潜孔冲击水泥土复合预制桩在复杂地层地基处理中的应用研究

Application of Down-the-hole Impact Cement Soil Composite Precast Pile in Foundation Treatment of Complex Stratum

针对浙江省一大桥及接线工程在复杂地层的傍山路段使用预应力管桩出现边坡滑移、路面裂缝等问题,采用潜孔冲击水泥土复合预制桩对该路段进行加固处理,采用有限元软件建立路堤边坡滑动模型对比加固前后的路基变形和稳定性。结果表明:采用潜孔冲击水泥土复合预制桩加固后能有效约束周围土体变形,分担上部路堤荷载,提高路堤边坡稳定性;在复杂地层地区,潜孔冲击高压旋喷工艺不仅能解决施工难的问题,并且成桩质量高,加固效果好;对于不均匀软土分布,桩基应打穿软土层,减小路堤的填高,提高上部结构整体的安全性。

In view of the problems of slope sliding and pavement cracks caused by the use of prestressed pipe piles in the mountain side section of a bridge and connection project in Zhejiang Province,the section was reinforced with downthe-hole impact cement soil composite precast piles,and the embankment slope sliding model was established by PLAXIS software to compare the subgrade deformation and stability before and after reinforcement. The results show that the reinforcement of down-the-hole impact cement soil composite precast pile can effectively restrain the deformation of surrounding soil,share the load of upper embankment and improve the stability of embankment slope. In complex stratum area,down-the-hole impact high-pressure jet grouting technology can not only solve the problem of difficult construction,but also have high pile quality and good reinforcement effect. For uneven distribution of soft soil,the pile foundation should be penetrated through the soft soil to reduce embankment filling height and improve the overall safety of the superstructure.