Research On The Risk Analysis And Management Of Breakwater

In this paper, the risk analysis and management framework of breakwater engineering is studied. The evaluation system and related models are established to integrate the technical indexes with economic indicators or other nontechnical indexes. The work in this paper consists of four parts: study on the randomicity of ocean dynamic elements; research on the quantitative methods for the risks in breakwater engineering; discussion on the decision-making models for breakwater risk; exploring on the management of the remaining risk after the optimization of breakwater.In the first part, the risks of breakwater induced by the uncertainties existing in extremal distribution of ocean dynamic elements are discussed ahead. Then, the Artificial Neural Network technique is introduced to hindcasting the lost wave data in observation. Thereafter, the regional frequency analysis methods based on L-moments is put forward to solve the problem of being short of data samples in the parameter estimate of the extremal distribution by collecting the homogeneous data in neighborhood regions. Risk analysis on breakwater is not possible if the environmental conditions are not properly quantified. It appears that the traditional methods to describe the joint statistics of ocean dynamic conditions are not always consistent with the physical behaviour of wave conditions. An alternative mode is proposed to describe properly the joint probability distribution of ocean dynamic conditions by combining the statistical models with parametric physical models.In the second part, the first produce is the setting up of the fault tree of breakwater by analysing more than 200 cases of breakwater failures. Then, some reliability-based methods are provided for quantifying breakwater risk. A new idea is proposed to improve the precision of computing failure probability by combining Monte Carlo simulation with traditional reliability method. In the end of this part, two case studies, reliability-based stability analysis of rubble mound breakwater and deformation-based model quantifying meandering damage of caisson breakwater, are presented to verifying and discussing the application of risk evaluation theory in breakwater engineering.In the third part, several models for the decision-making of breakwater engineering are discussed. There is a focus on the introduction of the utility theory into this field so as to perform the multi-attribute decision making and measuring the risk attitude of decision maker.Through the risk analysis of breakwater engineering, various risks existing during the lifetime of breakwater could be exposed, which makes the management of remaining risk possible. In the fourth part, the method to determining the premium rate of the insurance of breakwater construction project based on the risk analysis is discussed.The capacity of breakwater against sliding is influenced heavily by the friction coefficient between the bottom of cassion and the rubble mound foundation. It is necessary to have an insight in the random behaviour of the friction coefficient. Based on a project, this paper presents an experimental study on the friction coefficient between rubber slap, a new engineering material against sliding, and the top surface of a rubble mound foundation in the end.