Study On Crack Evolution And Mechanical Mechanism Of Anchored Rock Mass

The interior of the engineering rock mass contains a large number of holes,cracks and other defects.Their existence seriously reduces the carrying capacity of the engineering rock mass.In order to extend the life of engineering rock mass and increase the strength of engineering rock mass,rock and earth engineering has applied anchor reinforcement technology to improve the structure integrity of rock mass and give full play to the carrying capacity of rock mass.Although bolt reinforcement technology has been applied to engineering practice for more than a century,the Anchorage mechanism of bolt has not been fully understood in this paper,the fracture evolution and mechanical mechanism of Anchorage fissure rock mass are systematically studied through experiments.The research results are as follows:(1)According to the research contents,a new experimental die was designed to accurately preset the cracks and accurately locate the angle between the cracks in the bolt.The materials needed for brittle and ductile experiments were selected through material ratio experiments.(2)Displacement meter and AE system monitoring show that there is no deformation in front and back of the specimens without anchorage cracks,and the deformation range of left and right sides is 3 mm to 10 mm.From the beginning of loading to the final failure,the deformation of the specimens with anchorage cracks is 50% higher than that of the specimens without anchorage cracks.Compared with the non-anchored specimens,the anchored rock mass specimens have stronger acoustic emission signals in the residual strength section,while the cement mortar acoustic emission signals are weaker than gypsum.(3)Under uniaxial compression,the stress-strain curves of the specimens of the two materials exhibit double-peak characteristics,and the compressive strength of the specimens anchored with gypsum increases significantly.The minimum value is obtained when the stress is β=60°,but it is still 1.92 times that of the non-anchored state.The compressive strength of the cement mortar specimens has little change,even less than that of the non-anchored state when the stress is β=30°.The elastic modulus and residual strength of the specimens anchored with gypsum and cement mortar have the same change trend.With the increase of beta angle,the elastic modulus decreases first and then increases,and the minimum value is at β=60°.(4)The initial crack of wing crack in anchored and non-anchored crack specimens is a general rule.With the increase of angle beta between anchored control surface and crack,the initial crack angle decreases first and then increases.Five types of cracks are defined in the research process.The order of initiation is wing crack,anti-wing crack,secondary coplanar crack,secondary inclined crack and far-field crack.Five kinds of crack penetration modes were summarized by studying the evolution of cracks in two kinds of materials under uniaxial loading.The paper has shown in 95 figures,19 tables and 130 references...