Research On The Deformation Mechanism And Control Of Tunnel Palm Face Based On ADECO-RS

The deformation control of tunnel face is the core concept of ADECO-RS method construction,but the theoretical research on tunnel face deformation based on ADECORS method is still in the development stage.Therefore,this article is based on the E60 highway tunnel project in Georgia.Through theoretical analysis,numerical simulation,and on-site monitoring,the deformation mechanism of the tunnel face based on ADECORS theory is studied,and a mechanical model and deformation control plan for the extrusion deformation of the tunnel face are proposed.The main research content and achievements of this article are as follows:(1)Based on the theory of ADECO-RS method,the extrusion deformation mechanism of tunnel face was elucidated;On this basis,a mechanical analysis model for extrusion deformation of tunnel face was proposed,and its rationality was verified through numerical simulation;The influence of changes in elastic modulus and Poisson’s ratio on the extrusion deformation of tunnel face was analyzed,and it was found that the elastic modulus has a greater impact on the extrusion deformation of tunnel face.(2)In order to better characterize the process of surrounding rock stress release,the elastic-plastic analysis model of tunnel surrounding rock is established considering the strain softening characteristics of surrounding rock,and the formulae for calculating the range of stress,strain solution and plastic zone of surrounding rock are derived to reveal the composite structural characteristics of surrounding rock;on this basis,the influence of spatial effect on palm face extrusion deformation is studied,and the virtual support force is introduced into the palm face extrusion deformation analysis model proposed in this paper On this basis,the effect of spatial effect on extrusion deformation of palm face is studied,and the virtual support force is introduced into the analysis model of palm face extrusion deformation proposed in this paper.(3)Based on the equivalent reinforcement circle theory,an overrun support deformation control model is established,and according to the location of the plastic zone,the formula for calculating the elastic-plastic deformation of the tunnel envelope under different working conditions is derived,and the characteristic curves of the envelope under different working conditions are obtained,which is used to determine the overrun support reinforcement parameters,and the longitudinal deformation curve of the tunnel is used to determine the overrun support application range,so as to propose a preferred deformation control scheme for the palm face of the E60 highway tunnel in Georgia.(4)Numerical simulation method is used to compare and analyze the proposed preferred solution for palm face deformation control in terms of palm face extrusion deformation,vault convergence deformation and surrounding rock stress,etc.The palm face extrusion deformation is reduced by about 50%,vault convergence deformation is reduced by about 20% and the formation time of arch effect is relatively faster with the overriding support solution compared with the non-overriding support solution.