桩-承台-土复合受力体的拟静力模型试验

在1.2 m×1.2 m×1.2 m小型土工箱中完成了4组采取不同桩头连接构造的单桩-承台-土复合受力体缩尺模型的低周往复水平加载抗震试验，获得了试件破坏形态、荷载-位移滞回曲线、刚度退化曲线、桩身弯矩及桩侧土压力等数据，研究了不同桩头连接构造对试件水平受力性能的影响。研究表明：桩头部位采取不同的节点连接构造措施对桩头破坏形态和破坏程度、体系耗能能力和水平极限承载力及桩身弯矩分布规律均有一定的影响，但对桩与承台侧面的土压力分布规律和大小的影响并不显著。对于桩头普通连接的情况，以桩头嵌入深度为0.5D（D为桩径）为宜。桩头加强环连接与桩头嵌入深度1.0D时的连接具有大体相当的桩头约束效果，但加强环的制作相对复杂，其约束效果和破坏形态与加强环的截面尺寸、混凝土强度及配筋参数均有关系，应进一步深入研究。

Pseudo-static model experiment of pile-cap-soil system

This study investigated pile-cap-soil system considering different connection details in four pseudo-static seismic tests using a 1.2 m×1.2 m×1.2m mini-soil box. The failure modes, hysteretic performance, stiffness degradation, moment of pile and soil pressure were observed. Effects of the different pile-cap connections on the seismic performance were studied. The research shows that the different connections obviously influence the pattern and degree of failure of the pile head, the energy dissipation of the system, the level of ultimate bearing capacity, and the distribution of pile bending moment. However, the distribution and magnitude of soil pressures on cap sides and pile are not influenced by the connection types. For common connections, it is optimum that pile head is directly embedded in pile cap by 0.5D. When the strengthen ring connection is adopted, the restraint effect of the strengthen ring connection is roughly the same as that of common connections (embedded depth is 1.0D). Obviously, the construction of the strengthen ring connection is complicated, the restraint effect and damage form of the strengthen ring connection are related to the section, the strength of concrete and reinforcement of strengthen ring. The further works will be needed to analyze these parameters.