联合后注浆对群桩基础工程特性的影响

Research on Influence of Combined Post-grouting on the Engineering Characteristics of Group Pile Foundation

为研究桩端桩侧联合后注浆对灌注桩群桩基础工程特性的影响,基于中山西环高速公路工程,利用有限元软件Midas GTS计算了3×3群桩在未注浆状态和桩端桩侧联合后注浆状态下的竖向沉降,以此为基础对比分析了注浆前、后群桩角桩、边桩及中心桩的桩身轴力和桩侧摩阻力变化情况,并通过工程实例验证了该后注浆方法的优越性。结果表明,桩端桩侧联合后注浆在控制桩体沉降、减小桩身轴力、增大桩侧摩阻力方面具有较好的处理效果;采用桩端桩侧联合后注浆的群桩的桩身轴力随着土层深度的增加先增大后减小,注浆后桩身轴力值减小至未注浆状态时的1/10左右;同时,桩端桩侧联合后注浆有效地减小了桩侧负摩阻力的不利影响,显著地提高了群桩基础的承载能力。

In order to study the influence of pile-end-pile-side combined post-grouting on the engineering characteristics of cast-in-place pile groups,based on the Zhongshan West Ring Expressway project,the finite element software Midas GTS is used to calculate the vertical settlement of 3×3pile groups.The calculation types include non-grouting and post-grouting after the pile end and pile side are combined.On this basis,the changes in the pile shaft axial force and pile side friction of the corner,side,and center piles before and after grouting are compared and analyzed,and the superiority of the grouting method is verified through engineering practice.The results show that the post-grouting after the pile-end and pile-side combination has a better treatment effect in controlling the settlement of the pile,reducing the axial force of the pile,and increasing the friction resistance of the pile.The axial force of pile groups with pile-end and pile-side grouting after grouting increases firstly and then decreases with the increase of soil depth.After grouting,the axial force value of piles is reduced by nearly 10 times compared with the ungrouted state.At the same time,the post-grouting after the pile-end and pile-side combination effectively reduces the negative impact of the negative friction of the pile side and significantly improves the bearing capacity of the pile group foundation.