Abstract: In recent years, the number of large-area filling sites projects have been greatly increased in China. This can alleviate contradictions between supply and demand of construction lands. However, it also gives rise to many engineering problems. For example, subsidence of large area site increases negative skin friction(NSF) on pile shaft, which affects the pile safety. However, there have been limit studies on NSF of frictional piles occur in large area filling sites. Based on a field test, a single pile finite element analysis model is established, and the rationality of the model is verified by comparing with the measured data. Based on the verified numerical model, influences of weight and thickness of fill, load on pile head, surcharge loading and field consolidation time on skin friction of a single frictional pile are studied. The results show that fill thickness and load on pile head play major influences on neutral point position. An increased negative frictional force is associated with an increase in thickness and weight of fill, and a reduction in fill consolidation time. It is also linked to a reduction of load on pile head and increase in surcharge. Sensitivity analysis show that factors related to fill formation play a more significant role in NSF of pile shaft than the loading factors. The applicability of the common design methods used at home and overseas, calculating the NSF of frictional pile in large filling sites is discussed. The results can provide guidance for engineering application of frictional pile in large filling sites.

Key words: frictional pile, negative friction, site formation, finite element analysis, soft clay