饱和黏性土中散体桩复合地基极限承载力系数研究

发布时间：2018-01-13 01:25

本文关键词：饱和黏性土中散体桩复合地基极限承载力系数研究　出处：《岩土工程学报》2015年03期 　论文类型：期刊论文

【摘要】：埋置深度对复合地基承载力的影响规律一直缺乏深入研究,工程中采取最低程度考虑基础埋深的保守方法导致复合地基承载力被不同程度的低估。采用有限差分法建立饱和黏土中散体桩复合地基数值模型,对刚性基础下散体桩变形模式及机理进行分析,在此基础上,进行考虑桩、土为无重介质的散体桩复合地基极限承载力系数研究。结果表明散体桩复合地基破坏模式受置换率、桩长和埋深耦合作用,可能发生浅基础型、复合型或实体基础类型的破坏模式。深度修正系数随着桩长的增加而增大,随埋深的增加而减小;当桩长和埋深一定时,存在一个最优置换率使深度修正系数取得极大值。而现行规范中深度修正系数取1.0,低估了基础埋深的作用。最后基于M o h r C o u l o m b破坏准则推导群桩复合地基的等效强度,并利用极限分析法推导了浅基础破坏模式下复合地基的极限承载力系数解答,结果与有限差分法的结果吻合较好。
[Abstract]:The influence of buried depth on the bearing capacity of composite foundation has been lack of in-depth study. The conservative method of considering the depth of foundation at the lowest level in engineering causes the bearing capacity of composite foundation to be underestimated to varying degrees. The finite difference method is used to establish the numerical model of composite foundation with scattered piles in saturated clay. The deformation mode and mechanism of the pile under rigid foundation are analyzed, and the pile is considered on this basis. The study on ultimate bearing capacity coefficient of composite foundation with loose pile without heavy medium shows that the failure mode of composite foundation with bulk pile may be of shallow foundation type due to the interaction of replacement rate, pile length and buried depth. The depth correction coefficient increases with the increase of pile length and decreases with the increase of buried depth. When the pile length and buried depth are fixed, there is an optimal replacement rate to maximize the depth correction coefficient, while the depth correction coefficient is 1.0 in the current code. The effect of foundation depth is underestimated. Finally, the equivalent strength of pile group composite foundation is derived based on the failure criterion of M o h r and C o u o m b. The ultimate bearing capacity coefficient solution of the composite foundation under the failure mode of shallow foundation is derived by using the limit analysis method. The results are in good agreement with the results obtained by the finite difference method.
【作者单位】：天津大学建筑工程学院;滨海土木工程结构与安全教育部重点实验室(天津大学);天津大学水利工程仿真与安全国家重点实验室(天津大学);
【基金】：国家自然科学基金项目(51378345)
【分类号】：TU473.1
【正文快照】： U n i v e r s i t y),M i n i s t r y o f E d u c a t i o n,T i a n j i n 3 0 0 0 7 2,C h i n a;3 S t a t e K e y L a b o r a t o r y o f H y d r a u l i c E n g i n e e r i n g S i m u l a t i o n a n d S a f e t y(T i a n j i n U n i v e r s i t y),T i

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