Abstract: In the study of early warning of backfill instability, the acoustic emission precursory characteristics have been recognized by many scholars. However, there are many forms of acoustic emission precursory characteristics, which have certain influence on the early warning of the backfill instability. Based on this, this paper attempts to establish a fixed form of early warning model of the backfill instability. First of all, based on the energy evolution characteristics and cusp catastrophe theory, an early warning model of backfill instability is constructed, and then the uniaxial compression acoustic emission verification test is carried out for backfill with different ash sand ratios. Experimental results show that the early warning state of backfill can be described by the interval composed of the catastrophe of dissipative energy and the catastrophe of releasable elastic strain energy, and the interval is defined as early warning interval. Moreover, the early warning intervals of backfill with different cement-sand ratios are unique, implying the model is extremely flexible and universal. The precursory characteristics of acoustic emission characteristic parameters with high recognition such as ringing counting rate are employed to verify the reasonableness of the early warning interval. It is found that the early warning interval calculated from the model is highly consistent with the time of the precursory characteristics of acoustic emission parameters, further proving the rationality and universality of this model and providing a new idea for the early warning of instability of backfill.

Key words: early warning model, cusp catastrophe theory, precursory characteristics of acoustic, emission energy evolution