Study Of Control Of Double Shield TBM Jamming By Numerical Simulation In Deep Squeezing Ground

TBM has the advantages of construction safety,rapidity,and environmental protection,which is widely applied in the world.However,large squeezing deformation frequently occurs easily when TBM tunneling through deep soft ground under high in-suit stress,once the deformation of surrounding rock exceeds the overcut,it will squeeze the TBM shield,and finally leading to TBM jamming easily which will cause serious lost.Therefore,in order to explore reasonable control measures for the control of double-shield TBM jamming,using 3DEC to establish a numerical model,studding the impact of advance rate,overcut,lateral pressure coefficient,parameters of backfilling material,backfill thickness and soft filling length on the control of double-shielded TBM.The main research contents and results are the following:(1)Considering the surface effect of the tunnel and the rheological properties of the surrounding rock,the interaction model of the surrounding rock-TBM was constructed using the built in CVISC viscoelastic plastic constitutive model of 3DEC,and the excavation process of double-shielded TBM was simulated by the dynamic distribution excavation method.(2)Using the above numerical model,the influence rules of changes in advance rate and overcut on the deformation of surrounding rock,TBM contact pressure,and total TBM resistance were analyzed,and the effect on the state of the TBM jamming and the permissible downtime of the TBM were confirmed finally.Increasing the advance rate and enlarging the overcut are effective control measures for the TBM jamming;at the same time,there are inflection point values for the advance rate and overcut during the study,and the control of TBM jamming effect is more obvious at the inflection point value.(3)The influences of lateral pressure coefficient,deformation parameters of backfill materials,backfill thickness and soft filling length on the deformation of surrounding rock,the total contact pressure of TBM and the total resistance of TBM were discussed,and the results show that the larger lateral pressure coefficient is the more adverse to the control of TBM jamming;the greater elastic modulus of backfill layer is more favorable to total stability of the tunnel;increasing the thickness of the backfill layer will facilitate the control of the TBM jamming with an increasement of construction cost,so the thickness of the backfill layer should be reasonably selected according to the practical project;increasing the soft backfill length will increase the probability of the TBM jamming.