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Geomechanics and Engineering
  Volume 13, Number 6, December 2017, pages 929-946
DOI: https://doi.org/10.12989/gae.2017.13.6.929
 


Calculation models and stability of composite foundation treated with compaction piles
Xuansheng Cheng and Wei Jing

 
Abstract
    Composite foundation treated with compaction piles can eliminate collapsibility and improve the bearing capacity of foundation in loess area. However, the large number of piles in the composite foundation leads to difficulties in the analysis of such type of engineering works. This paper proposes two simplified methods to quantify the stability of composite foundation treated with a large number of compaction piles. The first method is based on the principle of making the area replacement ratios of the simplified model as the same time as the practical engineering situation. Then, discrete piles arranged in a triangular shape can be simplified in the model where the annular piles and compacted soil are arranged alternately. The second method implements equivalent continuous treatment in the pile-soil area and makes the whole treated region equivalent to a type of composite material. Both methods have been verified using treated foundation of an oil storage tank. The results have shown that the differences in the settlement values obtained from the water filled test in the field and those calculated by the two simplified methods are negligible. Using stability analysis, the difference ratios of the static and dynamic safety factors of the composite foundation treated with compaction piles calculated by these two simplified methods are found to be 3.56% and 5.32%, respectively. At the same time, both static and dynamic safety factors are larger than the general safety factor, which should be greater than or equal to 2.0 according to the provisions in civil engineering. This indicates that after being treated with compaction piles, the bearing capacity of the composite foundation is effectively improved and the foundation has enough safety reserve.
 
Key Words
    composite foundation; compaction piles; stability; safety factor; soil-structure interaction
 
Address
Xuansheng Cheng and Wei Jing: 1.) Key Laboratory of Disaster Prevention and Mitigation in Civil Engineering of Gansu Province, Lanzhou University of Technology, Lanzhou, 730050, China

2.) Western Engineering Research Center of Disaster Mitigation in Civil Engineering of Ministry of Education, Lanzhou University of Technology, Lanzhou, 730050, China
 

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