Effect Of Tunneling On Load Transfer And Deformation Of Piles With Different Friction Distributions

The metro tunnel usually constructed in congested urban area,invieatable affecting the pile of buildings.At present,the effect of tunnel excavation on piles has attracted attention.However,existing researches have not considered pile-soil interface stress history caused by pile construction.Therefore,this paper conducted the research on this problem.Based Mindlin solution and hypoplastic pile-soil interface,this paper used Matlab to develop a simplified algorithm for pile-soil interaction and load transfer.The pile load-displacement curve obtaine d by the centrifuge test in the existing literature is selected to verify accuracy of he algorithm.Effects of excavation and the pile installation on shaft resistance distribution are considered.Finally,the soil displacement field caused by tunnel excavation based on the Loganathan-Poulos solution is considered.The effects of tunnel excavation on load transfer and settlement of the engineering pile is studied with considering the stress history of the pile-soil interface.Algorithm is used to study effects of the side and undercrossing tunnel excavation on load transfer and deformation when compressive or uplift load is applied to pile head with and without considering excavation effect.Algorithm is also used to study effects of the side and undercrossing tunnel excavation on load transfer and deformation when compressive load is applied to pile head with and without installation effect.parameters of the pile length,tunnel depth and different pile-soil interface were analyzed.Pile applied by compressive load is studied firstly.Considering effects of excavation,shaft resistance in the upper part caused by tunnel excavation is almost zero.The settlement of the pile caused by tunnel excavation is significantly larger than that without considering the excavation.As the pile length and the buried depth of the tunnel increases,the pile head settlement caused by the side tunnel increases firstly and then decreases,and pile head settlement caused by undercrossing tunnel excavation increases gradually.Compared to the displacement of pile with the hyperbola interface,the displacement of pile with the hypoplastic interface caused by the side and undercrossing tunnel is larger.Then pile applied by uplift load is studied.The settlement of the pile with considering excavation effect caused by tunnel excavation is close to or little smaller that without considering excavation effect.With the increase of the pile length and the buried depth of the tunnel,the pile head settlement caused by the side tunnel increases firstly and then decreases,and pile head settlement caused by undercrossing tunnel excavation increases gradually.When hyperbola interface is adopted,the displacement of the pile caused by tunnel excavation with considering excavation effect is greater than that without considering excavation effect.This is contrary to the application of the hypoplastic interface.The driven pile applied by compressive load is studied finally.Shaft resistance and pile head settlement caused by tunnel excavation with considering installation effect are larger than that without considering installation effect.As the pile length and the buried depth of the tunnel increases,the pile head settlement caused by the side tunnel excavation and undercrossing tunnel excavation decreases gradually.When the hypoplastic nterface is adopted,the displacement of the pile caused by tunnel excavation with considering installation effect is greater than that without considering installation effect.When the hyperbola interface is adopted,the displacement of the pile caused by tunnel excavation with considering installation effect is close to that without considering installation effect.