Analysis On Lateral Impact Of Songjiazhuang Subway Station Pit Construction's Model On Adjacent Station In Operation

As China's economic development, automobile ownership surges in major cities. The crowded ground transportation appeals to urgent need to develop subway traffic. With steadily improvement of subway transit network, more and more transfer stations will be built. The excavation pit of new subway station will inevitably close to the original station. While the excavation around the foundation causing the water table and stress field change, these changes are bound to have some impact on the existing station. Therefore, how to ensure the safe operation of the existing subway station in the construction of pit excavation has become an urgent problem to be solved.This thesis takes Beijing Subway Line 10 Songjiazhuang Station excavation project as study object. Using FLAC3D program to perform three-dimensional numerical simulation of excavation and combined with on-site monitoring data analysis, a preliminary study has been made about the effect of lateral displacement produced by the excavation on the adjacent station in operation.First of all, horizontal displacement of pile, soil lateral deformation, retaining structures deformation, groundwater level, ground subsidence, and level-vertical displacement deformation on roof-floor of the Songjiazhuang Station have been observed and recorded. Combined with the characteristics of this project, monitoring data of floor-roof horizontal displacement of original station and horizontal displacement of excavation pit wall north of the station are analyzed. The displacement rule of roof-floor and pit in line 5 during excavation has been drawn.Then, the numerical simulation has been made on the completed parts of 10th Line Songjiazhuang excavation pit. During the excavation, the displacement and speed of north side of retaining wall that support the original station has been studied and analyzed. Comparative analysis is made between numerical simulation results and value of on-site monitoring to validate the correctness of numerical simulation model and parameter selection.Finally, for the impact of excavation method, excavation layer thickness, and original subway station of the 5th line Songjiazhuang's lateral effect, based on the principle of spatial effect, eight different working conditions have been differentiated and three-dimensional numerical simulation of excavation has been performed. Through the analysis of retaining wall displacement field north of the station and node represents the horizontal displacement, rules of excavation method, excavation layer thickness and block mode on the impact of the north retaining wall have been concluded. And the best construction methods are put forward to prevent subway station in operation from having a greater lateral movement on this basis.