软土地基刚性桩复合地基动力离心模型试验

采用离心机-振动台系统对饱和软土地基中连续地震作用下上部结构-性桩复合地基体系的抗震问题开展试验研究。试验分析了结构和基础模型在水平输入地震作用下的加速度、位移以及桩身应变等响应规律。结果表明,基础板与桩顶之间设置砂垫层利于削弱传递到上部结构的水平地震力作用,发生较大地震时能有效减小上部结构的加速度响应;地震结束时基础瞬时沉降随地震强度增加而增大,但震后长期再固结沉降随地震强度变化不大;受周围土体地震软化行为影响,群桩荷载分担比例在震后有所降低;桩身峰值弯矩沿桩长分布形式明显不同于传统桩基础,且弯矩峰值较常规桩基减小不少。

Dynamic Centrifuge Model Test of Composite Foundation with Rigid Pile in Soft Clay

Centrifuge-shaking table tests were performed to study the seismic response of superstructure-composite foundation with rigid pile system under continuous earthquakes in soft clay. The acceleration, displacement and pile strains of superstructure and foundation model under horizontal input earthquake were analyzed. Test results show that: the sand cushion between raft and piles can weaken the horizontal seismic forces transferred to the superstructure, and the acceleration response of superstructure will be reduced effectively under larger earthquake; the immediate settlement after earthquake is increased with earthquake intensity. However, the long-term consolidation settlement is little influenced by earthquake intensity. The load sharing ratio of pile group decreases after each earthquake due to soil softening. The maximum bending moment distribution is rather different from conventional pile foundation, and the maximum bending moments decrease remarkably compared with it under similar conditions.