Memory bearing: A novel solution to protect element joints from differential settlement for immersed tunnels with deep alignment

Abstract

Abstract The immersed tunnel in the Hong Kong–Zhuhai–Macao Bridge (HZMB) project has a deep alignment and poor geological conditions; the soft soil layer is up to 30-m thick. To protect the structure of the element joints of the immersed tunnel from differential settlement, we developed a special type of bearing that can be placed between the vertical shear keys of the element joints. These bearings ‘remember’ the maximum capacity that the tunnel structure can undertake so that they can guide the force flow from overloads via the tunnel structure to the foundation in the most appropriate manner to protect the shear-transferring structure while fully utilising it. As of now, all the element joints of the thirty-three elements in the HZMB tunnel are being protected with the bearings installed. This paper elaborates on our concept and experiments, based on which our design and applications were carried out.