Experimental Study on the Entropy Change Failure Precursors of Marble under Different Stress Paths

다국어 초록 (Multilingual Abstract)

In this paper, the indoor loading and unloading tests and acoustic emission (AE) monitoring tests of marble under different stress paths are carried out. Based on the AE events in the process of rock failure, this paper introduces the concept of information entropy of Shannon, and defines a new cumulative state information entropy which can characterize the degree of disorder and accumulation of rock microcracks. This paper also offers a comparative analysis on the evolution law of rock entropy under different paths and different loading and unloading conditions. The results show that the newly defined cumulative state information entropy can well reflect the order change of the loading and unloading process system, and there are significant differences in entropy evolution under different stress paths, but the entropy generally evolves with the development of the system from “quasi-equilibrium” to “far away from equilibrium”. The higher the unloading level is, the greater the confining pressure is, the stronger the unloading disturbance is, and the entropy value drops sharply at the starting point of unloading. The faster the unloading rate is, the later the rock fracture instability is, and the later the entropy drop point of the system appears. The change rate of entropy value |ΔH|= 0.1 can be used as the precursory signal threshold of rock confining pressure unloading disturbance damage and peak rupture instability.