灌注桩竖向承载力的分项系数研究

在荷载规范给定的分项系数前提下,利用可靠度理论和一维随机场理论,对灌注桩单桩竖向抗压承载力由总安全系数设计方法过渡为分项系数设计方法进行了深入研究,并得出了对应上海地区3种确定灌注桩单桩竖向承载力的分项系数设计的理论公式。在由经验公式计算单桩竖向承载力的推导过程中,考虑了土的分层特点;而在按静力触探比贯入阻力计算单桩竖向承载力的推导过程中,不仅考虑了土的分层特点,同时还考虑了土性的相关性。同时推导出相应于3种分项系数设计方法的抗力分项系数公式,并说明了抗力分项系数的计算方法。所得结果可供规范转轨时参考。

ON PARTIAL FACTORS OF VERTICAL BEARING CAPACITY OF CAST-IN-PLACE PILES

The design method of the vertical compression bearing capacity of cast-in-place piles from one safety factor to partial factors is discussed. The reliability theory and one-dimensional random field theory are employed. For the three types of design methods to determine the vertical bearing capacity of cast-in-place piles in Shanghai area, theoretical formulae of partial factors are obtained. To derive the bearing capacity based on empirical correlation, the characteristics of earth strata are taken into account. To deduce the bearing capacity based on the specific penetration resistance of cone penetration test, both of the characteristics of earth strata and the correlation between soil properties are considered. Three formulae to calculate the partial factors of resistance are deduced, and the computational methods of partial factors of resistance are explained.