Analysis Of Interaction Between Small-spacing Parallel Shield Tunnel Excavations

With the rapid development of underground traffic, the adjacent construction cases with two or more shield tunnels, and the interaction between shield construction and existing tunnel has become a common and important problem. In recent years, two parallel shield tunnels are widely used in underground engineering, while the relevant theoretical research lags far behind the engineering practice and there is no specific standard in this issue. So, the research of interaction between small-spacing parallel shield tunnels has important theoretical significance and engineering value, and some research works are carried out in this paper on this issue.1. Firstly, the elastic displacement field of soil caused by bulkhead additive thrust and friction force between shield and soil was obtained by using numerical integration based on the Mindlin solution. Secondly, the soil displacement generated by ground loss was solved by using Loganathan’s formula. Then, the total soil deformation induced by shield tunneling was achieved by combining the above three results. Through the disturbed soil displacement was imposed on the existing tunnel and then the equilibrium differential equation of which was established based on Pasternak foundation model, the final internal force and displacement of the existing tunnel caused by shield tunneling was resolved at last.2. The shield tunnel of underpass of North Huancheng Road was simulated in three-dimensional model by using ABAQUS finite element software, with the step excavation, grouting at the tail, and face support process. Firstly, the ground movement, internal force and deformation of segment were obtained by using numerical simulation after the south line was completed. Secondly, considering the construction influence on existing tunnel, the soil displacement and lining response of south line were analyzed during north line construction. Finally, the effect of bulkhead additive thrust and grouting pressure on this project was studied.3. In this paper, relying on the Huancheng Road project, the influence of a new tunnel on a short distance paralleled existing tunnel during shield tunneling has been systematically studied. Data of theoretical analysis, finite element numerical simulation and field monitoring are thoroughly compared and analyzed. The results can be a reference for similar projects in the future.