Abstract: By introduction of reliability to the asphalt mixture design，the adverse effects of asphalt-aggregate ratio ( Pb) variation on performance of mixture is reduced． Exceeding the limits of the volume indicator is defined as failure，and thus the concept of confidence interval is raised． Reliability is got by Pb integration of probability distribution function in confidence interval． Make the reliability as evaluation index to optimize grading of SMA-13，in order to keep the pavement performance when reliability of SMA-13 is increased by 42． 9%． Nomogram of confidence interval，Pb standard deviation and reliability is drawn，and after combination of research，we can get that: recommendable confidence interval of mixture used in highway and other roads should not be less than 0． 6% and 0． 5% respectively，and reliability of highway and other roads should not be less than 95% and 80% respectively．

Key words: highway engineering, reliability, mixture ratio, volume parameter, grading, construction controlling, probability distribution

摘要： 引入可靠度理论至沥青混合料配合比设计，减少施工油石比( Pb ) 变异对混合料性能的不利影响。将混合料 失效定义为体积指标超出限值，由此提出可靠区间概念。用Pb 概率分布函数在可靠区间内积分得到可靠度。以可 靠度为评价指标对SMA-13 进行级配优化，使SMA-13 可靠度提高42． 9% 的同时不降低其路用性能。绘制可靠区 间、Pb 标准差与可靠度的诺模图，结合调研推荐: 高速公路混合料可靠区间应≥0． 6%，其它道路≥0． 5%; 高速公路 混合料可靠度应≥95%，其它道路≥80%。

关键词: 连续刚构桥, 收缩徐变, 桥面铺装, 有限元分析