超厚砂卵石地层气举反循环钻探工艺

Air-lift reverse technique in super thick sandy gravel

采用气举反循环的钻探工艺,在孔径为3.0 m、厚度为33 m的超厚砂卵石地层桩基础施工中,改进了钻进施工工艺方法。研究结果表明:采用改进后的泥浆循环系统,提高了排渣的效率,实现了边正常钻进边排渣的工作流程,在实际工程应用中具有可操作性;通过研究孔壁稳定与泥浆指标、孔内水头位置进行工程试验,获得的泥浆粘度比常规值低,节约了造浆成本,提高了钻探效益。此外,提出一个新的钻杆孔内有效气量的简化计算公式。

Adopting air-lift reverse technique in super thick sandy gravels with thickness of 33 m and 3.0 m in pile diameter, construction technique and its drilling method were improved. It was more manipulative and more efficient in getting ride of drilling sediment in sediment-box during operation by improved general slurry-cycle system. Based on some drilling experiments for slurry parameters and stabilization of drilling-cliff, a new parameter of viscosity was acquired that is lower than required standard value and is proved to be applicable, a large amount of slurry expenses is saved, and the drilling efficiency is increased greatly. A simplified formula of effective gas quantity in drilling pole was presented.