在水源井成井的施工过程中,由于地质条件复杂和工程本身的需要,往往要下入数套不同直径的大径套管,为了在套管内下入较大直径的深井泵,有的套管上端既不能延伸到地表,又因地层条件复杂,不可能直接焊于大一级套管下端,使两级套管一次下入 Due to the complex geological conditions and the needs of the project itself, a large number of sets of large-diameter casing with different diameters often need to be put into operation in the process of forming a well of a water source shaft. In order to enter a deep-well pump of larger diameter in the casing, The upper can neither extend to the surface, but also because of complex formation conditions, can not be directly welded to the lower end of the casing, the two casing once