负摩阻力引起的桩身下拽力和桩顶下拽位移研究进展

Research progress of dragload and downdrag on piles by negative skin friction

简要介绍了土体沉降引起的桩侧负摩阻力导致桩身下拽力和桩顶下拽位移的原因、力学机制以及工程危害性;总结了近年来国内外负摩阻力问题的现场试验、模型试验、数值模拟和理论计算方法等方面的研究现状;指出了目前存在的主要问题——针对考虑桩顶下拽位移、地基土固结时间效应等因素影响以及减少负摩阻力措施方面的研究相对较少;介绍了一种既可以提高桩基竖向承载力又能有效降低负摩阻力对桩基影响的新桩型——扩底楔形桩.

The causes,mechanical mechanism and engineering hazards of dragload and downdrag on piles caused by negative skin friction owing to the settlement of soils were introduced. The worldwide research progress in the field tests,model tests,numerical simulation and theoretical calculation methods of the negative skin friction were summarized. The main problems in the present researches were put forward： that is,relatively scarce studies on the downdrag,consolidation time effect and measures for reducing the influences of negative skin friction. A new type of piles,belled wedge piles,which can improve the vertical bearing capacity of pile foundations and effectively reduce the influences of negative skin friction,were proposed.