Drawing Characteristics And Numerical Analysis In Wholly Grouted Anchor Base On Couple Stress Theory

The technology of bolt anchoring is widely used in slope, tunnels and mines and other fields. The bolt anchoring itself is very diversity and is impacted by geographical environment, rock and soil types and distribution area and other factors. So, the bolt anchoring mechanism and design theory are not perfect. Shear stress distribution in anchorage interface of anchor is the attention points of anchor design. It directly affects anchoring effect. Shear stress in anchorage interface will cause larger strain gradient in rock and soil near anchorage interface. The strain gradient is not considered in classical elastic theory which can’t explain the phenomena of bending deformation and failure in the anchoring section. Bending curvature is introduced into couple stress theory which considers the effect on the deformation characteristics of the bending.Finite element analysis program of couple stress theory was wrote base on MATLAB, which was combined with the basic equations of couple stress theory and finite element method. The correctness of the program was verified through the simple cantilever operator.The finite element model of plane strain was established base on couple stress theory. The fully bonded was used to research interface shear stress distribution, boundary layer effect and scale effect. The results of couple stress theory were compared with the results of classical elasticity theory. The results show that the shear stress and shear strain near anchorage interface in couple stress theory are smaller than that in classical theory, especially at the peak of shear stress. The shear stress on interface is not continuous. But shear strain abrupt change on interface has been improved and a transition region appears near the interface.The Mechanical Characteristics of anchoring interface was researched on characteristic length, shear modulus, modulus of elasticity of rock and soil and confining pressure.The results show that the impact of characteristic length to anchor interface shear stress was obvious, as the characteristic length decreases, the transition region becomes smaller, while the strain gradient increases. The impact of second shear modulus to shear stress distribution was not obvious. As the rock more softly elastic modulus is smaller, the maximum shear stress and axial force are smaller; conversely, the harder Rock, the greater the elastic modulus, The shear stress and axial force are greater. As the greater the confining pressure, the anchor shear stress and axial force are significantly reduced, especially at the peak of scale effect.