Mechanism of Isolating Piles in Reducing Tunnel Settlement of Hong Kong-Zhuhai-Macao Bridge Project

Abstract

Artificial islands are adopted in Hong Kong-Zhuhai-Macao Bridge (HZMB) project to form the transition between the bridges and tunnels. A transition foundation solution along the longitudinal direction is introduced, including cast in place piles and PHC piles. Large area of backfill at both sides of the tunnel structure can result in unacceptable settlement as well as differential settlements along the transverse direction. Several measures have been suggested in the real project to deal with this problem, including increasing the length of piles underneath the tunnel structure, and adding two rows of isolating piles at both sides. These treatments are systematically introduced in this paper and a 3-D soil-structure interaction finite element analysis is also carried out which thoroughly models the construction steps. Mechanism of isolating piles in reducing tunnel settlement and uneven settlement is investigated. The study outcome provides reference for similar immersed tunnel projects.