Abstract:
Objective When new shield tunnels cross under existing operational subway tunnels, settlement will be induced, further affecting the safety of the existing operational tunnels. Current researches predominantly focus on predicting and controlling the ground settlement induced by shield tunneling underneath existing roads, tunnels, or buildings. In contrast, there are relative less studies on the settlement prediction of twin shield tunnels undercrossing an existing operational tunnel track. Therefore, it is necessary to conduct an in-depth research on it.
Method Based on the engineering background of Hefei Metro Line 2 Eastern Extension’s new tunnel, which crosses beneath the existing operational Line 2 tunnel in close-range, a PSO (particle swarm optimization)-SVM (support vector machine) prediction model is established, and the PSO-SVM model dynamic prediction flow is introduced. The model is trained based on the monitoring data collected from nine typical monitoring sections, and the settlement value induced by the new tunnel undercrossing the existing operational tunnel is dynamically predicted.
Result & Conclusion Based on the PSO-SVM prediction model, the average value of prediction result errors across various monitoring sections is 8.31%, further verifying the feasibility of the PSO-SVM model for dynamic prediction.
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