Study On Maximum Gradient Of The Railway In The Difficult And Dangerous Mountain Based On The Integrated Optimization Method

Maximum gradient of the railway is a major railway technical standard which has global significance, having a big influence on the transport capacity of design line, engineering quantity and quality of operations, and even changing the direction of the line. Due to the limitation of complex topography and geological conditions for the railway in difficult and dangerous mountain, which has the characteristics of large proportion of the bridge and tunnel engineering, limited installation space station and so on. So how to make out the appropriate maximum gradient in the condition of the project can be implemented, making the risk between construction and operation lower, saving investment, improving transport ability, which will be a valuable and significant research.In view of the present decisions on maximum gradient still remain listing a number of indicators for qualitative analysis and judgment, while introducing the integrated optimization method to explore the economic maximum gradient which is suitable for difficult and dangerous mountain landscape features in our country.Firstly, this paper analyzes the technical characteristics of the railway in difficult and dangerous mountain and the factors which influence the decision of maximum gradient, determining the main factors to be auxiliary variables of the integrated optimization of maximum gradient.Secondly, using the theoretical analysis and multivariate statistical methods to work out the mathematical models including engineering costs, operating costs, purchase of rolling stock and other costs; considering the minimum of conversion engineering-operating costs as the objective function, using the transport capacity and requirements for the relevant variables as the constraint function, then setting up an integrated optimization mathematical model of maximum gradient.Finally, this paper gives a typical example of the railway in difficult and dangerous mountain to test the model, and in order to enhance the reliability of result, two methods are selected and realized by MATLAB, while giving a qualitative evaluation about the optimized result from the transport ability, topographic and geologic, economic rationality, traffic safety and others, which shows that the result is consistent with the objective law. Then compares the result with the Code for design of railway line and gives some advices about it.