喷扩锥台压灌桩最优构造

根据喷扩锥台压灌桩现场试验结果，运用Abaqus软件建立试验数值模型，得到竖向荷载作用下锥台扩径体(下称锥台)对周边土体的影响规律：明确锥台下2D~3D(D为锥台直径)范围土体有挤压作用，锥台下0.5 m处达到极限；锥台上部土体出现应力松弛，在锥台顶部达到极限，影响范围上延1.25D；水平影响范围为1.5D~2.5D；锥台最优喷扩角度为50°~55°；最优扩径比为2~2.75；最优位置为桩端上部D~2D；定喷翼板至桩顶下7~8 m时最佳。最优构造模型可提高承载力19%，建议采用最优构造桩型进一步提高效益，促进该桩应用。

Optimal structure of pressure cast-situ-pile with spray-expanded frustum

According to the field test results of pressure cast-situ-pile with spray-expanded frustum, with the help of Abaqus to establish the numerical model of the experiment, the influence rule of expanded body with frustum (hereinafter referred to as frustum) on surrounding soil under vertical load was obtained. It was clarified that the soil mass had squeezing effect within the 2D~3D range (D is frustum's diameter) and it reached the limit at 0.5 m under the frustum. Stress relaxation occured in the upper soil of frustum, which reached the limit value at the top of the frustum, and of which the vertical influence range was extended by 1.25D and the horizontal influence range was 1.5D~2.5D. Revealed that the optimal spray angle for frustum expanding was 50°~55°, the optimum expanding ratio was 2~2.75, the optimal position was in the D~2D range of upper part of pile, and it was optimal when the fixed spray wing was 7~8 m below the pile top. The optimal construction model could increase the bearing capacity by 19%, therefore it was suggested to adopt the optimal structural pile type to further improve efficiency and promote application of the pile.