端帽式碎石注浆桩在路堤荷载下工作性状

Research on Performances of Grouting Crushed-Stone Column with End Caps under the Load of Embankment

为有效控制路基的工后沉降,提出了路堤荷载下端帽式碎石注浆桩技术。针对路堤荷载下复合地基的工作性状,对端帽式碎石注浆桩进行了分析,研究表明:上端帽提高了桩体荷载分担比,减小了桩顶刺入变形;通过桩体穿越软土层将更多路堤载荷传至深层,减小软土层后期沉降;提高注浆压力以扩大注浆加固区半径,加强浅层注浆,减小桩间土沉降。桩下端注浆扩大体,对所在持力层进行挤密加固;扩大桩底面积,减少桩体向下的刺入变形,降低复合地基工后沉降。对不同桩距、浆液扩散区进行比较,提出了合理的布桩建议。与普通碎石注浆桩相比,端帽式碎石注浆桩在提高承载力和减少复合地基沉降,特别在控制路基的工后沉降方面效果显著。

A technique about the crushed-stone grouting column with end caps under the load of embankment is proposed in this paper.It can reduce the post-construction settlement of subgrade effectively.Based on the characteristics of composite foundation under the load of embankment,the ordinary grouting crushed-stone columns and the grouting crushed-stone columns with end caps are compared.It is shown that the top end cap of this column can improve the load sharing ratio of column,decrease the upward penetration of pile top;with more embankment loads are transferred from soft soil to the deep soil layer by columns,the post-construction settlement of soft soil will decrease.By improve grouting pressure to expand the grouting reinforcement area radius and strengthen the shallow grouting,the settlement can be greatly reduced.The expanded body of the grouting at the column＇s bottom can also compact and reinforce the bearing stratum,enlarge the column bottom area,and decrease the downward penetrating deformation of the column,which leads to the reduction of the post-construction settlement of composite foundation.Based on the comparison of different column spacing and spreading area of grouting,a reasonable suggestion about column arrangement is proposed.Compared to the ordinary grouting crushed-stone column,grouting crushed-stone column with end caps performs much better in enhancing bearing capacity and reducing settlement of composite foundation,especially in controlling the post-construction settlement of the subgade.