Research purposes: Nowadays shield machine is widely used in metro construction. However, the much loss in stratum may occur during shield tunnelling and too much loss in stratum may cause big-scaled surface subsidence, resulting in bad impact on the ground buildings and underground pipelines, even damaging them with big economic loss. Taking the Line 1 of Nanjing Metro as an example, the site tests are done for the displacements of buildings and underground pipelines and changes of underwater level during shield tunnelling, and through making analyses of them, the regularities of impact on the surrounding environment are obtained. Considering the relations between stratum subsidence and soil pressure in soil chamber and between synchronous grouting volume and discharging waste soil volume, the discussion is made on the preventive measures for control of stratum subsidence.
Research methods: The site tests are done for the displacements of buildings and underground pipelines and changes of underwater level during shield tunnelling and through making analyses of these tested data, the valuable conclusion is obtained for reference to construction.
Research conclusions：Modification and right choice of the parameters for shield tunnelling, keeping effective balance of soil pressures and ensuring the effect of synchronous grouting are the effective means and important measures for control of the loss in stratum and reduction of displacement of stratum and impact of shield tunnelling on the surrounding environment.
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