极限荷载下桩身压缩综合系数ξ研究

Research on the Integrated Coefficient of Pile Compression under Critical Load

竖向荷载作用下桩顶沉降由桩身压缩量和桩端土沉降组成,且长桩桩身压缩量所占比重很大。而桩身压缩量包括桩身弹性压缩和塑性压缩,它受到许多因素的影响。对桩身压缩量进行理论分析,可以得到桩身压缩量的解析表达式。在实际工程中用综合系数ξ来表示,s_s=ξ(P_0L/E_pA_p)。本文通过对498根钻孔灌注桩静载试验实测数据统计分析表明:综合系数ξ随着桩的长径比的增大而减小,并存在着简单的线性关系,同时ξ随混凝土强度的提高而增大。本文揭示的桩身压缩综合系数ξ的规律对桩设计具有指导意义。

The settlement of the piles in pile group consists of the compression of the piles and the settlement of the soil at pile toe. The compression of pile shaft consists of elastic compression and settlement of the large diameter and super-long pile. The analytical expressions for the settlement could be obtained by the theoretical derivation, which is expressed with the integrated coefficient in engineering practice, that is Ss = ξ（P0L/EpAp ）. According to the statistic analysis on the measuring data from 498 board piles, the results indicate that the linear relationship between the length-diameter ratio and the integrated coefficient ξ which decreases with the increase of the lengthdiameter ratio and increases with the increase of the concrete strength. The rules obtained in this paper for the integrated coefficient ξ of pile compression would be useful to the design of pile.