MOE Key Laboratory of Coast Civil Structures and Safety

Tianjin, China

MOE Key Laboratory of Coast Civil Structures and Safety

Tianjin, China
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Zheng G.,Tianjin University | Zheng G.,MOE Key Laboratory of Coast Civil Structures and Safety | Zhang L.-M.,Tianjin University | Zhang L.-M.,MOE Key Laboratory of Coast Civil Structures and Safety | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

The measured data show that the distribution of shaft resistance of long and super long piles under vertical working load is quite different from the suggested one by Geddes' solution. The shaft resistance is first fully mobilized at the upper part of the long and super long piles under the working load. Based on the measured shaft resistance distribution of the long and super long piles, both the simplified bilinear and the trilinear patterns of the shaft resistance are suggested. The additional stress solutions of the bilinear and the trilinear distribution patterns are deduced by using the combination of Geddes' solution. The comparison between the solution of the proposed patterns and the Geddes' solution shows that the additional stress beneath the piles of the Geddes' solution is significantly greater than that of the proposed method. So the settlement ratio of Geddes' solution is greater than that of the proposed method and thus the Geddes' solution overestimates the interaction of group piles. Through the back analysis of case studies, it is found that the settlement predicted by the proposed method is closer to the measured one compared with that predicted by the Geddes' solution.


Liu Y.,Tianjin Urban Infrastructure Investment and Construction Co. | Zhang L.-M.,MOE Key Laboratory of Coast Civil Structures and Safety | Zheng G.,MOE Key Laboratory of Coast Civil Structures and Safety
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

Pile tip grouting has been widely adopted in engineering in recent years. However, the improvement effect on piles with different lengths is rarely studied. Based on the parameters verified by finite element of a project in Tianjin and considering the enhancement of grouting, the bearing capacity of piles with different lengths is analyzed. The finite element analysis shows that the ultimate load raises 25%~71% for single piles with length of 20~100 m after grouting. The improvement effect of grouting is very significant for short piles, while that for super-long piles is not the same as that for short piles especially on tip resistance. Tip grouting is propitious to the load transformation to the lower part of the pile, and it is also helpful for the exerting of the tip resistance and the shaft resistance of the lower part of the pile.

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