Investigation and Analysis of Fiber Concrete Lining of Tunnel Opening Under the Effect of Thermal Load

Examining the thermal behavior of concrete lining of tunnels against thermal loads is of special practical importance. The purpose of this research is to investigate the behavior of fiber concrete lining tunnels with rectangular, semicircular and horseshoe sections under the effect of thermal load in a specific time history. In this regard, numerical simulations have been carried out using Abaqus finite element software. Stress-time and deformation-time graphs in fiber concrete coating under the effect of thermal loads have been investigated. Fiber concrete in this research, which is considered as cover in tunnel sections, is of steel fiber concrete type with a volume percentage of 0.5 to 1.5. Also, in addition to the common design loads, the sections are subjected to thermal loading conditions. According to the obtained results, the strength of the investigated sections depends on the amount of steel fibers in the concrete in addition to the appearance. Investigations show that the cross-section with horseshoe shape has the best performance against thermal load and the increase of fibers up to 1.5 volume percent of concrete compared to tunnel linings with a lower volume percentage of fibers leads to stability in a longer period of time.