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介绍了伞式扩底抗拔桩这一新的抗拔桩形式,该抗拔桩可通过地面操作使预制构件在桩基持力层中完成扩底施工,扩底幅度不受限制。在工程试验与工程应用的基础上,研究了伞式扩底抗拔桩的承载机理,提出冲剪破坏、局部剪切破坏与整体剪切破坏三种承载破坏模式,给出了承载力计算方法,并结合足尺试验进行验证。在本文介绍的足尺试验中,桩身直径为0.35 m,在18 m深度以下的扩底直径达到了2.172 m,为桩身直径的6~7倍,大幅度提高了单桩抗拔承载力。试验结果表明,承载力计算结果与实测值接近,可为工程应用及扩底抗拔桩承载机理的研究提供参考。
The new type of uplift piles with umbrella - type enlarged bottom uplift piles is introduced. The uplift piles can be expanded in the pile holding layer by ground operation, and the enlargement of bottom expansion rate is not limited. On the basis of engineering test and engineering application, the bearing mechanism of U-shaped U-shaped pile is studied, and three kinds of bearing failure modes of punching shear failure, local shear failure and integral shear failure are proposed. The calculation method of bearing capacity , And combined with full-scale test to verify. In the full scale test presented in this paper, the pile diameter is 0.35 m, and the diameter of the expanded bottom below 18 m reaches 2.172 m, which is 6 to 7 times of the diameter of the pile, which greatly improves the pull-out bearing capacity . The test results show that the calculated result of bearing capacity is close to the measured value, which can provide reference for the engineering application and the research on the bearing mechanism of expanded upright piles.