Test Research On Super-long Bored Pile In Sofe Clay

Based on comparison of static loading test and axial force test result of pile with (AS4) or without (AS2) grouting in bottom, mechanism of load transferring and load bearing behavior of the super-long bored pile in the soft clay area is discussed. The results show that, its load bearing capacity could grow rapidly and increase up to 59.5% if the pile had been grouted in bottom. The side friction resistance is dominated in case of super-long bored piles in the soft clay area. In this example, 99% loads level is the side friction resistance and the bottom resistance is neglected. The side friction resistance increases with displacement between pile and soil before it reaches ultimate level and this process can be described by elastic-plastic model. The bottom resistance begins to act on pile before the side friction resistance reaches ultimate level because the soil around pile is compressed. The result of the load bearing behavior of AS2 pile without grouting in bottom shows that the bottom resistance would affect early if the bottom soil of pile is weak. Although the bottom resistance occupies a small part of loads level, it is very important to assure the side friction resistance. The side friction resistance decreased with the bottom resistance decrease. Thus the bottom resistance shouldn't be ignored.