Research On Optimal Selection Method Of Expressway Line Planning In Poor Geological Area

Line option of expressway is important for the beginning work of expressway planning. It will directly affect the desired effect of the project. Therefore, a number of evaluations including risk assessment, technique evaluation, environmental assessment and social evaluation have to be worked especially for bad geological area. Then some practical decision-making methods have to be made to select an optimal one from variant location projects finally.The paper takes the landslide at the entrance of BAINFAO Tunnel between ZK17+500 and ZK17+850 on Yongzhou-Lanshan Expressway in Hunan Province (BAINI'AO landslide) as the typical regions, and puts forward the principles of line option of expressway according to prevention of geological disarsters, benefit and environmental aspects. Based on the system analysis theories such as Analytic Hierarchy Process (AHP), Fuzzy comprehensive evaluation theory, this paper discusses the line option of expressway after closely analyzing the characteristics of expressway location design and establish a complete, feasible comprehensive evaluation indicater system of line option of expressway.The paper considers the decision making of variant expressway location projects as a process of multi-objective fuzzy optimization to make a comparison study between several directions of lines and effectiveness and appraisal of line option. A membership degree model is established which transforms the value of indices into the relative membership degree; The weight of each factor was determined by using the improved method of The Fuzzy AHP and by applying the advanced evaluation approach and the decision making model of multi-objective fuzzy optimal selection of variant expressway location projects to real case-Yongzhou-Lanshan Expressway, the decision making model proved to be practical.