桩靴对饱和粉土中锤击管桩沉贯阻力的影响

Effects of Pile Shoe on Sinking Resistance of Hammered Pipe Pile in Saturated Silt Soil

带桩靴管桩有利于提高打入桩的贯入效率,并且会改变桩身荷载传递规律减小桩身破损。为探究饱和粉土中开口管桩锤击沉贯机理,对双壁开口模型桩进行了室内贯入试验。锤击沉桩下考虑不同桩靴形式的影响,采集沉桩过程中桩身应变和土塞变化。研究发现,沉桩进入硬质砂土层后沉桩阻力明显增大,桩端阻力占比较大,桩靴能有效减小沉桩阻力;在同一土层位置处,外侧摩阻力会出现衰退现象,内倾30°桩靴桩内单位侧摩阻最大;桩端形式对土塞影响显著,沉桩结束时土塞率内倾30°桩靴试桩、外倾30°桩靴试桩、无桩靴试桩分别为41%、35%和31%。桩靴可有效降低穿越硬质土层的贯入阻力,研究结论可用于指导打入桩施工,为预制管桩打入过程选用合适的桩靴形式提供参考。

Pile with pile shoe pipe pile is beneficial to improve the penetration efficiency of the driven pile,and will change the load transfer law of the pile body and reduce the pile body breakage.In order to explore the hammering and sinking mechanism of open pipe piles in saturated silt,an indoor penetration test was carried out on double-walled open pipe piles.The influence of different pile shoe forms was considered under hammering pile sinking,and the pile body strain and soil plug changes were collected during the process of sinking pile.It is found that the resistance of pile sinking increases significantly after entering the hard sand layer,and the resistance at the end of the pile accounts for a relatively large proportion,and the pile shoe can effectively reduce the resistance of pile sinking.At the same soil position,the outer friction resistance will decay,and the inner unit friction resistance of the inverted 30°pile shoe pile is the largest.The pile end form had a significant influence on the soil plug,and the soil plug rates at the end of pile sinking were 41%,35%and 31%respectively.The pile shoe can effectively reduce the penetration resistance through the hard soil layer,and the research conclusion can be used to guide the construction of the pile driven,and provide references for the selection of suitable pile shoe form for the precast pipe pile driving process.