AUTHOR=Liu Cong , Wu Bo , Li Rui , Wang Feng , Tang Qianlong 

TITLE=Fatigue Test on Heavy Haul Railway Tunnel Bottom Structure With Base Cavity

JOURNAL=Frontiers in Earth Science

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2022.870710

DOI=10.3389/feart.2022.870710

ISSN=2296-6463

ABSTRACT=<p>The presence of a base cavity will degrade the bearing capacity of tunnel bottom structures, and will also have a noteworthy impact on its fatigue performance. In order to study the fatigue performance and cumulative damage to tunnel bottom structure, a series of bending fatigue tests are conducted by reference to a heavy haul railway tunnel with a base cavity. Through the tests, fatigue evolution characteristics of tunnel bottom structure with cavity are obtained, then based on the expression of <italic>S</italic>-<italic>N</italic> curves, a non-linear fatigue cumulative damage model is therefore proposed, the deflection evolution and cumulative damage evolution can be divided into three stages, and characterized with an “s-shaped” curve. The tests results reveal that the damage to the tunnel bottom structure develops rapidly when a cavity exists in the base rock, fatigue occurs more easily, and the fatigue life of specimens decreases with the increase of the stress level and cavity width.</p>