold regions. The acoustic emission (AE) tests of the ice, ice-rock mixture, frozen soil, and frozen soil-rock mixture samples were carried out under Brazilian splitting conditions. The characteristics of crack evolution, acoustic emission energy and, b-value were discussed. The results show that: (1) The cracks in the ice-rock mixture and frozen soil-rock mixture are more tortuous than those in ice and frozen soil. (2) The crack in the ice-rock mixture is mainly distributed inside the ice near the ice-rock interface. Moreover, the tensile strength and acoustic emission energy of the ice-rock mixture are larger than that of ice. (3) The crack of frozen soil-rock mixture is composed of frozen soil crack and soil-rock interface crack. The frozen soil-rock interface is the weakest part inside the frozen soil-rock mixture, which leads to the acoustic emission energy of the frozen soil-rock mixture is smaller than that of frozen soil. (4) The acoustic emission energy peak of ice and ice-rock mixture being consistent with the leading peak and shows an obvious single peak pattern. Nevertheless, in the case of frozen soil and frozen soil-rock mixture, the acoustic emission energy peak lags behind the loading peak and display a multi-peak feature. (5) The b-values of all the samples decrease with the increasing loading in the pre-peak region, and then show an increasing trend with the decreasing loading in the post-peak region. Furthermore, the amplitude of the b-value of frozen soil-rock mixture is larger than that of others. It can be postulated that the alternating crack growth of soil and interface cracks triggers the different acoustic emission energy.