海洋平台打入式桩基抗拔承载力的时效性分析

摘要

采用ABAQUS软件对海洋平台打入式桩基的抗拔承载力的时效性进行了数值模拟分析.研究了海底土体的渗透系数对桩基的超孔隙水压力消散及桩基径向有效应力的增长规律,进行了桩基上拔的模拟分析,得到桩基抗拔承载力随时间增长规律,建立了上拔荷载—位移的关系,并考虑了上拔过程中桩底负压对抗拔承载力的影响.提出关于无量纲时间因数T和土压力系数K的抗拔承载力时效公式,并现场测试数据进行了验证.研究结果表明,渗透系数越大,超孔隙水压力消散越快,桩基的径向有效应力增加得越大,桩基的抗拔承载力增加得也越大.桩底负压虽然对桩基的抗拔承载力是有利的,但是其在桩基承载力中所占比例很小.%ABAQUS software is used to analysis the set-up effect on uplift bearing capacity of driven pile foundation.The soil permeability on soil excess pore pressure dissipation,the relation between radial effective stress and time are investigated.The relation between bearing capacity of pile and time are also studied.At the same time the suction pressure is taken into account.A new formula which is about nondimensional time factor T and stress coefficient K is provided to calculate the uplift bearing capacity.The results indicate that with the permeability increasing,the excess pore pressure dissipates more quickly,the radial effective stress and uplift bearing of pile increase more rapidly.Although the suction pressure at the end of pile is beneficial to the uplift of pile,but it takes small percent of the bearing of pile.