干作业长螺旋钻成孔灌注桩具有振动小、噪声低、不扰民、钻进速度快、施工方便等优点,但主要缺点是桩端或多或少留有虚土,只适用于在地下水位以上的土层中成孔。近20多年来,国内外推出将通常长螺旋钻机只能进行干作业拓展到进行湿作业(即在地下水位以下成孔桩作业)的施工新技术,如欧洲的CFA Drilling long screw auger bored piles with vibration, low noise, non-nuisance, drilling speed, construction convenience, but the main drawback is more or less pile left virtual soil, only for the groundwater level Above the soil into the hole. In the past two decades or so, domestic and foreign markets have introduced new construction technologies that normally extend long-auger rigs only for dry work to wet work (ie, forming piles below groundwater level) such as CFA