Abstract: Aimed at the mechanism analysis of the “S” type joints in the fractured rock mass，a numerical simulation of the anchoring effect of joint is made.Through numerical simulation software FLAC^3D，a fractured rock mass model under single and double root is built to simulate the mechanical properties of the fractured rock mass under different anchor grouting method and compare their anchoring effect and the main failure mode.The results showed that：anchoring can effectively improve the mechanical parameters of the fractured rock mass，such as its strength and elastic modulus，and increase the overall mechanical properties of rock mass.Different ways of anchor injection has different anchoring effect on fractured rock mass.After “S”-type fractured rock mass is anchored，its stress concentration phenomenon can be alleviated，and the peak of tensile stress also falls.The bolt anchoring effect is better to install the bolt at the end of fracture than in central crack，especially in the peak strength and elastic modulus with bigger difference，and it presents better effect at the end of fracture anchor bolt after peak strength，and has good inhibition on later extension of crack.The study provides a theoretical basis for anchoring this type of fractured rock.

Key words: Numerical simulation, Anchor reinforcement, Fractured rock mass with the type of “S&rdquo, Anchoring effect