Anchor bolt is as one of the main supporting forms of rock slope  for underground,plays an important role on stability of civil engineering maintenance, especially it has obvious effect in the joints and fissures in rock mass and anchor rod on rock reinforcement.Anchor bolt is as tension components of deep strata,  one end of it connected to the engineering constructions, the other end in the deep strata, the whole root anchor can be divided into free section and anchor section, free section is put the tension on the top of the bolt to anchor the area of solid, its function is put the prestress on the anchor bolt;Anchorage segment refers to water slurry of prestressed reinforcement and the soil adhesion area, its function is to anchor solid with increase of soil adhesive friction role, increase the pressure on the role of the anchored body,it will put free period of tension to the depths of the soil.

Composed of anchor must have a number of factors:

(1)A tensile strength anchor bolt higher than that of the 

rock rod body and soil mass.

(2)The end of rod body can closely from friction resistance (or bond) with the geotechnical engineering.

(3)The other end of the rod body is located in the external in geotechnical engineering which can form the radial resistance of rock mass.