Research On The Select Schemes Of Embankment And Bridge For High Speed Railway Based On Grey And Fuzzy Sets Theory

In newly constructed railways, especially segments of soft base in high-speed railway and regions of plateau permafrost, the program "bridge on behalf of subgrade" was generally adopted in railway design in order to control subsidence, to improve the smoothness and stability of route structure. The core issue of "bridge on behalf of subgrade" is how to choose boundary height of subgrade and bridge. With the large-scale construction of high-speed railway, the selection of schemes in subgrade and bridge boundaries had become one of the issues focused on by the railway design department. Because of the complexity and comprehensiveness in subgrade and bridge boundaries scheme decision-making, the current researches towards this theory were mostly theory-based and not mature enough with many deficiencies. Therefore, based on systems engineering theory, grey theory, fuzzy multi-objective decision-making theory; this paper presented a relatively systematic and comprehensive research through the method of systematic engineering and compound decision by combining stationary and quantitative index.Firstly, it took a comprehensive research towards the factors which affected the choice of subgrade and bridge boundary scheme. A system of evaluation was established according to integrity, scientific, independence and maneuverability.Secondly, evaluation index weight was calculated by the way of the grey relational analysis method. Therefore, the relation between economic and non-economic factors in program evaluation was represented while the subjectivity in empowerment was avoided, resulting in a more reasonable index weight.Thirdly, it established the subgrade and bridge boundary scheme comparison and selection model based on grey theory and fuzzy set theory through the research on the basic theoretical method and evaluation process of the two theories. It gave detailed explanations of the evaluation decision process of subgrade and bridge boundary scheme comprehensive evaluation and listed out related calculation steps.Finally, it founded a subgrade and bridge boundary scheme comprehensive evaluation model of some section, taking newly-built Shanghai-Nanjing Intercity Passenger Dedicated Railway as example, carried on comprehensive evaluation of influencing factors and evaluated the boundary scheme combined with the evaluation results above. The calculation results of the case verified the correctness of the scheme comprehensive evaluation model, showing that using this countermeasure to optimize the subgrade and bridge boundary scheme having some reference value to production practice.