高拱坝剪滑失效概率研究

利用故障树分析法对高拱坝进行风险分析..研究表明,上游溃坝和大面积山体滑坡等产生的高水位、强冲力的洪水是造成高拱坝剪滑垮坝的原因.根据剪滑溃坝机理建立了高拱坝剪滑失效模式的状态函数,该状态函数包含压应力、切应力、摩擦系数以及粘结力系数等4个非完全独立的随机变量,且具有非线性特征.应用统计推理和假设检验方法分析得知,压应力与切应力随机变量呈极值Ⅰ型分布,摩擦系数与粘结力系数随机变量呈对数正态分布.在将部分相关的极值型与对数正态分布随机变量转换为独立、正态随机变量的基础上,利用二阶矩法计算得到某高拱坝的剪滑失效概率为10-5量级.

Shear-slipping Failure Probability of High Arch Dam

Fault tree analysis is used to analyse the high arch dam risk. The analysis result shows that the shear-slipping collapse of high arch dam is caused by the flood of high water level and strong surging force resulted from upstream dam bursting and large-scale mountain land-slide. Based on the mechanism of shear-slipping dam collapse, the state function of high arch dam shear-slipping failure mode is established, and the function involves four non-fully-independent random variables, namely, compressive stress, shearing stress, coefficient of friction and coefficient of cohesion, and is of non- linear characteristics. By means of statistical inference as well as hypothesis test method, it is determined that the variables of compressive stress and shearing stress are of Extreme-value I Distribution and that the variables of frictional coefficient and cohesion coefficient are of Logarithmic Normal Distribution. Based on the approach of turning some of the relevant extreme-value-type and logarithmic normal distribution variables into independent and normal random variables, the shear-slipping failure probability of a high arch dam is worked out to be of the order of magnitude of 10^-5 by means of second-order moment method.