Analysis Of Friction Resistance And Shield Jamming Of Tbm In Deep And Long Tunnel Considering Complicated Mechanical Effects Of Rock Mass

With the increase in the construction of deep long circular tunnels,the research related to the TBM advancing technology becomes more significant gradually.Based on the mechanical behavior of the rock after the peak,this dissertation studies the rock deformation of the circular tunnel by the two-dimensional analysis.Afterthat,the theory is extended to the three-dimensional space for investigating TBM tunneling friction resistance and the jamming accident.Firstly,based on the stress stratified model,combined with the critical value of the plastic softening coefficient,the Hoek-Brown yield criterion,and the Mohr-Coulomb yield criterion,a numerical solution for the strain-softened surrounding rock deformation of circular tunnel is obtained.Its rationality is verified by a calculation example and FLAC3 D numerical simulation.The influence of the critical value of plastic softening coefficient and rock mass dilatancy characteristic on the radial displacement of surrounding rock was analyzed.The results show that under the same conditions,the deformation values obtained using the elastic-brittle-plastic,strain-softening,and elastic-perfectly-plastic models decrease in order,and the strain softening model is a unified model;in soft rock,the dilatancy characteristic makes the deformation of the surrounding rock increasing more significantly.Secondly,based on the confined convergence method,considering the post-peak mechanical behavior of rock,combined with the non-linear dilatancy characteristic and the downtime,a theoretical solution of TBM driving friction resistance was proposed,and its rationality is verified.In addition,a new model for predicting TBM jamming accident is summarized.Then,taking the over-excavation gap into consideration,relevant discussions are carried out.The results show that the better the quality of the rock mass is,the less prone the jamming disaster is;for strain-softened surrounding rocks,the judgment of the jamming disaster requires detailed calculation and cannot be generalized.Finally,combined with the GSI rock mass classification system,the calculation method of the TBM driving friction resistance is optimized.According to the strength parameter formulas of the Hoek-Brown criterion under the GSI system,and taking the strain-softened surrounding rock into consideration,the influence of five factors on the friction resistance of the TBM is analyzed.The results show that: in terms of the analysis of shield-related parameters,only the shield length has significant effect on the friction resistance;the larger the over-excavation is,the frictional resistance decreases rapidly at first,and then reduce slightly;the frictional resistance increases at the beginning of the shutdown,and the value keeps constant after that.