Stress state monitoring of rock mass using acoustic emission effects in anisotropic comosite materials
Possibility of using acoustic emission memory effect in anisotropic composite materials for evaluation of stress-strain state of rock mass is shown. The analysis of laboratory research results of common and specially synthesized materials is performed. It was found that the angle between direction of uniaxial compression application and direction of lamination (elastic inclusion plane for synthesized material) in composites has a significant impact on the behavior of acoustic emission during the first loading cycle, and manifestation of acoustic emission memory effect. Thus the lowest values of the acoustic emission activity are when such angle is 90° in the first loading cycle. When studying memory effect it is manifested most clearly at an angle of 0° for synthetic materials with elastic inclusion and 45° for layered composites. A method that allows continuous monitoring of maximum principal stress orientation acting in the area of excavation is offered. Also a method for determining direction and magnitude of increments of the maximum principal stress, based on memory effects in some anisotropic composite materials is provided