Technical Analysis of the Removal Techniques for Shield Tunnel Launch and Reception Portals in Subway Construction
To ensure construction safety,the reinforced concrete portals of subway shield tunnel sections need to be demolished or replaced on the steel reinforcement framework before the shield machine's launch or reception.The primary methods include manual pneumatic pick removal,shield machine cutting without prior removal,and mechanical removal.Currently,the most commonly used method is manual pneumatic pick removal;however,it is time-consuming and performed in poor environmental conditions.The cutting without prior removal method involves replacing some of the load-bearing steel bars in the tunnel portal with glass fiber reinforcement,allowing the shield machine's cutterhead to cut directly through them.However,this method requires a specialized design of the shield cutterhead in soft soil conditions.The mechanical removal method is a middle-ground approach,offering high efficiency,environmental friendliness,and safety.Through comparative analysis,the applicability and cost-effectiveness of the three methods are assessed,providing a reference for future subway construction.
shield tunnel portalmanual removalcutting without prior removalmechanical removal
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