显式和隐式方法求解防波堤可靠度的差异分析

摘要

半圆形防波堤具有稳定性高、结构简单、便于施工等优点.以往对其进行可靠度计算时,根据波高与周期,计算防波堤受到的荷载作用,将荷载作为随机变量,估计其概率分布模型,建立显式的极限状态方程,再进行求解.计算得到的波浪荷载序列对于最优分布线型的离散程度较差.采用基于隐式功能函数的防波堤可靠度分析方法,将波高和周期作为随机变量,无需计算波浪荷载这一中间序列,规避了误差的产生,简化了计算流程.分别采用隐式与显式两种方法对半圆形防波堤进行了可靠性分析.结果表明,两种方法得出的可靠度指标存在差异,这种差异是由于波浪荷载拟合时所产生的误差造成的.%The semi-circular breakwater has many advantages,such as high stability,simple structure,and convenient construction.In previous research on the reliability of this type of structure,wave loads of breakwater were calculated through the wave height and period,which were regarded as stochastic variable.Estimating the probability distribution models of the above parameters,then the explicit limit state equations can be established and solved.It should be noticed that,for the sequence of wave loads calculated,the dispersion degree of the optimal distribution is poor.Thus,this paper proposed a method of reliability analysis of breakwater based on implicit performance function.Wave height and period are regarded as stochastic variables without the needs of constructing wave loads which are considered as intermediate variable sequence.It is able to avoid the error and simplify the calculation process by this approach.Both the explicit and the implicit methods are applied to calculating the reliability of the semi-circular breakwater.The results show that the difference of the reliability indexes by these two methods is caused by the fitting error for wave load distributions.