Study On Safety Assessment Of Seawall

Seawalls are extremely significant facilities against storm surges attack and important parts of the flood protection and tidal control system in Zhejiang province and other coastal areas. Because the damage and lose brought by typhoons, rainstorms and other natural disasters can reduce effectively by these seawalls which are important guarantees of the lives and property safety of surrounding people. Safety assessment of seawall is an important preliminary work of seawalls reinforcement. And the research of making the scientific and rational assessment for the seawalls to clear the current security level and provide the design basis for reinforcement has important theoretical and application value, while it is of great importance to timely response to the severe flood situation, reduce disaster losses and ensure public safety. On the basis of consulting a large number of literature and taking example by the methods and experience of the dams and other hydraulic structures safety assessment, the multi-level comprehensive assessment technology for seawalls has deeply discussed and researched, and comprehensive assessment model of seawalls has been built. The main research contents and conclusions are as follows.(1) Build the safety assessment system of seawall. According to the characteristics of seawall project, a multi-level index system of comprehensive assessment of seawall has been bulit. At the same time, the selecting principles of assessment unit and typical sections have been defined, which lays the foundation for the subsequent assessment of seawall.(2) Determine the assessment index weight of seawall by combining the analytic hierarchy process (AHP) and Delphi method. And the weight of AHP and Delphi are determined by the relative error of computing the index weight, then final weigh of the index can be got by the weighted average method.(3) Formulate assessment criterion of index. The assessment index is divided into the qualitative and quantitative indicators. The assessment criteria and scoring range have been drawn up in the light of the seawall safety classification standards.(4) Build a fuzzy comprehensive assessment model of seawall. The membership degree of qualitative indexes is determined by expert assessment method and fuzzy statistical principle while the membership degree of qualitative indexes is determined by the grading and membership functions. The membership assessment vector of the target layer can be got by comibining the index weight to make comprehensive judgement step by step, then the security level of seawall can be fixed according to the basis of the maximum membership principle. Simultaneously, the overall rating and corresponding safety level can be obtained by the score of single index and weight as AHP. Therefore the security level of seawall can be determined in the light of the comparative analysis of the two assessment results.(5) The application of safety assessment model of seawall. Taking the Kaomen seawall in Daishan County of Zhejiang Province for an example, the result got by using comprehensive assessment mathematical model shows that Kaomen seawall belongs to unsafe level. After analyzing the existing maining problems of seawall, the advices of reinforcement to the seawall are suggested.