Analyses On Stability Of Bored Piles And Research On It By Base Post-Grouting

The bored pile has been used widely because of its many virtues. Unfortunately, stability and carrying capacity of bored piles are affected by too many factors while used, some of which had not been studied systemically.Grouting quantity has not been taken into account comprehensively in the formulas of bearing capacity in criterions.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, those disadvantages will be overcome effectively. The formulas of bearing capacity are founded on the research on medium-short bored piles; while super-long and large-diameter bored piles have being used widely. So it is necessary to establish the formulas of those. Based on the analysis above, these problems had been refered below.1. The finish time of single pile has been put fotword, which influences stability and carrying capacity of bored piles largely. Although engineers have realized its importance, there is still only little research on it. It is analyzed in this paper theoretically so that others may come up with valuable opinions.2. By using cylindrical cavity expansion and More-Coulomb theory, the process of shrinkage of soil around wall of piles was analyzed after or while boring. Besides, to ensure the stability of piles, the equation of mud's specific gravity and stress of soil around bores has been deduced to provide theoretical base for construction.3. Grouting quantity's influence on bearing capacity has been embodied in the formulas of bearing capacity.4. The formulas of bearing capacity of bored pile by base post-grouting are founded on the research on medium-short bored piles, while super-long and large-diameter piles'capability of load bearing is different from it general. A great deal of data from example of engineering (or experimentation) have been collected in this paper, and then been concluded, transacted and summarized. Finally, this paper proposals experiential formula of super-long bored pile by base post-grouting. It's expected to be used in engineering by amending later.