低标号素混凝土桩在杭金衢高速公路中的应用

由于杭金衢高速公路某段路基承载力要求较低，对混凝土的抗压强度要求不高，因此该路段加宽软基处理工程采用低标号素混凝土桩的地基处理方式．低标号素混凝土桩可按沉降控制要求设计，然后验算复合地基的承载力和稳定性．根据计算结果，确定低标号素混凝土桩的桩径、桩距及平面布置、桩长、桩体强度和配比，设计褥垫层，注意新老路基的连接．最后对低标号素混凝土桩进行低应变动力质量监测．结果表明，采用低标号素混凝土桩的地基处理方式，地基承载力大大高于设计要求，达到了减小工后沉降、加速施工工期的目的．

Application of low-grade plain concrete piles for a section of Hangjinqu Expressway

In consideration of the low sub-grade capacity and low compressive strength of concrete required by the section of the expressway, the low-grade plain concrete pile was adopted for widening of the soft foundation section. The piles were designed according to the requirement of settlement control. Based on the calculated results of the bearing capacity and stability of the composite foundation, the diameter, length, and strength of the piles as well as their arrangement and the concrete mixing ratio were determined, and the cushion layer was designed. In the treatment of the foundation, the connection of the new and old foundation was paid much attention. The low-strain dynamic quality monitoring of the concrete piles showed that the application of the piles made the bearing capacity of foundation much higher than the design value, decreased the post construction settlement, and shortened the construction period of the project, providing reference to foundation treatment in the similar projects.