Comparative Analysis of Anti-skid Performance of Smooth and Studded Gripper Shoes for Hard Rock TBMs in Steeply Inclined Shafts

Abstract

Pumped-storage hydropower is a key clean energy source for grid stability and emergency backup. Tunnel Boring Machines (TBMs) enable safe, automated, and efficient hard-rock excavation with minimal environmental disturbance. To mitigate the critical risk of tunnel boring machine (TBM) slippage and subsequent retrograde falling in steeply inclined shafts, this purely numerical study presents a comparative analysis of the anti-skid performance and mechanical mechanisms of smooth versus studded gripper shoes. Comprehensive multi-body finite element simulation models, coupling the high-strength aluminum alloy (7075-T6) gripper shoe structural matrix with various surrounding rock classes, were developed using HyperMesh and LS-DYNA software. The structural response and anti-skid capacities of both configurations were systematically evaluated under distinct rock conditions, with a specific focus on the potential plastic deformation of the anti-skid studs. The numerical results indicate that under a conservative baseline friction coefficient of 0.3, the anti-skid capacity of the studded gripper shoes in Class II and Class III surrounding rocks increases by 18.5% and 12.1%, respectively, compared to the smooth configuration. This mechanical enhancement is primarily attributed to the additional plowing resistance generated as the studs penetrate the rock mass. Furthermore, the maximum equivalent stresses induced during the full penetration and subsequent shearing displacement within both Class II and Class III rock matrices do not exceed the yield strength of the stud material, demonstrating that structural integrity is maintained without local plastic failure. These findings demonstrate that the optimized lightweight studded gripper configuration significantly enhances gripping stability while minimizing the dead-weight of heavy tunneling apparatus. Cultivating these mechanical insights provides valuable design guidelines and a scalable safety strategy for TBM selection, risk mitigation, and operational safety control in high-inclination underground excavation projects.