Study On Influence Law Of Stress Release Rate Of Surrounding Rock On Support System In Mountain Tunnel

During the excavation of the tunnel,the stress state around the tunnel is constantly changing.The stress release rate of surrounding rock is closely related to the engineering geological condition,structural design size,construction method and supporting time of tunnel.The stress state of surrounding rock is an important reference index in supporting structure design.Especially,for tunnels with poor geological conditions such as soft rock,the selection of stress release rate of surrounding rock is directly related to the design quality of supporting structure.In this paper,based on the project of Yanchong Expressway tunnel,through field investigation,geological prediction of surrounding rock investigation,displacement monitoring of key points at the tunnel,finite difference software calculation and theoretical analysis,I study on mechanical state and displacement law of surrounding rock and supporting structure in construction process.The main research contents are as follows:(1)Based on the research results at domestic and abroad,the interaction mechanism between surrounding rock and supporting structure is analyzed,and the relationship between stress release rate of surrounding rock and supporting internal force and plastic zone of surrounding rock is analyzed theoretically.(2)The cooperative construction unit adopts the domestic TGP equipment to detect the surrounding rock ahead of the tunnel,and selects the typical forecast results for data analysis,dynamically adjusts the surrounding rock level in the construction process to determine the appropriate supporting parameters;monitors and measures the excavated section,and obtains the surrounding rock by data fitting.Convergence deformation rule,to determine the stability of the tunnel.(3)Based on the field data,through the numerical calculation of FLAC3 D finite difference software,the variation of stress and displacement of surrounding rock with different excavation methods,tunnel burial depth and support parameters under grade IV and V rock conditions is simulated and analyzed firstly;secondly,the stress release theory of surrounding rock is applied to the FLAC3 D calculation model to analyze tunnel burial depth.The influence of stress release rate of surrounding rock on mechanical state of rock,displacement law of surrounding rock,internal force of lining structure and other factors.(4)Based on the static calculation results and the dynamic theory,the seismic wave is debugged and the dynamic module in FLAC3 D is used to analyze the dynamic response of tunnel lining structure under the action of earthquake by using single variable method.