Field study of set-up effect in open-ended PHC pipe piles |
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| Authors: | Hai-Lei Kou Wei Guo Ming-Yi Zhang |
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| Institution: | 1. School of Civil Engineering and Architecture, Weifang University, Weifang, China;2. School of Civil and Environmental Engineering, Nanyang Technological University, Jurong, Singaporekou123321@126.com;4. School of Civil and Environmental Engineering, Nanyang Technological University, Jurong, Singapore;5. Institute of Geotechnical Engineering, Qingdao Technological University, Qingdao, China |
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| Abstract: | Large-scale field tests were conducted to study set-up effect in open-ended prestressed high-strength concrete pipe piles jacked into stratified soil. Four open-ended prestressed high-strength concrete pipe piles with 13 and 18 m in embedment depth were fully instrumented with fiber Bragg grating sensors and installed. Several restrike dynamic tests were performed on each test pile, with the time interval from 21.5 to 284 hours after installation. Static loading tests (SLTs) were later performed on each test pile at 408 hours after installation to substantiate the dynamic tests. Changes with time in pile bearing capacity and in the shaft and toe resistances were studied based on the results of the pile tests. The development of shaft resistance set-up in different layers was studied in particular. It was found that set-up effect in the shaft resistance is significant and the toe resistance increment was minor. The overall set-up factor of total bearing capacity was found to range from 0.09 to 0.53, and the set-up effect of friction pile is much larger than the end bearing pile. More significant set-up in shaft resistance was observed in fill and alluvium layer. The dimensionless set-up factor A for shaft resistance in marine deposits ranges from 0.5 to 1.43, and it contributes the most to the shaft resistance as the shaft resistance in marine deposits is higher. |
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| Keywords: | FBG sensors open-ended PHC pipe pile set-up factor shaft resistance toe resistance |
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