加筋土路堤稳定可靠性设计的分项系数优化

Partial factor optimization of stable reliability design for reinforced embankment

为了完善加筋土路堤极限状态设计方法,分析了加筋土路堤稳定可靠性设计的分项系数。基于大量工程实测资料和文献资料的统计分析,初步确定了填料密度、填料粘聚力、填料内摩擦角、汽车荷载、筋材抗拉强度、筋土似摩擦系数和路基几何参数等参数不定性系数的统计结果和概率分布模型。针对加筋土路堤的筋材拉断、筋材拔出、基底滑动以及整体滑动4种失效模式,按照抗力最小二乘原理,优化得到了相应的恒载分项系数、活载分项系数与抗力分项系数。计算结果表明:实例工程在4种失效模式下的总抗力均大于总恒载与总活载之和,同时安全系数均满足规范要求。可见,优化得到的分项系数合理。

In order to perfect the limit state design method of reinforced embankment, partial factors of stable reliability design was analyzed, the statistic results and probability distribution model of.uncertainty coefficients of random variables such as filler density, cohesion, angle of internal friction, vehicle load, tensile strength of geosynthetics, pseudo-friction coefficient and geometric parameters of embankment, were obtained preliminarily based on statistical analysis of field data and literature material. According to the least square principle of structure resistance, partial factors of resistance, partial factors of dead load, partial factors of live load of reinforced embankment were optimized in four failure modes including the fracture of geosynthetics, pullout of geosynthetics, basal slide and global slide. Calculation result indicates that resistance is larger than sum of dead load and live load under four failure modes, and safe factors can meet standard requirements, so the optimized partial factors are reasonable. 7 tabs, 5 figs, 16 refs.