基于围岩成拱理论的TBM掘进最小覆岩厚度理论模型与数值模拟研究OA

Based on the surrounding rock arching and hinge-less arch structure theories,a theoretical formula for the mini-mum overburden thickness was derived.By substituting dif-ferent mechanical parameters of multiple tunnels at home and abroad into this formula,minimum self-supporting arch for-mulas under different surrounding rock classes were ob-tained.Based on the actual engineering case of a dual-mode shield tunnel,a numerical model for the tunnel boring ma-chine excavation mode was established to verify the theoreti-cal formulas.Next,three surrounding rock classes,four soil layer thickness gradients,and twelve overburden thickness gradients were designed,resulting in 144 models formed by the combination of the three factors.Uniform tests were con-ducted,and the pressure arch heights under different sur-rounding rock classes were obtained.The results show that in the theoretical formulas,the tunnel radius has a linear posi-tive correlation with the pressure arch height,while the tun-nel depth has a linear positive correlation with the square of the pressure arch height.According to numerical simulation results,the pressure arch height increases with the increase of the overburden thickness and then tends toward a critical value of twice the tunnel diameter.Finally,the results of the numerical model are in good agreement with those calculated using the theoretical formulas,verifying the rationality of the established theoretical formulas.