Shield machine disassembly in grouted soils outside the ventilation shaft: A case history in Taipei Rapid Transit System (TRTS)

During the construction of the ventilation shaft A of the Luzhou Line of Taipei Rapid Transit System (TRTS), the shield machine obliged to disassemble in grouted soils outside the shaft as the excavations in the shaft were still in progress. This paper describes the use of ground improvement followed by cement and chemical grouting as well as dewatering to both reduce the water ingress to acceptable volumes and the piezometric pressures in an alluvial silty sand layer during the shield disassembly task. In addition, the chamber sealing and bulkhead installation were designed to prevent the tunnels and shaft from any accident through which the tunnel would subsequently pass.