自重湿陷性黄土地区桩基础承载特性研究

Research on Load Bearing Characteristics of Pile Foundation in Self-weight Collapsible Loess Region

文中依托西安某公路桥梁工程,采用有限元法,结合现场浸水载荷试验结果,在验证模型有效性的基础上,通过改变桩径及桩长,对比研究了桩周黄土产生湿陷和未产生湿陷两种情况下的桩基受力承载特性.结果表明:当桩长为20 m、桩径为0.8 m时,桩周土未湿陷时极限承载力为3 500 kN,桩周土湿陷时极限承载力为3 300 kN,承载力减小了5.71%.当桩长为17.5 m、桩径为1.2 m时,桩周土未湿陷时极限承载力为6 000 kN,桩周土湿陷时极限承载力为5 700 kN,承载力减小了5%.自重湿陷性黄土地区的桩基承载能力随有效桩长的增大而增大,且相较于增加桩长,增加桩径时承载力的提高幅度较大,且沉降量较小,表明自重湿陷性黄土地区增加桩径更有益于提高桩基础的承载力.

Relying on a highway bridge project in Xi’an,combined with the finite element method and the results of field immersion load test,on the basis of verifying the validity of the model,the bearing characteristics of pile foundation with and without collapse of loess around the pile were compared by changing the pile diameter and pile length.The results show that when the pile length is 20m and the pile diameter is 0.8m,the ultimate bearing capacity of the soil around the pile is 3500kN when it is not collapsed,and it is 3300kN when it is collapsed,and the bearing capacity is reduced by 5.71%.When the pile length is 17.5m and the pile diameter is 1.2m,the ultimate bearing capacity of the soil around the pile is 6000kN when it is not collapsed,and 5700kN when it is collapsed,which reduces the bearing capacity by 5%.The bearing capacity of pile foundation in self-weight collapsible loess area increases with the increase of effective pile length.Compared with increasing pile length,the bearing capacity of pile foundation is improved greatly with increasing pile diameter,and the settlement is smaller,which shows that increasing pile diameter in self-weight collapsible loess area is more beneficial to improve the bearing capacity of pile foundation.