A Study On Mechanical Behaviors And Fireproof Methods Of Tunnel Lining Structure During And After Fire Scenarios

It is an important concern to protect tunnel lining structure from fire in tunnel fire prevention engineering. Numerous cases on tunnel fires emphasized the importance of fire protection of tunnel lining and indicated that fire may cause severe damages to tunnel lining in term of concrete spalling, reduction of physical-mechanical characteristics and load bearing capacity. As the number of traffic tunnels under construction increases, how to improve fire safety of tunnel lining structure becomes a key issue in the whole process of tunnel design, construction and operation.Mechanical behaviors, fireproof capacity and vulnerable spot of tunnel lining structure are studied in this paper at three levels i.e. material, structural element and structural system. The contents involve: 1) fire scenario and its design method used in fire prevention design of tunnel lining structure; 2) mechanical characteristics of shield tunnel segment include reinforced concrete segment (RC segment) and steel fiber reinforced concrete segment (SFRC segment) during and after different fire scenarios; 3) mechanical characteristics of shield tunnel joint include reinforced concrete joint (RC joint) and steel fiber reinforced concrete joint (SFRC joint) during and after different fire scenarios; 4) mechanical characteristics of shield tunnel ring include reinforced concrete ring (RC ring) and steel fiber reinforced concrete ring (SFRC ring) during and after different fire scenarios; 5) fireproof methods to protect tunnel lining structure from fire.On the basis of fire experiments, theoretical analysis and FEM simulation, a series of valuable findings are achieved in this paper: 1) Complete fire scenario composed of temperature-time curve, transverse temperature distribution and longitudinal temperature distribution and the design method are established with consideration of tunnel fire characteristic and its influencing factors. 2) Analytical method of temperature distribution in tunnel lining structure is presented. Moreover, according to tunnel fire behaviors, thermal boundary condition and concrete spalling,...