Accurate estimation of soil shear strength parameters

抗剪强度参数统计特征的精确估计方法（英文）

The cost and safety of geotechnical engineering are highly depending on the accuracy of soil shear strength parameters.There are three methods often used to estimate soil shear strength parameters,i.e.,moment method,3-sigma rule and linear regression method.In this study,the accuracy of these three methods is compared.Traditional linear regression method(LRM)can only offer the mean of shear strength parameters.Some engineers misuse the standard error of shear strength indexes as the standard deviations.Such misuse may highly underestimate the uncertainty and induce high risk to the geotechnical design.A modified LRM is proposed to determine both the mean and variance of shear strength parameters.The moment method,three-sigma rule and LRM are used to analyze the tri-axial test data in Xiaolangdi Hydraulic Project and three numerical shear strength tests.The results demonstrate that:1)The modified LRM can offer the most accurate estimation to shear strength parameters;2)A dimensionless formula is much preferred in LRM rather than a dimensional formula.The stress ratio formula is much better than stress relation in the shear strength parameter analysis.The proposed method is applicable to shear strength parameter analysis for tri-axial test data,direct shear test and the un-drained shear strength test of stratified clay.

强度参数的精度对岩土工程的成本和安全都至关重要。首先,本文对比了三种现有的强度参数统计特征计算方法的精度。在工程实践中,线性回归中的均值方差经常被误用为强度参数的方差,这会导致很大的误差。本文提出了一种改进的线性回归方法,它能够精确估计强度参数的均值和方差。改进的线性回归方法被用于小浪底心墙坝的抗剪强度数据分析,结果表明:改进线性回归方法能够提供最精确的强度参数估计;将无量纲的公式用于线性回归效果要好于有量纲的公式。本文提出的方法不仅能够用于三轴强度数据的分析,还可以应用于直剪数据分析以及成层土体的不排水强度分析。