Abstract The piled-raft foundation (PRF) has been used in high-speed railway in China. If the design and construction of the foundation is done without taking proper precautions, then the vibration loads induced by the high speed trains may cause excessive settlement of the foundation, significantly affecting the stability and safety of trains. To carefully examine the settlement mechanisms of PRFs constructed in different grounds subjected train loads, systematic 1 g model tests were conducted. The dynamic responses of PRFs in dry loose sand, medium dense sand, and saturated medium dense sand ground, subjected to different frequencies of sinusoidal vibration loads, were investigated. Additionally, reinforcement effect of cement-treated partial ground improvement (PGI) for dry loose sand ground, a commonly used countermeasure against settlement of PRF, was also investigated via model tests. It is found that the dynamic loading frequency affected the settlement of PRF, and the pattern of PGI reinforced at different depths of pile also significantly affected the settlement. The model test also showed that load-sharing ratio between pile and raft also changed significantly during vibration loading, implying that extensive precaution should be taken in design and construction of PRFs for high-speed railway constructed in soft ground.

中文翻译：

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高频竖向振动荷载作用下桩筏基础1g模型试验

摘要 桩筏基础（PRF）已在我国高速铁路上得到应用。如果基础的设计和施工没有采取适当的预防措施，那么高速列车引起的振动载荷可能会导致基础过度沉降，严重影响列车的稳定性和安全性。为了仔细检查在不同地面上建造的 PRF 承受列车载荷的沉降机制，进行了系统的 1 g 模型测试。研究了在不同频率的正弦振动载荷作用下，PRFs 在干燥松散砂、中密砂和饱和中密砂地基中的动力响应。此外，水泥处理的局部地基改良（PGI）对干燥松散沙地的加固效果，还通过模型试验研究了一种常用的防止 PRF 沉降的对策。研究发现，动荷载频率对PRF的沉降有影响，不同桩深PGI的加固方式对沉降也有显着影响。模型试验还表明，在振动加载过程中，桩与筏之间的荷载分担比也发生了显着变化，这意味着在软土地基上建造的高速铁路PRF的设计和施工中应采取广泛的预防措施。