What is the role of ring erection in segmental lining installation?

Ring erection is a critical step in segmental lining installation. It involves the precise placement and assembly of precast concrete or steel segments to form a complete, continuous ring that provides structural support to the tunnel. The primary role of ring erection is to create a stable and load-bearing tunnel lining that can withstand the earth and water pressures acting on the tunnel. The segments are typically erected using a segment erector, a mechanical arm or crane that is part of the TBM. The erector picks up individual segments and positions them against the tunnel wall. The segments are then connected to each other using bolts, dowels, or other connecting devices. The accuracy of ring erection is crucial for ensuring the structural integrity of the tunnel lining. Misaligned or poorly connected segments can create stress concentrations and weaken the lining. The geometry of the segments and the design of the connecting devices are carefully engineered to ensure a tight and secure fit. Grout is often injected behind the segments to fill any voids between the lining and the surrounding ground, providing additional support and preventing water inflow. The ring erection process is typically automated to improve efficiency and accuracy. Sensors and control systems are used to monitor the position and alignment of the segments. The term 'segmental lining' refers to a tunnel lining that is constructed from precast segments. 'Ring' refers to a complete circular section of the tunnel lining. 'Segment erector' is the machine that is used to lift, position, and install the segments. 'Grout' is a pumpable material used to fill voids and stabilize the ground.