Dingli Zhang

Protection of buildings against damages as a result of adjacent large-span tunneling in shallowly buried soft ground

Lot JC3 of the Xianmen Airport Highway Project in China involved building a twin-tube tunnel with each tube serving three-lane one-way traffic. The existence of 79 overlying buildings brought great challenges to the tunnel construction. To safeguard these buildings, two building blocks located above the nearby tunnel portal were approved by the owner of the project to be the trial blocks. Compensation grouting was adopted for ground settlement compensation at this lot. Free-field compensation grouting tests were conducted to derive the suitable grouting parameters. Pretreatment to reinforce the ground prior to the tunneling passage, concurrent grouting to compensate the excessive settlements during the tunneling passage, and regrouting to uplift the distorted buildings after the tunneling passage were designed to protect the trial blocks. According to the monitoring data of the trial blocks and the ground, the characteristics of the soil-structure interaction were studied and the criteria for the safety of the structures were therefore determined.

Structural Responses of Secondary Lining of High-Speed Railway Tunnel Excavated in Loess Ground

To systematically study the mechanical properties and structural responses of the secondary lining for high-speed railway tunnels excavated in loess ground, on-site monitoring was performed to measure the contact pressure between the primary lining and secondary lining. It is found that the contact pressure reaches its first peak value when the tunnel formwork carriage is removed. The load acting on secondary lining is in the form of deformation pressure, which is different from the loose pressure prescribed in the China Tunnel Design Standard. The results obtained from this study enhance our understanding towards the mechanical characteristics of secondary lining for high-speed railway tunnels and are also beneficial to secondary lining design.