| The shield tunnel may be hindered by established structures when it was built in the center of the city. How to maintain the security of the structures and to decrease influence to the environment near becomes the focus and difficulties for the subway system. Previous studies shown the common way was to remove the bridges of underpin the piles or pile foundation underpinning. However, it not only results in great waste but also brings the traffic terrific effect. Therefore, it is necessary to investigate this problem further.In this study, the security of earth pressure balance shield cutting Guangji Bridge pile foundation is evaluate qualitatively and quantitatively using theoretical analysis and calculation, based on the data of14piles of the Guangji Bridge form project Su Zhou Metroline2. Meanwhile, the security of tunnel lining structure is forecast by modified routine method. Finally, the deformation law of the pile after the shield pass crossing the strengthened bridge pile foundation is simulated by MIDAS/GTS software. The main results and conclusions in this study can be drawn as follows:(1) By investigating and comparing successful cases domestic cutting pile foundations with shield machine with this project, the results shown that it’s feasible to cut pile foundations of GuangJi bridge in Su Zhou, while it may exist risk due to many uncertain factors.(2) Based on the evaluation of influence of the bearing capacity and stability of the bridge after pile foundations by shield machine cutting from whole section, the results shown that bearing stratum of pier1doesn’t satisfy requirements, and it needs to reinforce foundation and ground of bridge.(3) By analyzing and calculate the stress state of the linings with the modified routine method, the conclusion is the type of shield segment should be ultra-deep from the aspect of safety.(4) Using the finite element method to evaluate the influence of the structure and reinforcement of the bridge by the shield construction, we make the conclusions:both the bridge and the runnel are safe with the shield construction.(5) The some measures in this study were proposed to keep the safety, such as improving the shield, the construction control and the risk response.In this study, the results shown it’s feasible to cut the piles directly, and it provide a new way to cut the piles, and it will give the experience for the similar project in the future. |
