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利用ANSYS/LS-DYNA通过锤击法对打桩过程中桩锤冲击桩顶之后的动力过程及桩身内的动态应力场分布进行分析。建模过程中对于桩端打到坚硬土层的情形,考虑到了桩端几乎不能下沉,因此桩端采用固定端的实际约束方式。对于桩端打到软的淤泥层中的情形,土层对桩端的位移形成阻碍可以忽略不计,此时桩端可采用自由端。而实际情况必然介于这两者之间,通过本文的分析研究对于施工中的打桩提供了很好的科学依据,分析发现在自由端的情况下,靠近桩底部的一段将承受较大的拉应力,很好的符合了对于抗拉强度不高的混凝土桩来说出现断桩的现象,这在工程的施工中是非常需要注意的问题。
The dynamic process and the distribution of dynamic stress field in the pile body after pile hammer striking pile top during piling process were analyzed by hammering method with ANSYS / LS-DYNA. In the modeling process, when the pile end hit a hard soil layer, considering that the pile tip can hardly sink, the pile end adopts the actual restraint method of the fixed end. For the case where the pile tip is hit into a soft silt layer, the formation of the soil layer hinders the displacement of the pile end to be negligible. In this case, the free end of the pile end may be adopted. However, the actual situation inevitably lies between the two. Through the analysis and research in this paper, it provides a good scientific basis for the piling in construction. The analysis shows that at the free end, the section close to the bottom of the pile will bear greater tensile stress , Which is in good agreement with the phenomenon of broken stakes in concrete piles with low tensile strength. This is a problem that needs attention in the construction of the project.