Model test on bearing characteristics of long-span pile foundation of collapsible loess foundation
The long-span pile foundation in the development project of the superstructure of the urban depot has the characteristics of larger vertical bearing of a single pile,and the soil within the large span between the piles is lesser stressed.Taking the long-span pile foundation of a depot of Xi'an Metro as the research object,artificial collapsible loess is prepared as a similar material.An indoor model test of long-span pile foundation in collapsible loess layer was carried out.The load transfer mechanism and deformation law of long-span pile foundation in collapsible loess layer were studied.The results show that the prepared artificial collapsible loess is close in nature to the original loess on site,which can achieve good results in the application of model tests.When the long-span pile foundation is not flooded,the load-settlement curve is steep,and the axial force of the pile body decreases significantly near the top of the pile.When the ultimate bearing capacity is not reached,the pile top settles and the pile end resistance increases linearly.After the loess is flooded,the axial force of the pile body is distributed in a"D"shape along the direction of burial depth.With the increase of water immersion time,the pile top settlement and pile end resistance first slowly increased and then increased significantly,and the neutral point position continued to move to the lower part of the pile body.
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