不同振动波形对单桩桩-筏复合地基动力响应特性研究

桩-筏复合地基是控制高速铁路等路基工后沉降的一种常用地基处理技术，然而针对其在不同振动波形荷载下的动力响应特性对比研究相对较少。基于大型模型系统，开展砂土地基中单桩桩-筏复合地基大比例模型试验研究，着重分析不同振动波形加载下单桩桩-筏复合地基的累积沉降、桩底-桩侧土动土应力比、加速度及速度传递等变化规律，初步探讨振动波形对单桩桩-筏复合地基承载特性的影响机制。试验结果表明，M波振动波形对地基累积沉降的影响较正弦波振动波形对地基累积沉降的影响略大一些，对桩底-桩侧土动应力比的影响则反之；振动响应加速度和速度随着加载频率及振幅幅值的增大而增大。相关研究成果可为单桩桩-筏复合地基的理论分析与计算提供参考依据。

Dynamic response of single pile-raft composite foundation influenced by different waveforms

Pile-raft composite foundation is one of traditional soft ground treatment methods for embankment (such as high-speed railway embankment, etc.) settlement control. However, the researches focused on dynamic responses influenced by different vibration waveform loads are relative little. Large-scale model tests on single pile-raft composite foundation in sand are carried out. The accumulated settlement, pile end and pile side soil dynamic stress ratio, acceleration and speed are measured; and the mechanisms of pile-raft composite foundation influenced by vibration waveforms are briefly discussed and analyzed. The test results show that the accumulated settlement influenced by the M wave is slightly larger than that influenced by the sine wave; while the pile end and pile side soil dynamic stress ratio influenced by the M wave is slightly smaller than that influenced by the sine wave. The acceleration and speed along the pile-raft system are increased with the increasing of loading frequency and loading amplitude. The related research results provide a reference for the theoretical analysis and calculation of pile-raft composite foundation.