Reliability Analysis On Segment Cracking And Surrounding Soil Stability In Shield Tunnel Construction

By combining the reliability theory, FEM and combinatorial optimization, a practical reliability analysis method was proposed. By applying the method to the shield driven tunnel construction, the quantitative analysis was implemented and the method's practicability was illustrated. There are 3 aspects emphasized in this article:1 , The study on the key technique of reliability analysisThis research can be divided into two sections:The one is a new reliability analysis model. The model's workflow are showed as follows: â‘  calculating the stress and strain in the calculating zone by FEM, â‘¡searching the potential crack section by Dijkstra method, â‘¢normalizing the stochastic variables by numerical calculation method,â‘£calculating the reliability index of the investigated subject by reliability theory. The model could be served as a new method for reliability research on geotechnical engineering.The other is the study on the ground loss. Based on the definition of the ground loss, by reducing the elastic modulus of the tunnel's lining, a model imitating the ground loss was proposed. After the usage of this simulating model on specific condition, the quantitative relationship between the ground loss and the reducing index of the Young's modulus is determined.2, The reliability analysis on lining segment cracking resistantIn accordance with the reliability analysis model proposed above, the study on the segment cracking was carried out. Based on the reliability index and the sensitivity coefficient, various contour charts could be obtained. The research result gave a quantitative explanation to the cracking phenomenon. Meanwhile, a quantitative conclusion, that the jack push force, the eccentric distance and the concrete tensile strength are main factors of the lining cracking, was drawn.3, The reliability analysis of surrounding soil stabilityBy using of the ground loss data from Taipei tunnel projects and by using of hypothesis testing, the research result showed that it is acceptable to deem the ground loss (as a stochastic variable) is submitted to Gaussian distribution. Then, the reliability analysis model was applied to the overlap tunnel. The investigated subject is the stability of the soil body surrounding the overlap tunnel. The calculation results...