尾矿坝属性参数概率分布类型及变化趋势研究

摘要

The existing studies think that most of the tailings dam attribute parameter obey central lim-it distribution.But the actual property parameter scope is limited,which cause problems that central limit distribution is not enough to characterize the non-normal distribution characteristics of the parame-ters and low fit is produced between fitting distribution model and the distribution interval of the actual parameters.Considering that the dam attribute parameters have nonnegative values and there is skew-ness,the value scope of sample distribution is determined by using the""standards with the skewness of sample data.;Different probability density curve and cumulative probability function curve are fitted by the typical distribution fitting method on the basis of parameter skewness characteristics.The proba-bility distribution model of the parameters are inferred and tested by the chi-squared and K-S test.After determining parameter distribution types,attribute parameter variation trend analysis is made by Man-Kendall method.The result shows that the cohesive force distribution of consolidation drained shear tests showed left skewness values of characteristics,while others showed right skewness.The cohesive force obeys the extreme 1-type distribution and the internal friction angle obeys logarithmic normal dis-tribution in consolidated drained shear and undrained shear experiment.Cohesive force and internal fric-tion angle are distributed to normal distribution in consolidated undrained shear experiment.The cohe-sive force in both consolidated drained shear and undrained shear experiment showed a downward trend after the period of fluctuation.However,the overall internal friction angle of the three groups showed a significant upward trend after the period of fluctuation.%现有研究认为大多数坝体属性参数服从中心极限分布,但由于属性参数实际取值范围有限,导致采用中心极限分布不足以表征参数的非正态分布特性,造成所拟合分布模型与实际参数分布区间契合度低等问题.考虑到坝体属性参数具有非负值,且存在偏度,首先用"3σ"准则结合样本数据的偏度确定样本分布取值范围;根据参数偏度特征利用改进的经典分布拟合法拟合出不同分布概率密度曲线和累积概率函数曲线,从而对参数概率分布模型进行推断,并根据卡方检验法、K-S检验法进行检验;在确定参数分布类型后,利用曼-肯德尔法对参数变化趋势作出分析.研究结果表明:固结排水剪切试验中粘聚力分布取值表现出左偏态特征,其他实验下参数取值均表现出右偏态;固结排水剪切和不排水剪切实验中粘聚力服从极值I型分布,内摩擦角服从对数正态分布;固结不排水剪切实验中粘聚力和内摩擦角均服从正态分布;固结排水剪切和不排水剪切实验中粘聚力在经历波动期后均表现出下降趋势,而3组实验中内摩擦角整体在经历波动期后均呈现显著上升趋势.