Research On Construction Technique And Working Mechanism Of Bored Pile By Base Post-Grouting

The bored pile is a chief type of foundations used in high building and bridge. Unfortunately, some drawbacks such as sedimentation on the bottom of piles and mud around the shaft arise from traditional construction technique of bored pile. With the use of base post-grouting which is an excellent technique due to its upgrading the behavior of bored pile and saving the engineering costs drastically , those disadvantages will be overcome. Whereupon, the study to construction technique and working mechanism of bored piles by base post-grouting should be valuable both in theory and in practice .At first, based on the investigation to plenty of concerned materials about the technique of post-grouting in domestic and abroad, the author gives a summary and optimum to construction technique of bored pile by base post-grouting. According to some practical examples, the influence factors on bearing capacity of bored pile by base post-grouting and the mechanism of its increment of bearing capacity are also analyzed. Secondly, proposal formula of bored pile by base post-grouting are proposed on the basis of the evaluation to the formulas which were represented by the reference materials. The proposal formula is proved credible by comparing the calculating results with the practical engineering results. At the same time, the research project of Sutong bridge across Yangtze River (《Research on construction technique of bored pile by base post-grouting of Sutong bridge 》)is also involved. In the first-peroid and second-peroid spot full-dimension test engineering of Sutong bridge across Yangtze River , "U" type grouting pipe was used and showed excellent behavior. At last, with the data of tests, the influences on bearing capacity of base and shaft of bored pile by base post-grouting are analyzed profoundly and the characteristics of big-diameter and super-long pile are obtained .