Stability Analysis And Risk Assessment Of Shallow Large Span Metro Station Constructions

Large span metro station with Shallow Mining Method has the characteristics of shallow depth, large excavation section, poor surrounding rock stability and complex construction technology, the slightest mistake would cause too much ground deformation or even collapse. Additionally, the metro station is generally located below urban road with heavy traffic, where surrounded buildings are everywhere, underground pipelines cloud, geological conditions are complex. All these risk factors make tunnel construction more easily endanger the safety of the people and the environment around it and cause serious social impact and economic losses.In this paper, Qingdao Metro Line 3 shallow excavation large span subway station-Qingjiang Road Station is taken as research background. Through three-dimensional numerical experiments, variations of rock displacement field, rock stress field and plastic zone of rock sections during tunnel construction under different excavation methods and different support measures at different levels, is comparatively analyzed. Based on the analysis above, the preferred construction method of put forward.Through analyzing the scene monitoring measurement data, deformation characteristics of tunnel surrounding rock and force conditions of support measures are obtained. Rock grades are dynamically corrected based on the excavation uncovered rock condition.Based on monitoring measurement and correction of surrounding rock grades, three-dimensional numerical simulation of the entire process of Qingjiang Road Station construction is carried on, variation of first displacement and extrusion deformation of the working face, the scope of the plastic zone in front of the working face and force characteristic primary support are comprehensively analyzed.On the basis of monitoring measurement data and numerical simulation results, combined with engineering geological conditions and the surrounding environment of Qingjiang Road Station, risk factors during construction are identified, estimated, and then dynamically assessed by AHP,obtaining the dynamic risk rating of Qingjiang Road Station construction, and make the necessary responses to the significant risk factors.