全套管全回转在含抛石淤泥地层加固工程中的应用

在对含有抛石淤泥地层既有建筑加固桩基施工时,常规采用泥浆护壁回转成孔、旋挖成孔、冲击成孔的施工方法受到限制,尤其是成孔产生的振动对敏感建筑物造成的影响不容忽视,为尽量减少对既有建筑和土层的扰动,需采用干扰小,且能够保证既有建筑建筑安全的工艺。由于全套管全回转钻机工法技术灵活多样、机械化程度高,具有施工安全、可靠、对周围扰动较小、成孔垂直精度高、无泥浆污染等特点,此工艺在邻近既有建筑桩基施工中得到较多应用。通过介绍全套管全回转工艺在大连某项目加固中的应用,针对该工艺成孔具有不塌孔、无泥浆等特点,为提高桩基承载力和桩身质量,采用气举反循环和泵举反循环等工艺清孔,达到严格沉渣控制要求,为此后类似嵌岩桩基施工提供参考和经验。

Application of Full Casing Full Rotation in Reinforcement Engineering of a Riprap Silt Stratum

In the construction of existing building reinforcement piles in riprap silt strata,the conventional construction methods of rotary drilling,spiral digging and impact holing with slurry supporting are limited.The impact of vibrations on sensitive buildings generated by drilling cannot be ignored.In order to minimize the disturbance to existing buildings and soil layers,it is necessary to adopt a process with little interference to ensure the safety of existing buildings.Due to the flexible technology and high degree of mechanization of the full casing full rotation,combining with advantages of safe,reliability,small disturbance to the surrounding,high vertical precision of the hole and no mud pollution,this technology has been widely used in the pile foundation construction of adjacent existing buildings.The application of the full casing full rotation in the reinforcement of a project in Dalian is introduced.Focusing on the characteristics of no hole collapse and no mud during drilling,in order to improve the bearing capacity of the pile foundation and the quality of the pile body,gas lift reverse circulation and pump lift reverse cycle are applied,achieving strict sediment control requirements.It provides reference and experience for similar construction of rock-socketed pile foundation.