考虑固结群桩竖向应力相互作用的积分方程分析方法

发布时间：2019-03-11 15:21

【摘要】：采用Biot固结方程,分别以等长和不等长两桩为分析对象,将受竖向荷载作用的桩土体系分解成半空间饱和扩展土和虚拟桩,基于竖向应变协调关系建立桩土相互作用的第二类Fredholm积分方程,求解出不同固结状态时的桩身轴力分布。在等长两桩中,由于邻近桩的存在,桩身附加轴力主要分布于桩身20%~80%深度处,其影响程度随着桩间距的增加而减弱。进一步将等长两桩分析扩展至群桩研究中,分析表明:群桩效应引起了桩顶荷载的不均匀分布;土体固结对桩身内力分布也有一定的影响,固结后角桩承担的荷载有所下降。桩长不等时,长短桩之间的相互作用效应并不一致,表现为两桩桩顶承受相同荷载时长桩沿桩身附加轴力增加较短桩明显。最后,将不等长桩相互作用系数应用于群桩的优化分析中,在保证总桩长和桩基沉降基本相当的情况下,通过调整不同位置的桩长使得各桩受力趋于合理。
[Abstract]:The Biot consolidation equation is used to decompose the pile-soil system under vertical load into half-space saturated expanded soil and virtual pile, respectively, taking equal-length and unequal-length piles as the analytical objects. The second kind of Fredholm integral equation of pile-soil interaction is established based on the vertical strain coordination relation, and the axial force distribution of pile under different consolidation conditions is solved. In the two piles of equal length, due to the existence of adjacent piles, the additional axial force is mainly distributed at the depth of 20% to 80% of the pile body, and its influence decreases with the increase of the pile spacing. Further extending the analysis of two piles of equal length to the study of pile group, the analysis shows that pile group effect causes the uneven distribution of pile top load, the consolidation of soil also has a certain effect on the internal force distribution of pile body, and the load borne by corner pile after consolidation decreases somewhat. When the pile length is unequal, the interaction effect between the long and short piles is not the same, which shows that the additional axial force of the long piles along the pile body increases obviously when the top of the two piles is subjected to the same load. Finally, the interaction coefficient of unequal length piles is applied to the optimization analysis of group piles. Under the condition that the total pile length is basically equal to the settlement of pile foundation, the stress of each pile tends to be reasonable by adjusting the pile length of different positions.
【作者单位】：同济大学岩土及地下工程教育部重点实验室;同济大学地下建筑与工程系;卧龙岗大学土木采矿与环境工程学院;
【基金】：国家自然科学基金项目(41172246) 国家重点基础研究发展计划(973计划)项目(2013CB036304)
【分类号】：TU473.1

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