Comprehensive evaluation on stability of roadbed of high-speed railway in seasonal frozen regions based on fuzzy mathematic

Harbin to Dalian Passenger Dedicated Line(HDPDL) is the first high-speed railway for construction and operation in cold regions in China, which have prominent social and economic significance. To realize the multi-factors quantitative evaluation on the roadbed stability in high-speed railway in seasonal frozen regions,a fuzzy comprehensive evaluation method is proposed on the basis of the theory of fuzzy mathematics. Based on the principle of operability and representativeness, five primary factors and sixteen secondary factors are established, containing the roadbed fillings、the engineering conditions、the hydraulic environment, the heat environment and the geological and geomorphologic unit. The analytic hierarchy process(AHP) is used to distribute rational weight for every factor, a comprehensive evaluation system is constructed where factors are quantitatively graded according to five stability grades by using fuzzy statistical method and experts grading method,to analyze the conformation of membership function of every factor. And the fuzzy synthetic evaluation method is advanced based on the safety reliability. By applying the method the stability reliability of Changchun West test roadbed was 0.889 7, and according to the weighted average method evaluation the whole system, the final score was 72.902 points, which showed the roadbed was in a stable state. Comparing the test project in Changchun site,a satisfying evaluation result consistent with engineering reality is achieved. Fuzzy comprehensive evaluation method proves to be rational and operable for evaluating the roadbed stability in high-speed railway in cold regions,which therefore provides theoretical support for design methods and operation.