桩基竖向承载力的分项系数研究

Study on Partial Factors of Pile Vertical Bearing Capacity

桩基的竖向承载力由桩侧摩阻力和桩端阻力所组成。设置在分层土中的桩,其桩侧总摩阻力由桩所穿过的各土层的摩阻力所构成。在一般情况下,各土层的摩阻力不仅大小不同,而且变异性也各异。当采用极限状态设计原则,按分项系数设计表达式设计桩基础时,需要提供各土层设计参数的标准值及其分项系数。本文提出了一种基于试桩资料的统计方法,可以分別估计桩端阻力和分层土桩侧摩阻力的分项系数,其结果可作为编制规范的基础资料。

The pile's vertical bearing capacity, is composed of point resistance and skin resistance. The skin resistance consists of frictions provided from every soil layer which the pile goes through. In general, skin frictions vary not only in quantity but also in the coefficient of variation. When the limit-state design method is used for pile foundation design, it is necessary to determine the standard value for design parameters as well as the partial factial factors for each soil layer. In this paper, an approach has been presented for determining the partial factors on the point and the skin frictions of the pile. When the pile foundation design code is drafted, the results may be treated as the basic information.