加筋土边坡稳定分析安全判据和标准研究

Appraisal of Safety Criteria and Standards for Stability Analysis of Geotextile Reinforced Slopes

为了研究加筋结构稳定分析的安全判据和相关标准,基于库仑理论计算加筋土边坡安全系数的方法,将可靠度理论应用于目标可靠度指标为3.7、允许安全系数为1.34(较未加筋边坡的规范值略高)的一个典型算例中;并假定黏聚力c、摩擦因数f和筋材强度T的变异系数分别为0.2,0.1和0.07,获得其分项系数标定值为γc=1.38,γf=1.26和γT=1.05。基于相对安全率的概念,通过改变坡高、坡度和其他材料参数对上述标定值进行普适性论证;并采用承德机场工程实例对标定值进行了验证。结果表明:分项系数的标定值与国内外相关规定接近;普适性论证中良好的回归结果证明标定的允许安全系数和分项系数值与对应的可靠度指标具有同一风险控制标准;特别需要指出的是,随着坡度的增加相应安全指数的变化是平稳的,因此人为地将结构分类为墙或边坡是没有必要的。

To investigate the safety criteria and the related standards for stability analysis of geotextile reinforced structures,based on the Coulomb＇s theory to calculate the factor of safety for geotextile reinforced slopes,the theory of reliability analysis was applied on a typical example with a specified reliability index of 3.7and allowable factor of safety of 1.34（slightly higher than those required by codes for ordinary slopes）.Given the coefficients of variability for cohesion c,friction fand geotextile strength T,which are 0.2,0.1and 0.07 respectively,the calibrated partial factors that wereγc =1.38,γf=1.26 andγT =1.05 respectively were obtained.Furthermore,the applicability of the calibrated indices was investigated through the actualengineering project of Chengde airport slope.The results show that the calibrated partial factors are close to the related Chinese and overseas specifications,and the good regressions,obtained in all these circumstances,demonstrate that the calibrated allowable factor of safety and partial factors have the same risk control standards with corresponding reliability indexes.In particular,it is found that there exists a smooth transmission regarding all the calculated safety indices when the slope gradient becomes steeper.Therefore,it is unnecessary to divide the structures into wall or slope subjectively.