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Abstract Based on the construction of a shallow-buried tunnel in Beijing metro，the constraint effect of pilot-drift and separation-pile structure on ground movements induced by shallow tunneling is analysed. Restricted by the surface environment of construction area，two pilot-drifts with small cross-section and shotcrete linings were constructed above each side of the subway running tunnel，and reinforced concrete piles were installed in the ground below the drifts to separate the negative effects of tunnel construction on the two high-rise buildings located nearby at each side of the tunnel，respectively. Based on the mechanisms of the pilot-drift and separation-pile structure，a simplified analytical model is formulated to estimate the deformation of structure and ground，and a three-dimensional elasto-plastic finite element model is constructed to simulate the tunneling sequence and its effects on surrounding environment. The comparison between the modeling results and in-situ monitoring data is conducted，and the key factors affecting the performance of the pilot-drift and separation-pile structure are summarized.
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Received: 10 March 2003
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