非对称埋深下条形基础地基承载力研究

发布时间：2018-09-12 19:13

【摘要】：地基基础是建筑物的根基,必须保证足够的承载能力和稳定性。工程上计算地基承载力通常采用普朗特地基承载力公式出发进行修正的方法,但对于非对称超载作用下条形基础地基极限承载力的计算并不适用,现行规范有明确的计算公式,但是简化为对称超载作用进行计算的。因此开展适合非对称埋深地基工程特点的破坏模式和承载力计算方法研究,具有重要的理论意义和工程实践意义。本文的主要工作和结论如下:(1)首先回顾了国内外地基承载力计算的发展和研究现状,介绍了地基极限承载力和地基破坏模式的基本概念,推导了经典地基极限承载力的计算方法,为进一步计算非对称埋深作用地基极限承载力奠定理论基础。(2)采用极限平衡分析方法对非对称埋深条形基础地基的极限承载力进行研究。结合条形基础破坏机理,借鉴对称埋深地基破坏模式,考虑非对称埋深作用下地基破坏的非对称性,构建出非对称埋深条形基础地基的合理破坏模型。通过该模型上受力分析,采用极限平衡分析方法,分别计算仅考虑基础埋深、土的黏聚力影响下地基极限承载力公式和仅考虑土体自重影响下地基极限承载力公式,综合两个公式,推导出非对称埋深作用并考虑土重的条形基础地基极限承载力计算方法。通过案例分析,得出条形基础在非对称埋深下承载力系数随一侧埋深的增加而变小,但地基极限承载力随两侧埋深之和的增加而增大。(3)采用有限元分析软件PLAXIS对非对称埋深地基破坏形状和承载力进行数值分析,分析基础两侧在不同埋深下地基的变形网格和极限承载力的变化,并与理论计算结果进行了比较与讨论。数值模拟所得地基极限承载力变化规律与理论计算结果规律基本一致。
[Abstract]:The foundation is the foundation of the building, it must ensure sufficient bearing capacity and stability. The formula of Plantt foundation bearing capacity is usually used to modify the foundation bearing capacity in engineering, but it is not applicable to the calculation of ultimate bearing capacity of strip foundation under asymmetric overload, and the current code has a clear formula for calculating the ultimate bearing capacity of strip foundation. But the calculation is simplified to symmetric overload action. Therefore, it is of great theoretical and practical significance to study the failure mode and bearing capacity calculation method suitable for the characteristics of asymmetric buried foundation engineering. The main work and conclusions are as follows: (1) the development and research status of foundation bearing capacity at home and abroad are reviewed, and the basic concepts of ultimate bearing capacity and failure mode of foundation are introduced. The calculation method of the ultimate bearing capacity of the foundation is deduced. It lays a theoretical foundation for further calculation of ultimate bearing capacity of asymmetric buried deep foundation. (2) the ultimate bearing capacity of asymmetric buried deep strip foundation is studied by using limit equilibrium analysis method. Based on the failure mechanism of strip foundation and the failure mode of symmetrical buried deep foundation and considering the asymmetry of foundation failure under asymmetric buried depth, a reasonable failure model of asymmetric buried deep strip foundation is established. Through the stress analysis on the model and the limit equilibrium analysis method, the formula of ultimate bearing capacity of foundation considering only the depth of foundation and the cohesive force of soil is calculated, and the formula of ultimate bearing capacity of foundation considering only the influence of soil gravity is calculated. Based on two formulas, the calculation method of ultimate bearing capacity of strip foundation considering soil weight and asymmetric burying depth is deduced. Through the case analysis, it is concluded that the bearing capacity coefficient of strip foundation decreases with the increase of the depth of one side under asymmetric burying depth. However, the ultimate bearing capacity increases with the increase of the sum of buried depth on both sides. (3) numerical analysis of failure shape and bearing capacity of asymmetric buried foundation is carried out by using finite element analysis software PLAXIS. The variation of deformation mesh and ultimate bearing capacity of both sides of the foundation under different buried depths are analyzed and compared with the theoretical calculation results. The variation law of ultimate bearing capacity obtained by numerical simulation is basically consistent with the law of theoretical calculation.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU470

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