Mechanism and Application of Pre-stressed Grouting Bolt with Constant Resistance and Large Deformation

To study the mechanical properties and its application of the pre-stressed grouting bolt with constant resistance and large deformation (PGBCRLD), the cavity expansion theory and other related mechanical methods were used to calculate and develop the constitutive equation of the grouting bolt. Meanwhile, bolt supporting resistance, tensile deformation and support effect were analyzed and verified by the pull-out test and field practice. The results indicated that properties of the bolt cone end and the strength of surrounding rock were the main factors which influence the support effect of bolts. And when the value of drawing force was more than 220 kN and constant in the pull-out test, the elongating of grouting bolt was up to 75–80% higher than the common one, and good support resistance was maintained. Therefore, the design of grouting structure could control large deformation of surrounding rock effectively, soft rock in particular, and provided a tool to effective control of disaster accidents in coal mine.