Enhancing the bearing capacity of friction anchor bolts through cementitious concrete injection for reinforced support in underground mine

Friction anchor bolts are commonly used for providing support in underground structures by relying on frictional forces between the bolt and the surrounding rock. This study proposes a method to enhance the efficiency of these bolts by injecting a cement-based mixture comprising cement, sand, and additives. The injection of this mixture into the bolt results in internal expansion, which reinforces the friction and bearing capacity of the bolt. The increased volume exerts a radial force, leading to improved adherence, load transfer, and void filling. Pullout tests were conducted on various rock masses to evaluate the performance of the anchor bolts. The results demonstrate increased pullout resistance with higher rock mass quality and longer cemented bolts. Additionally, the use of a silicate-based additive accelerated the curing time of the cement, enhancing the strength of the bolts. The study also highlights the significant influence of groundwater on the bearing capacity of the bolts. These findings indicate the effectiveness of cemented concrete injection in strengthening friction anchor bolts and their anchorage in underground structures.