Mechanical Research and Optimization of the Design of an Umbrella-Shaped Enlarged-Head Hollow Grouting Bolt with an Expansion Pipe

In geotechnical engineering, traditional anchor bolts often have problems such as an insufficient bearing capacity, their ease of loosening, and an unsatisfactory support effect under complex geological conditions (such as soft soil or broken surrounding rock), resulting in it being difficult to guarantee engineering stability. In order to solve these problems, this paper studies the supporting performance of a hollow grouting anchor with an umbrella-shaped expansion head with an expansion pipe. Through theoretical analysis, mechanical performance analysis, and experimental analysis, the supporting mechanisms and mechanical characteristics of a hollow grouting anchor with an umbrella-shaped expansion head are systematically discussed. The calculation formula for the maximum pull-out force of the umbrella-shaped expansion head is clarified, and the fixed range of the expansion body section in relation to the loose ring is quantified. Based on the analysis results, the structural parameters and material properties of the bolt were optimized, and the optimization effect was verified by numerical simulation. The results show that the optimized bolt has significantly improved the pull-out bearing capacity, shear resistance, and reinforcement effect on the soil. The maximum pull-out force of the umbrella-shaped expansion head can be increased by up to 35%, and the fixed range of the expansion body section can be expanded by 45%. The research provides an efficient and reliable support solution for geotechnical engineering fields, such as roadway engineering and tunnel engineering, which significantly improves the stability and safety of engineering under complex geological conditions. At the same time, it provides an important theoretical basis and practical reference for the design and construction of similar projects.