Research On Macro And Meso Shear Characteristics And Damage Of Anchored Jointed Rock Mass

The rock mass undergoes a long period of geological tectonic movement and natural corrosion and exploitation to form its complex structure and structure,which contains various faults,shear zones,joints,cracks and other defects.The existing defects of the rock mass directly affect the mechanical properties of the rock mass,and then control its engineering geological characteristics.When engineering construction encounters such rock masses,it is bound to affect the safety of the engineering construction and the later service life.Therefore,it is necessary to strengthen the jointed rock mass.Among them,anchor bolt anchoring is widely used in engineering practice.In this paper,the anchored jointed rock mass is taken as the research object,and the shear mechanical properties of the anchored jointed rock mass under different working conditions are studied by using macro indoor shear test,meso-CT scanning test,and macro-meso damage composite evolution model.The main conclusions are:?1?The shear strength at the joint inclination angle of 45ois the largest,and the strengths at the inclination angles of 60oand 30oare similar.The law of the shear strength changes with the joint inclination angle is:?_45°>?_60°>?_30°>?_0°;The shear strength is the largest,and the law of shear strength with joint roughness is:?_JRC=16>?_JRC=21>?_JRC=9>?_JRC=3>?_JRC=0;?2?By comparing and analyzing the rock masses with and without anchors,the shear strength and stiffness of the rock masses with anchors are greater than the rock masses with no anchors and the shear strength-displacement of the rock masses with anchors The curve is"double hump";the anchors play a pin and restraint function when the jointed rock mass is subjected to shearing,which can improve the shear strength of the jointed rock mass and effectively control the deformation of the jointed rock mass;?3?The images obtained by CT scanning are processed by means of gray processing,image denoising,edge detection,and threshold segmentation.The same fault is selected to calculate different joint inclination angles,joint roughness,and crack rates in different states.The comparison shows that with the change of joint dip angle,the total fracture increase of the rock mass has a negative correlation with the change trend of its peak strength.With the change of joint roughness,the total fracture increase of the rock mass and its peak strength have a negative correlation.The change trend is negatively correlated;?4?Three-dimensional reconstruction of the processed CT image to obtain reconstructed rock masses under different conditions such as different joint inclination angles,joint roughness,and different states.The reconstructed rock masses are obtained from the fractal dimension and volume.Calculate and study the density and gray value,and analyze the correlation between shear strength and fractal dimension,volume density and gray value,and there is a high correlation between them.Internal ruptures provide new directions;?5?Analyze the anchors in the anchored jointed rock mass to obtain the shear strength formula of the anchored jointed rock mass under the action of shear load;combine the macro and meso damage theory,and use the porosity The volume fraction is the damage description parameter to derive the composite model of macro-meso damage of anchored jointed rock mass.