Influence of different boundary constraints on bearing characteristics of anchorage section of bolt

Abstract

In order to study the influence of different boundary constraints on the bearing characteristics of the bolt anchorage section, the stress conditions of the bolt in the state of tension bearing and bolt-surrounding rock coordinated deformation bearing state were analyzed, and the numerical calculation with different boundary constraints was carried out. The research results show that the axial force of the bolt decreases along the anchorage length under different boundary constraints, and the attenuation speed is faster under lateral constraints. Under the condition of top fixed and lateral restraint, the axial force of the bolt decreases at 1/2 of the anchorage length, obviously slows down and approaches to zero. The axial force of the bottom fixed lateral restraint bolt decreases slowly within 5 cm of the anchorage beginning, and then decreases in a power function. Under the condition of top fixed and lateral restraint, the shear stress peak of the bolt-anchorage agent interface appears at 2 cm of the outer end of the anchorage, while under the condition of bottom fixed and lateral restraint, the shear stress peak is at 9-10 cm of the anchorage depth. Under the condition of top fixed and lateral restraint, the peak shear stress of anchorage agent-surrounding rock interface is located at the outer end of anchorage, and the peak shear stress under the condition of bottom fixed lateral restraint is located at 8 cm outside the anchorage. The magnitude and location of the shear stress peak value of the two interfaces are different, which is the important influencing factor of various anchorage failure modes.

Keywords

• coal roadway bolt
• anchorage section
• bearing characteristics
• boundary constraint
• numerical computation