Construction Technology for Ultra-wide Excavation near Existing Buildings in Metro Station Shield Tunneling Receiving Area

Abstract

Objective It is aimed to address the difficulty in settlement control of existing ground buildings during ultra-large section excavation beneath them in metro station construction. Method Based on the shield tunneling receiving area project of newly built Chengdu Metro Line 18 Nijiaqiao Station, which passes under an existing overpass approach bridge, numerical simulation analysis is conducted to study the construction technology of ultra-wide expansion excavation near existing buildings, and field monitoring data is used for verification. Result & Conclusion The use of advanced pipe-roofing, 12-pilot tunnel segmented expansion excavation, and composite lining construction techniques can effectively control the settlement of existing buildings while enabling long-distance expansion of the main station structure and ensuring the hoisting clearance for shield machine reception. The primary construction steps affecting the settlement deformation of existing buildings are the removal of protective piles and the excavation of ① and ⑦ pilot tunnels. Significant settlement is observed at ① and ④ pilot tunnels, with the maximum settlement value reaching 8.82 mm, which is 1.21 times the maximum settlement value obtained from the simulation. Both the measured and simulated results meet the safety control requirements.

Keywords

• metro station
• shield receiving area
• under-passing buildings
• ultra-wide expansion excavation technology