Research on the Influence of Foundation Pit Excavation on the Vertical Bearing Characteristics of Pipe Piles
In view of the weakening of the soil squeezing effect caused by the foundation pit excavation and the influence of the this weakening on bearing characteristics of the pipe piles,indoor model experiments have been conducted,with the reliability of the numerical model verified through numerical modeling of the model experiment,followed by a study on the influence of pile length,pile spacing,and pile lateral friction coefficient on the bearing characteristics of pile foundations under excavation unloading on the former basis.The results show that excavation unloading has a significant influence on the bearing characteristics of pipe piles,with the ultimate bearing capacity corresponding to a 54.5%increase in pile top settlement.Numerical calculations have found that the maximum settlement difference rate is 9.52%corresponding to the ultimate load before and after unloading,which meets the engineering accuracy requirements,thus verifying the reliability of the proposed numerical model.The numerical calculation results show that as the pile length increases,the maximum axial force position of the pile body keeps rising,while the neutral point position continues to decline.The smaller the distance between piles,the greater the influence of excavation and unloading on the axial force of the pile body,and the smaller the influence on negative frictional resistance.With the friction coefficient being 0.3,the sensitivity of the friction coefficient to the axial force of the pile body and the lateral friction of the pile reaches the highest point.
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