Abstract: Water is one of the main factors that induce mine disasters. Monitoring methods for disasters caused by mine water can be extended by studying the charge induction signal of rock deformation and failure under the interaction between water and rock. In order to study the effect of water content on the charge induced signal in the process of rock deformation and failure, we derive an electrostatic-mechanical coupling model based on the damage theory, and obtain the theoretical relationship among the amount of induced charge, the rock mechanical damage and the water-induced damage. Using the self-developed charge-induced signal acquisition system, we carried out the uniaxial compressional charge-induced signal monitoring on the rock samples with different water contents. We analyze the effects of water on the mechanical properties of rock, as well as on the charge induced signal in each stage of rock failure process, and discuss the mechanism by which water content affects the generation of induced charges. The results show that: (1) The charge induced signal in the process of rock deformation and failure is related to the damage degree of rock. The ratio of the cumulative induced charge to the total induced charge can indicate the damage level of the rock under the action of water and force. The higher the content of water is, the easier the samples that can generate a large number of charge-induced signals under lower stress. (2) The macroscopic failure characteristics of rock samples are obviously different with different water content. With the increase of water content, the compressive strength of rock samples decrease, the cracks develop, and the failure mode of the rock samples changes from single shear failure to tension and shear mixed failure. (3) In terms of the distribution of the charge-induced signal, the increase of water content increases the number of high-amplitude charge clusters, and makes them developed into the elastic stage. The high-amplitude charge-induced signals are mainly distributed in the late elastic stage and the plastic stage. (4) Considering the amount of induced charge, with the increase of water content, the proportion of induced charge released in the elastic stage gradually increases, whereas the proportion gradually decreases in the plastic stage. The amount of induced charge in the elastic and plastic stages accounts for more than 90% of the total amount of induced charge generated in the rock deformation and failure process. (5) Water weakens the rock particles and osmotic pressure, through which it makes the rock produce or expand cracks under low stress, and therefore the induced charge signals can be more abundant.

Key words: moisture content, charge induced signal, damage, force-electric coupling model, cumulative induced charge