SAFETY SYNTHESIS ASSESSMENT OF RIVER-WAY LEVEE

The safety of river-way levee relate with a lot of factor such as flood water level, rainfall, material property, levee section and river-way shape, etc. The seepage and slop failure of river-way levee often results from the combined disadvantage factors. Safety assessment of river-way is difficult due to fuzzy and uncertainty of levee safety factor. In this paper, based on the quantitative and qualitative analysis of levee safety factors, the system frame of analytic hierarchy process (AHP) for river-way levee safety is presented. The valuation aggregation of levee safety including external and internal factor was discussed. Water level, rainfall, flood, river scouring and engineering grade are the external factors. Internal factor means the character and parameter of levee body and foundation such as clay content, dry density, size-grade distribution of levee material, percent saturation, levee level and percolation gradient, etc. Besides internal and external factors mentioned above, levee defect and its remedy measure also are important for evaluating the levee safety. Topping, outburst, avulsion and their compounding are the failure pattern of levee and dependent on the effect factors of levee safety. Whereafter, the effect of all factors on levee safety and the possible failure was discussed, the static weight model of extension AHP and expert interval marking method are used to the safety assessment of the levee engineering. In the end, the representative section of Yellow river levee was taken as an example and a computer system for safety synthesis assessment of river-way levee was developed by using fuzzy comprehensive appraisal method to syncretize the effect of all factors of levee safety.