Experimental Study On Mechanical Anisotropy Of Irregular Columnar Jointed Rock Mass

Columnar joint structure is a kind of complex primary tensile fracture structure.Due to the complexity of its joint network,the destruction of columnar joint rock mass is uncertain,which causes many problems for engineering construction.In order to study the mechanical characteristics of columnar jointed rock masses,this paper uses laboratory model tests and discrete element numerical analysis to study the failure modes and anisotropic characteristics of irregular columnar jointed rock masses.The main research results are as follows:(1)A random simulation method for irregular columnar joints based on Voronoi diagrams is proposed.The simulated irregular columnar joints are similar to the geometric characteristics of natural columnar joints,and the 400 typical exposed columnar jointed rock bodies surveyed on site are taken as the example verifies the feasibility of the method.(2)The uniaxial compression test method is used to study the failure mode of irregular columnar jointed rock specimens with different column inclination angles to study the failure mode.The results show that the irregular columnar jointed rock specimens with different column inclination angles have Three typical failure modes.At the same time,it is found that the strength and deformation modulus of the irregular columnar joint rock mass show obvious anisotropy,that is: in the range of ?=0°?90°,the uniaxial compressive strength and deformation modulus of the irregular columnar joint rock mass The change trend of the volume with the inclination angle of the column is approximately a "J" curve.(3)Factors such as the joint network density and regularity of the joint network of the columnar jointed rock mass will affect the uniaxial compressive strength of the columnar jointed rock mass,which in turn affects the anisotropic characteristics of the columnar jointed rock mass.Among them,the greater the density of the columnar joint network,the lower its compressive strength,the more obvious the anisotropic characteristics.The worse the regularity of the columnar joint network,the lower its compressive strength and the more obvious the anisotropic characteristics.(4)The lateral strain ratio of irregular columnar jointed rock mass also exhibits anisotropic characteristics.In the range of ? = 0 ° ? 90 °,the lateral strain ratio of irregular columnar jointed rock mass shows an approximate trend with the change of column dip angle "M" type,and put forward an empirical prediction formula for lateral strain ratio of irregular columnar joint rock mass.