Model tests on vertical bearing capacity of super-long pile groups in clay

According to the current situation of super-long pile groups,i.e.more application and less theoretical studies,a large-scale laboratory model test is conducted.By the model test and data analysis of super-long bored pile group with 6d pile spacing in clay,the load transfer mechanism and bearing capacity behaviors are studied.The load-settlement curve,the proportion between pile compression and pile top settlement,the distribution of axial force and lateral frictional resistance under vertical loads are obtained.The results show that the basic piles in the super-long pile groups are non-rigid friction piles,and the pile top settlement is mainly induced by pile compression;under the ultimate load,the pile tip resistance is close to zero and the lateral frictional resistance in the middle-lower part is not fully utilized.These conclusions can provide a useful guidance for the theoretical researches,engineering design and construction of super-long pile groups.