上拔荷载作用下桩–桶基础结构 尺寸效应的数值分析

 运用ABAQUS软件分析不同尺寸的桩–桶基础在相同上拔位移时的上拔荷载及基础周围地基土体影响区域的变化，并对桩–桶基础进行初步设计。桩–桶基础的主要尺寸包括桶顶以下入土桩长(L3)、桶半径(R)及桶壁高(H)，不同尺寸的桩–桶基础在地基土体达到破坏时的极限荷载各不相同，增加L3，R及H能提高基础的抗拔承载力，同时地基土体的影响范围也随之加大；R的变化对基础的抗拔承载力影响最大，其次是L3的变化，最后是H的变化；影响地基土体横向范围的结构尺寸主要是R，L3次之，H最小；影响地基土体的纵向范围的结构尺寸主要是L3，H次之，R最小。L3∶R = 8.0∶1.0时，能充分体现桩结构和桶结构共同的抗拔承载性能；R∶H = 0.6∶1.0时能充分体现桶结构的抗拔承载性能。

NUMERICAL ANALYSIS OF SCALE EFFECT OF PILE-BUCKET FOUNDATION STRUCTURES UNDER UPLIFT LOADING

The ABAQUS software was used to research the uplift loading and the affected region of ground soil body on pile-bucket foundations of different sizes under same uplift displacement，and preliminary design of pile-bucket foundation was carried out. The sizes of pile-bucket foundation mainly included the pile length under the top of the bucket(L3)，the bucket radius(R) and the bucket wall height(H). The ultimate uplift loading of pile-bucket foundations are various with change of size of foundations. The scope influenced by the uplift bearing capacity of foundation and ground soil body could be highly enhanced if L3，R and H were increased; the influence of change R was most to the uplift bearing capacity of foundation and the ground soil body horizontal scope，and the change of L3 took the second place，and the change of H went the last；the influence of change L3 was most to the ground soil body longitudinal scope，and followed by the change of H and R. When the proportion relation of L3 and R reached 8.0∶1.0，common uplift performance of the pile structure and the bucket structure together could be fully manifest; when the proportion relation of R and H was 0.6∶1.0，the uplift performance of the bucket structure was embodied completely.