Dynamic Response And Fatigue Lifetime Analysis Of The Segment And Joint Under Train Cyclic Load

With the rapid development of subway construction in China, the operating mileage keeps increasing every year with its service time increasing gradually. Because of long-term high-density operation, and some initial imperfections in the construction, a series of subway tunnel diseases will appear inevitably, affecting the normal use function, and even the running safety when seriously. In order to meet the requirements for the useful life of100years, prediction of fatigue life of the subway tunnel will be particularly important. According to the long-term service lifetime of subway shield tunnel, this dissertation is granted from the National Basic Research Program of China (973:2011CB013802), the dynamic response rule of the shield tunnel under different formation conditions is analyzed, and also the fatigue lifetime of the fatigue dangerous position is predicted by using numerical calculation method. The main research contents and conclusions are as follows:(1) The mechanism of structural fatigue damage is analyzed, some common methods of fatigue lifetime analysis are introduced, the existing fatigue cumulative damage theory and stress-life curve (S-N curve) are summarized, and the prediction equation of the fatigue time suitable for this paper is determined.(2) For the structure of the shield tunnel segment, combining with tunnel-surrounding rock system vibration theory, shield tunnel segment detailed models with different depth under the staggered assembling are built. The law of the train vibration propagation in lining direction is analyzed from vertical displacement, vertical acceleration and dynamic stress. The position greatly influenced by vibration is defined. And the change rule of dynamic response at different part of the lining structure under different depth.(3) When the basement void appears, the influence law and its degree of dynamic stress response of different part in the lining structure affected by void range are analyzed, and comparison analysis with the influence of depth is made.(4) For different depth and condition of basement void, the fatigue lifetime in the dangerous part of shield tunnel is calculated and analyzed by Fe-Safe. According to the requirement of the lifetime, and whether the structure meets it is estimated.