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A platform for research: civil engineering, architecture and urbanism
1g model tests of piled-raft foundation subjected to high-frequency vertical vibration loads
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.
Highlights 1 g model tests were conducted to examine the effects of vibration loads on piled-raft foundation (PRF) in the different sandy grounds. For dry loose sandy ground, the vibration frequency of loading significantly affected the settlement of the PRF. The cement-treated partial ground improvement can reduce the acceleration response and settlement of the PRF. The load-sharing ratio of pile friction decreased after the vibration, while the ratio of pile tip resistance increased. Extensive precaution should be taken in designing PRF for soft ground.
1g model tests of piled-raft foundation subjected to high-frequency vertical vibration loads
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.
Highlights 1 g model tests were conducted to examine the effects of vibration loads on piled-raft foundation (PRF) in the different sandy grounds. For dry loose sandy ground, the vibration frequency of loading significantly affected the settlement of the PRF. The cement-treated partial ground improvement can reduce the acceleration response and settlement of the PRF. The load-sharing ratio of pile friction decreased after the vibration, while the ratio of pile tip resistance increased. Extensive precaution should be taken in designing PRF for soft ground.
1g model tests of piled-raft foundation subjected to high-frequency vertical vibration loads
Zhu, Wenxuan (author) / Gu, Linlin (author) / Mei, Sen (author) / Nagasaki, Koki (author) / Chino, Nobuaki (author) / Zhang, Feng (author)
2020-10-24
Article (Journal)
Electronic Resource
English
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