| According to China’s railway "long-term railway network planning (2008adjustment)", during the twelfth Five-year plans, there will be existing railway line rebuilt and second railway constructed project of19thousand kilometers, which required in both investigation and design. Meanwhile,it is also required in many other aspects such as the line design and construction etc by maximize the use of new technology, new methods and new equipment efficiently and accurately. Due to the large number of existing equipment, during the rebuilt of the existing railway design process, the limiting factors in the transformation process are so complex that it must be especially considered in methods, ideas and other aspects in design as it is quite different to the new line. Especially in the longitudinal design of the existing lines, more limiting factors should be considered in the optimization algorithm, due to the influence of a large number of bridges, tunnels and existing equipment of stations. Experts and scholars both home and abroad did a large number of studies and has obtained a series of research results,using the linear programming method, the gradient projection method,the dynamic programming method etc. However, due to the difference in regions, the specific circumstances of each line are different. Western Railways are of the characteristics such as small radius curves, maximum limiting gradient slope sections, numerous bridges and culverts (esp. open deck) and shorter station spacing. There are a variety of shortcomings in the optimization design methods. Therefore, a optimization method to adapt to the complex areas of the west existing rail longitudinal is particularly necessary.In this paper, according to the transformation of the actual needs of western railway line, the optimal design method, programming, automatic drawing are completed as following:(1) Study at home and abroad Profile Optimization Design of algorithms and computer-aided design development status,combined with the existing railway longitudinal alteration of design features, using combined with the golden section method and the least squares method, made existing railway optimal design method,and the point of gradient change judgment, the optimization of single-slope segment, the slope adjustment made a detailed analysis.(2) Take full account of the Northwest rail longitudinal alterations to the many features of the design constraints, It designs existing railway longitudinal alteration model which based on Genetic Algorithms by slope and Slope length. This method gives full consideration to the conditions such as slope, slope length, Slope algebraic difference, Vertical control points, Line space curve(includes:vertical curve does not overlap with the transition curve, vertical curves does not overlap with the turnout, vertical curves should not be based on the open deck and there are too many existing buildings along the route)and so on, so that it can effectively solve the question that there are too much constraints at existing railway longitudinal alteration design.(3) Due to existing optimization procedures are mostly output design results in EXCEL for searching, but the results of longitudinal alterations design need the form of amplification longitudinal to show up, design the existing line longitudinal auxiliary CAD system, develop auxiliary CAD system which based on EXCEL data source by VBA programming language, directly using external investigation data optimize generate line amplification longitudinal, it is also can generated by artificial design data. The program has the characteristics of simple operation, results reliable, has some reference value in the following study. |
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