Study On Natural Environment Evaluation Indicator And Zoning For Highway In Gansu Province

Gansu province locates in inland China. The unique geomorphology of Gansu province consists of the loess plateau, Inner Mongolia plateau, Tibetan plateau, western Qinling, Qilian mountain and Arjin mountain. Eastern monsoon areas, northwest arid areas and Tibetan high-cold region present various climate types in Gansu province. Internal and external flow composed of Yellow river, Yangtze river and inland river presents various hydrologic environment. There are also many kinds of geotechnical materials with complex genesis and different engineering characteristics and rich vegetations in Gansu province. All these form the natural environment of Gansu province and also bring up significant time-space and regional difference. As artificial works constructed in natural environment, highway passes various regional units. The highway is affected by natural environment during both construction and service stage. At the same time the construction of highway will affect natural environment, especially the vulnerable ecological environment of Gansu province which requires sufficient attention.Referring to the theories and methods of natural zoning the author reveals the regional differentiation rules of natural conditions in Gansu province on the base of exploration of environment parameters and zoning using GIS and the partial reseach results of natural zoning for Gansu highway. The internal mechanism of interconnection and mutual restriction among natural factors and between highway construction and natural environment is analyzed. Amount and properties of natural resources of different regions are revealed, which is helpful to highway construction.Difficulty degree index of highway determined using six factors represents the influence of natural conditions in different region on highway survey and design, construction and maintenance. According to analyzing and calculating climatic factors which have great influence on highway construction, disadvantage climatic factor is determined for macro-decision of highway construction. According to requirement of highway construction and engineering characteristics of geotechnical materials, utilization index of geotechnical materials is determined for the design, construction and maintenance of highway. According to analyzing and calculating four types of natural factors which have great influence on scouring of subgrade slope, slope runoff index is determined for basis of macro-decision, investment control and design inspection of department in charge of highway construction. And the slope runoff index is also the basis data for highway net planning, design, construction and maintenance. According to analyzing and calculating seven types of geological disaster which have great influence on highway construction, disaster degree index is determined for highway net planning, design, construction, maintenance, disaster prevention and reduction in Gansu province.The study on natural environment indices parameters and zoning of highway is the deepening and development of natural zoning for highway. And it also has important economic, social and environmental benefits and positive theoretical significance on highway construction.