扩底楔形桩竖向抗压和负摩阻力特性研究

Study of characteristics of compression capacity and negative skin friction for belled wedge pile

扩底楔形桩是基于结合常规扩底桩和楔形桩的优点而开发的一种新桩型,能同时提高桩侧正摩阻力和桩端阻力,并能有效降低土体沉降引起的负摩阻力对基桩的影响。简要介绍了扩底楔形桩的受力机制和施工方法;基于FLAC3D有限差分软件,通过针对实际工程的数值模拟验证数值模拟的可靠性,对该新桩型在竖向抗压和负摩阻力特性方面的力学特性进行了初步探讨,并与等体积混凝土的常规扩底桩、楔形桩和等截面桩进行了对比分析;进而研究了桩端土体与桩周土体模量比、楔形角、扩大头直径以及桩体模量等因素对扩底楔形桩力学特性的影响。研究结果表明,同等级地面堆载作用下,扩底楔形桩中桩侧负摩阻力引起的桩顶下拽位移最小、桩身下拽力值介于常规楔形桩和扩底桩两者之间。

Based on conventional belled pile and wedge pile,a new type pile,belled wedge pile,which can improve pile shaft friction,tip resistance and reduce the influence of negative skin friction is developed.The stress mechanism and construction method of belled wedge pile is briefly introduced.Based on FLAC3D,The results are verified by engineering examples analysis;the mechanical properties on compression capacity and negative skin friction of belled wedge pile is preliminary studied.Conventional belled pile,wedge pile and equal section pile which are in the same concrete volume are comparatively analyzed.The mechanical properties of belled wedge pile which influenced by modulus ratio of pile end soil and pile surrounding soil,wedge angles,the diameter of enlarged pile head and the modulus of pile are discussed.It is shown that,when in the same surface load grade,the downdrag of belled wedge pile is minimum;the dragload of belled wedge pile is between the values of conventional belled pile and wedge pile.