软硬交互成层土静压桩挤土效应研究

Research on Compaction Effect of Jacked Pile in Soft Hard Layered Soil

基于ABAQUS有限元软件实现了软硬交互层状土中静压桩的连续贯入,考虑了挤土所产生的位移场、应力场、超静孔隙水压力及消散等问题。结果表明:不同土层静压桩挤土效应表现差异较大。在填土层,距桩2 d处,土体水平位移约为桩半径的5%,距桩5.5 d处,该比值约为1%;在淤泥质土层,距桩6.2 d处,土体水平位移约为桩半径的5%,距桩20 d处,该比值约为1%。软土层土体径向位移大于硬土层,径向应力小于硬土层。位移场、应力场均在土层交界面处出现突变。静压桩沉桩过程中由于挤土作用在低渗透性的饱和土中会产生较高的超静孔隙水压力,由于土层性质的差异,全风化花岗岩层压桩结束15天后消散达99.5%,淤泥质土层消散65.2%。

Based on ABAQUS finite element software, the continuous penetration of jacked pile in soft hard interaction layered soil is realized. The displacement field, stress field, excess pore water pressure and dissipation caused by soil compaction are considered. The results show that the squeezing effect of jacked pile in different soil layers is quite different. In the filling layer, the horizontal displacement of soil is about 5% of the pile radius at 2 d away from the pile, and the ratio is about 1% at 5.5 d from the pile;in the muddy soil layer, the horizontal displacement of soil is about 5% of the pile radius at 6.2 d away from the pile, and the ratio is about 1% at 20 d from the pile. The radial displacement of soft soil is larger than that of hard soil, and the radial stress of soft soil is less than that of hard soil. The displacement field and stress field appear mutation at the interface of soil layer. In the process of jacked pile driving, high excess pore water pressure will be produced in saturated soil with low permeability due to soil compaction. Due to the difference of soil properties, 99.5% of the total weathered granite laminated pile dissipated 15 days after the end of the pile, and 65.2% of the muddy soil layer dissipated.