Influences of tunnelling parameters in tunnel boring machine on stress and displacement characteristics of surrounding rocks

During the operation of a tunnel boring machine (TBM), the stress and displacement of the surrounding rock are closely related to the tunnelling parameters, and the judicious selection of these parameters is crucial for improving TBM’s tunnelling efficiency and equipment utilisation. This study uses finite-element software to develop a three-dimensional mechanical model of a TBM cutterhead and the surrounding rock under the combined action of thrust and torque. It simulates the impact of TBM tunnelling construction on the tunnel’s surrounding rock excavation. Through numerical simulation, the relationship and influence of the TBM tunnelling parameters under various surrounding rock conditions are investigated, as well as the distribution characteristics and laws of the surrounding rock stress and displacement near the tunnel face under different thrust and torque conditions and the mechanical behaviour of the TBM cutterhead regarding the front overall surrounding rock. The results indicated that the influence of thrust change on the surrounding rock is significantly greater than that of torque change, which is minimal and can be ignored. The influence range of thrust and torque under class-A surrounding rock is within 1 m of the tunnel face, and under class-B surrounding rock is within 2 m of the tunnel face. The surrounding rock stress and displacement are closely related to the surrounding rock classification: the higher the quality and integrity of the surrounding rock, the lower the surrounding rock stress and displacement, thereby maximising the surrounding rock’s self-supporting ability.