Based On The Risk Assessment Of The Soft Soil Area Foundation Excavation Fuzzy Evaluation Method

China is a country with large population and scarce land resource. Particularly, the land for urban construction is getting increasingly tense. With the rapid development of the high-rise building technology, skyscraper has become an indispensable element in urban space and also relieves the tense situation of construction land. However, the frequent excavation engineering accidents have cause casualties, great financial losses and very bad impacts on the society in recent years. So it becomes particularly important to ensure the safety of construction activities in the southeast coastal of China whose foundation pit conditions are worse. Risk management methods are researched and applied in engineering practice in this paper according to the construction characteristics of soft soil excavation engineering.Firstly, according to the construction characteristics in the soft soil area, the failure tree of the six excavation engineering risk events is established based on the theory of failure tree analysis (FTA). The risk factors in construction process are identified and a risk assessment calculation model is established in this paper.Secondly, combined with the uncertainty characteristics of excavation engineering in the soft soil area, fuzzy evaluation method is proposed based on the analysis of risk assessment methods home and abroad. The pairwise comparison judgment matrix is established by Nine-Standard method when solving the weight vectors of the factors. The concept of fuzzy reciprocal judgment matrix is proposed for the consistency problem of the judgment matrix. The problem is solved properly by optimizing the Nine-Standard for fuzzy-scale. Finally, the result of theoretical research is applied to the excavation engineering in technical detection center of Fujian Province. And the model achieves a good performance and satisfactory results by risk assessment, process tracking and other means for risk controlling. The experiments verify the feasibility and effectiveness of this method and indicate that it can be widely used for the risk management in other similar excavation engineering.