Abstract: Based on the interaction mechanism among the surrounding rock-shield-grouting-lining segments during the construction of tunnels using the shield tunnel boring machine (TBM) method, utilizing a longitudinal deformation curve of the surrounding rock that accounts for the interaction with the shield-surrounding rock, in conjunction with the Drucker-Prager yield criterion, we propose a method for calculating the surrounding rock pressure in deep-buried tunnels constructed using the shield TBM method, considering the interactions among the surrounding rock-shield-grouting-lining segments. The proposed method is compared with field-measured data and results from other surrounding rock pressure calculation formulas. Research shows that the surrounding rock pressure in Shield TBM tunnels primarily manifests as deformation pressure. The calculated surrounding rock pressure values using the deformation pressure formula, which considers the interactions among the surrounding rock-shield-grouting-lining segments, show better agreement with field-measured data compared to other formulas based on loose pressure. The surrounding rock pressure is influenced by factors such as the properties of the surrounding rock, tunnel depth, cutter-head overcut, shield length, and grouting timing. The surrounding rock pressure initially increases and then decreases with the increase in rock cohesion. It shows a similar trend with the increase in the internal friction angle of the surrounding rock. The surrounding rock pressure decreases with the increase in the elastic modulus of the surrounding rock and increases with the increase in tunnel depth. It decreases as the cutter-head overcut increases, as the shield length increases, and as the delay in grouting behind the shield tail increases. When the surrounding rock interacts with the grouting and lining segments, a larger initial displacement released by the surrounding rock results in smaller surrounding rock pressure on the structure. The proposed surrounding rock pressure calculation method provides valuable guidance for the structural design of deep-buried TBM tunnels.

Key words: shield TBM, deep-buried tunnel, Drucker-Prager yield model, longitudinal deformation curve, rock-shield-grouting- lining interaction, surrounding rock pressure, deformation pressure