【作者】 李新坡；

【导师】 袁文忠；

【作者基本信息】 西南交通大学 ， 岩土工程， 2003， 硕士

【摘要】 本文针对深基坑排桩支护桩顶圈梁设计计算中存在的问题，以桩项圈梁的作用机理为主要研究内容，分别采用传统的结构力学矩阵计算方法和有限元分析软件对排桩—项圈梁支护体系内力进行计算和分析，对桩项圈梁作用的力学机理进行了深入的研究。在此基础上，作者对基坑排桩支护结构的优化设计作了进一步的探讨。 本文介绍了基坑支护的常用结构型式及适用条件和一些常规的支护结构内力计算方法等深基坑工程的常规问题；建立了一种考虑圈梁作用的计算模型，并对具体的实例进行了计算，结果比较合理；通过对计算结果的比较和分析，对桩顶圈梁作用的力学机理进行了深入探讨；采用目前比较流行的大型有限元分析软件ANSYS对算例进行了分析计算，结果与常规计算方法的结果相符；对复合形优化计算方法用于深基坑排桩支护作了介绍，建立了悬臂桩-顶圈梁支护体系优化计算数学模型，并对一个实例进行了优化设计计算。 桩顶圈梁对支护桩的作用主要体现在：改善支护桩的力学性状，变悬臂桩为顶端约束的超静定状态；对桩顶位移起限制作用，减小基坑工程对周边环境的不良影响；协调各桩之间的受力和位移，避免局部受力过大引起各桩之间的连锁破坏现象。在闭合状态下，圈梁发挥作用主要依赖基坑转角处的支顶和自身刚度；圈梁两端自由时，圈梁作用仅限于对各桩之间力和变形的协调。对于考虑桩项圈梁作用的深基坑排桩支护优化设计，复合形法可以取得比较好的效果。更多还原

【Abstract】 Study on the mechanism of the top beam that used in retaining and protecting piles of deep foundations is the uppermost section of this master degree thesis. The classical structure mechanics method and the finite elements analysis software are used to calculate and analyse the internal force of the piles-top beam retaining system. Based on the research of the mechanism of the top beam, the optimal design of piles in row is discussed.The retaining structure types used in deep foundation and these effective conditions, calculation methods of the internal force of retaining structure are reviewed in the paper. As the same time, a model for the calculation of top beam is Cstnblished and used successfully in an engineering instance. The mechanics mechanism of lop beam is discussed by the mcthod of comparing and analyzing the results of calculation. The engineering instance is calculated by ANSYS, the popular software for the finite elements analysis, and the results is same as that calculated by common method. The complex method is introduced and a math model for optimal design is successfully established to design a deep foundation’s retaining system in an instance.The top beam can reform the force-bearing mechanism of the retaining piles because the cantilever piles can be fixed by adding a restriction on the top of the piles and the displacement of the piles can be reduced too. As the same time, top beam can harmonize the displacement and force of the piles and avoid the phenomenon of chain failure as one of the piles is destroyed. If the top beam are closed it can work well because the support on the two ends. If the two ends of the top beam are all free it can only harmonize the displacement and force of the piles. The complex method can work well in the calculation of piles optimal design.更多还原