Abstract
The Haoji railway in China is the longest heavy haul railway in the world, including 235 tunnels located along the 1837 km railway. With the increasing axle load of the new line and the basal deterioration of the existing heavy haul railway in China, studying the fatigue performance of the newly designed tunnel structure is essential. To study the coupling effect of the surrounding rock pressure and 30 t axle load train, in this study, we combined three-dimensional numerical simulation and three-point bending fatigue tests to investigate the fatigue performance of the basal structures. The results of numerical simulation indicate that the center of the inverted arch secondary lining is the position vulnerable to fatigue in the lower tunnel structures; the surrounding rock pressure performance exerts a stronger influence on the stress state of the vulnerable position than the dynamic train loads. The S–N formula obtained from the experiment showed that the fatigue life of tunnel bottom structures decreases with increasing surrounding rock pressure and dynamic load. In typical grade V surrounding rock and 30 t axle loads, fatigue failure will not occur in the newly designed tunnel bottom structures within 100 years if bedrock defects are lacking and pressure of surrounding rock is not excessive.
Highlights
Researchers reported that fatigue would not occur in the tunnel basal structures
To study the mechanism of basal degradation and the fatigue performance of the base structure of heavy haul railway tunnels, through numerical simulation, Xue [11] indicated that a loose basement leads to a significant increase in the maximum tensile stress of the inverted arch filling (IAF) and fatigue damage would occur under the long-term operation of a 30 t/axle load heavy haul train
The strain caused by the surrounding rock pressure was far greater the high static and low dynamic bilateral confinement stress state, a fatigue test system was than that caused bythe thebending train load
Summary
Researchers reported that fatigue would not occur in the tunnel basal structures. Rickstal et al [1]. To study the mechanism of basal degradation and the fatigue performance of the base structure of heavy haul railway tunnels, through numerical simulation, Xue [11] indicated that a loose basement leads to a significant increase in the maximum tensile stress of the inverted arch filling (IAF) and fatigue damage would occur under the long-term operation of a 30 t/axle load heavy haul train. Basal deterioration has appeared in many existing heavy haul railway tunnels, so analyzing the fatigue of the new line’s basal structures that are experiencing higher axle load and freight volume is essential. This paper studies the fatigue performance of a heavy haul railway tunnel under the action of high surrounding rock pressure and large axle load train and provides a reference for the durability design of heavy haul railway tunnel structures
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