Study On The Natural Environmental Impact Assessment And Protection About Changde-Jishou Freeway Construction

With the implementation of the big development of West China,a lot of large engineering projects will have a great impact on natural environment. Because of the highway construction project's long construction period and large area of operations, once the highway construction project lacks of environmental impact assessment and correctly protective measures, it will result in more serious environmental and ecological destruction.Basing on the west region communication construction technology project of the Ministry of Communications"Comprehensive Technology Study on the Protection of Cultural Heritage and Natural Environment along the Changde to Jishou Freeway", This article has studied on research the Natural Environmental Impact Assessment and Protection Measures.According to the entitative engineering of Chang-Ji Freeway Construc- tion Project and the survey of it's natural environment, consider the natural environment biggest protection and smallest destruction, this article selects 23 indexes to make analysis and set up hierarchical structure of Index System, which are mainly from 5 aspects including the highway alignment, the bridge, the tunnel, the protection engineering and the appurtenant works, and the23 indexes are average vertical slop, average fill height, average cutting depth, earth quantity/km, occupied area/km, alignment coordinated with environment, bridge length/km, construction difficulty, bridge type coordinated with environment, The impact of a bridge on the river, the closest distance of bridge from the source of local drinking water, tunnel length/km, portal part form, excavation height of side and face upward slope, interference of tunnel to groundwater balance, the average quantity of protection engineering/km, proportion of planting protection, vegetation coordinated with the local place, engineering quantity of the river changes, proportion of borrow soil amount to filling, proportion of soil pits greening, proportion of discarding soil amount to excavation and proportion of spoil bank greening and so on.Based on the great deal of investigation and analysis, combined with related standard, this article has determined grade standard of each index.Made an analysis and comparison of the different evaluation methods and evaluation models, combined with Chang-Ji freeway Construction Project and evaluation index system,the article has selected analytic hierarchy process(AHP) and entropy method for the evaluation of natural environment protection design. Based on the combination of two methods,it has proposed a comprehensive weight determination method and related evaluation model,which could overcome the obvious subjectivity of AHP weight, consider some qualitative indexes and the requirements of entropy method to quantitative of indexes simultaneously.The effects of the entity for the project show that the index system, the Weight Determination and Evaluation Model of this paper is objective, reasonable, has a theoretical significance and value engineering practice.Based on the environmental impact assessment and decision-making, this paper proposed the protection of the natural environment of the specific methods and measures from the design of the road, bridge and culvert design, tunnel design, protection design and so on.These measures have been used in Changde-Jishou freeway project and have got a positive effect.