Shield-driven induced ground surface and Ming Dynasty city wall settlement of Xi'an metro

摘要

The influence of metro shield construction in congested urban areas on nearby buildings is of great concern in practice. In this study, 3D-FEM model, validated through comparison with field monitoring results were used to investigate the influence of Xi'an Metro Line 4 excavation on existing city wall of the Ming Dynasty at Heping Gate in loess ground. The research results were found to be in good agreement with field measurement results. Furthermore, the results indicated that because of pre-reinforcement by sleeve valve pipe grouting and supporting by I-shaped steel at openings, the surface settlement within the foundation area on the city wall is reduced by 4 mm compared with that without the reinforcement, and the settlement of the city wall structure is reduced by approximately 2.2 mm, which prevents excessive local heave of the city wall foundation and out-oflimit of inclination. Additionally, the settlement-time curves of the city wall structure and change laws of surface settlement slot were also obtained. This study provides a valid reference value for protecting historical buildings adjacent shield construction in similar loess areas.