Research On Ground Settlement Deformation Of Large-Span Underground Excavated Tunnel In Qingdao Metro

During the construction of urban rail transit, the subway station is located in the intersection of multiple complex surrounding environment, part of the station cannot but constructed by undermining method, affected by the factors such as the flow path and moving of Pipeline. The subway station is shallow, above the poor geological conditions, the excavation method often leads to the top surface settlement is too large, serious will lead to pipeline rupture, road collapse, the tunnel collapse. the Qingdao subway station construction processes, the majority were exceed the standard phenomenon of ground surface settlement, additional construction and management difficulty,leading to the construction of the extension of time. Metro Line 3 is Qingdao’s first subway line construction,experience less, for provides some guidance for the design, construction and risk control on subsequent lines, settlement deformation rules and control criteria for the analysis of this paper focuses on the 3 line of large span excavation surface.1. Shallow buried tunnel surface subsidence deformation mechanism were reviewed, including the mechanism of settlement, settlement mechanism,formation damage caused by soil excavation theory.2. Shallow buried tunnel surface subsidence deformation mechanism were reviewed, including the mechanism of deformation caused by excavation, settlement mechanism, and the soil loss theory.3. Summary the main construction method of Qingdao subway station of large span tunnel, and analyzes main influencing factors of ground settlement, including engineering geology, groundwater,engineering management, tunnel abdominal span ratio, and puts forward some control measures, including strata pre-reinforcement, the reasonable construction method, construction organization and management.4. Analysis of when the large span excavation station on both sides of the drift excavations, the surface settlement is generally relatively small, is less than-10mm, for middle or pilot tunnel excavation will produce bigger surface subsidence,according to differences in geological conditions,large settlement of up to-30 mm above.5. The station excavation deformation of ground surface settlement curve fitting process, found that the use of a three order polynomial fitting effect is good, the correlation coefficient was above 0.95, but also can be seen, a formula for the number of changes in the surface subsidence curve fitting of the difference is large, the universality of the poor.6. Analysis of large span tunnel of Qingdao subway station surface subsidence deformation difference is bigger, but the individual station still has some rules to follow, such as zhanshan station and wannianquan Road station basically conforms to the Peck surface settlement trough, the fushansuo station and junfeng Road station is at the top of the sinking type belongs to the whole, Zhongshan Park station and Qingjiang Road station on both sides of the station heading above the surface subsidence above the centerline, was W.