洞桩法在北京地铁12号线苏州桥站的应用

北京地铁12号线苏州桥站为地下暗挖车站,采用洞桩法进行桩柱一体化施工。针对地铁暗挖车站在砂卵石地层中的洞内机械成桩,采用革新改进后的反循环钻机进行洞内机械成孔,施工中通过改变设备外形尺寸、钻头功率、优化动力头配置及钻头形式等措施来适应砂卵石地层的需要。通过对成孔后分节下放桩基钢筋笼及钢护筒,成孔后分节下放桩基钢筋笼及钢管柱2种施工工艺的对比,可明显看出第2种工艺的优越性。

Application of Hole Pile Method to Suzhouqiao Station on Beijing Metro Line 12

Suzhouqiao Station on Beijing metro Line 12 is an underground excavation station,which adopts the hole pile method to implement the integrated construction of pile and column.To solve the problems of mechanical pile forming during underground excavation in sand and gravel stratum,an improved reverse circulation drilling machine is used to make mechanical holes.Through changing the overall equipment dimension and drilling bit power,optimizing the distribution of power head and bit form,the needs of the sandy pebble stratum are covered.Two construction methods—the steel cage and steel cage of pile foundation distributed after drilling,the steel cage and steel tube of pile foundation divided into sections after drilling—are compared,the advantages of the second one is obvious.