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The tunnel is an important part of mountain highway engineering, while the tunnel structure type preferred is an important part of the design of the tunnel line selection. The mountainous highway tunnel structure type separate, double-arched, small spacing and bifurcated structure, used mainly when the preferred method of qualitative analysis, its inadequacies is to treat selected by virtue of the subjective judgment of the people The characteristics of the tunnel structure type were analyzed merit prone to only the most concerned about the impact of factors, while ignoring other factors, it is inevitable ill-considered, and more difficult to get the recognition of other people, recognized as poor. The theoretical analysis, the nature of the problem of mountain highway tunnel structure type preferred on multi-objective decision-making is limited by the combined effects of a variety of factors program. Determine the target weight, decision makers are often unable to determine the the target importance of accurate values ??usually only fuzzy linguistic variables, such as very important, important, unimportant, etc. to express the same ambiguity in this type of multi-objective decision making problems there are often qualitative indicators of program corresponding target value, that is the kind of problem overall showing fuzzy characteristics using fuzzy optimization method is essential requirement of the aggregate the tunnel structure type preferred. The study employed a combination of theoretical analysis and field application research tools, systems and in-depth research to build mountain highway tunnel structure type fuzzy optimization theory and methods, the instance of the application of Shiman Expressway Tunnel, mainly to obtain the following results: 1 mountain highway tunnel characteristics of different structure types: (1) separate tunneling technology is the most mature, suitable for all kinds of tunnels especially older, long tunnel, its shortcomings, mainly as a result of the double-hole spacing caused road tunnel external wiring inconvenience, covers an area not suitable for the construction of the narrow strip of mountainous terrain. (2) The technical characteristics of the double-arch tunnel with separate tunnel contrary, its wiring convenient, less floor space, and most should be built in the narrow strip of mountainous terrain; difficult technical methods, construction procedures, long construction period, the project cost high, it is not appropriate to grow up, long tunnel. (3) the technical characteristics of the small spacing tunnel between separate tunnel with double-arch tunnel between the pros and cons of the extent of its programs is closely linked with the size of the tunnel clear distance, at the same time, the small spacing tunnel, there are some technical problems yet to be studied currently, it is inappropriate to grow up, long tunnel. (4) bifurcated tunnel both separate, double-arched, small spacing and the technical characteristics of a large span tunnel overcome various tunnel structure type grew up in the mountains, the difficulties in the construction of the long tunnel, but also produce a some technical problems, mainly in the mountainous bridge and tunnel connected terrain very difficult, in the specific application of the comparison should be based on the actual engineering separate tunnel. 2, build a mountain highway tunnel structure type preferred comprehensive evaluation index system includes a total of terrain conditions, geological conditions, technical conditions, economic conditions, as well as resources and environmental conditions of the five-level indicators. Which indicators of terrain conditions, including the tunnel length, tunnel alignment layout and wiring convenience, hole conditions, the burial depth of four secondary indicators; geological conditions indicators including lithology, degree of fragmentation of rock mass, groundwater, special geological conditions of four two indicators; technical condition indicators include two secondary indicators of the degree of difficulty and duration of construction technology; indicators of economic conditions, the the tunnel unit segment cost metrics; resources and environmental condition indicators to the occupancy of land and water resources and the extent of the damage to metric. These indicators, the tunnel unit segment (refers to both sides of the tunnel, due to the different types of tunnel structure due to the distance between the start and end points of the line changes) cost for the smaller and more excellent \indicators need to rely on the experience of the people were analyzed. Fuzzy optimization theory, based on multi-level and multi-target system, the establishment of a mountain highway tunnel structure type fuzzy optimization system, comprehensive evaluation index system by the optimal solution, the tunnel structure type, the candidate tunnel structure type program set. Solving the system starting from the lowest level of the basic unit of the system, according to the weighted average model fuzzy operation, as the upper layer of the corresponding input, the lowest level of output then continue to solve, the obtained result is more on the layer of the input and so on and so forth, from low-level to high-level step-up, until the highest level. The most high-level output of the decision-making set relative membership degree vector relative membership degree of decision-making relative membership degree of sorting for optimal decision-making, decision-making set-satisfied sort of decision-making set. 4, using the binary comparison method to determine the index weights and relative membership degree of qualitative indicators, depending on the type of quantitative indicators (the bigger the more gifted, the smaller and more excellent) based on eigenvalue choose the appropriate formula to determine the relative membership degree between these two method for determining the unitary character of the qualitative indicators and quantitative indicators mixed mountain highway tunnel structure type suitable for solving fuzzy optimization problems. Mountain highway tunnel structure type fuzzy optimization system of universal significance, practical application should be corrected according to the specific circumstances of the project system, followed by the establishment of appropriate engineering tunnel structure type fuzzy optimization system. 6, the of Shiman highway tunnel structure type fuzzy optimization results well represented at this stage about the conditions of application of the different tunnel structure type. Preferred results can recognize that, for the short tunnel, in the not very demanding lots of terrain conditions, if the surrounding rock is of poor quality, double-arch tunnel optimal surrounding rock quality is better, the small net from the tunnel optimal; lot of very harsh terrain conditions, regardless of the surrounding rock quality, always double-arch tunnel is appropriate. 7, in order to ensure the fluency of the line alignment, of tunnel group structure type should be considered as a whole, unified, the first individual in a separate preferred, then the preferred results were weighted superposition (weights are given based on the length of the tunnel) get overall a preferred embodiment of the method is simple and feasible. 8 the developed mountain highway tunnel structure type fuzzy to the preferred auxiliary complete computing system embodies the philosophy of the tunnel structure type fuzzy optimization, improve computational efficiency, but also conducive to the promotion and application in the project site. In short, paper is more systematic study the mountainous highway tunnel structure type fuzzy optimization theory and methods, and and developed corresponding auxiliary computing systems, achieved good results. This fuzzy optimization theory or other quantitative multi-objective decision theory approach to the tunnel structure type is preferred to provide a reference.
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