Abstract: The disturbance effect on a very deep soft clay foundation due to steel tube driving was studied by use of in-situ tests.It was shown that the extruding displacement(i.e.,ground surface settlement,ground surface displacement,and horizontal displacement of soil layer) caused by driving and drawing of a steel tube was not great.Extruding stress and pore pressure generated by driving and drawing of the tube in a local region surrounding the pile increased obviously with the increase of the driving depth of the steel tube;however,the extruding effect was mainly limited within a radial distance of about 1.5 m.In the meantime,the location of the maximum horizontal displacement of soil layer was also moving downward.Moreover,the maximum values of horizontal displacement were smaller than 5 mm when the radial distance was greater than 1.5 m.