ABSTRACT
The major difference between double-deck tunnels and general tunnels is the existence of middle slab in double-deck tunnels. Both sides of the middle slab lie on the brackets along the longitudinal direction and the bearing pads between slab and bracket may need to be replaced for maintenance. In this case, part of the middle slab needs to be lifted for the replacement of the bearing pads. The objective of this study is to evaluate slab lifting strategies of the middle slab in double-deck tunnel when replacement of bearing pads lying between slab and bracket is needed. The middle slabs have been divided into three different sections as normal, expansion joint, and emergency passageway sections. At each section, several different slab lifting methods have been applied and analyzed to investigate the stress distribution in the slab and to evaluate the maximum tensile stresses. The analysis results show that the optimal slab lifting method that reduces the maximum tensile stresses of the slab is different depending on the section type of the middle slab.
