Under the condition of tamping energy 975－1 125 kN•m per blow with four kinds of typic tampers including the shock absorbed and assembled tamper (SAAT) designed by the first author

the tests of vibration acceleration and comparative tamping settlement are carried out in-situ during the improvement of mud ground with high water content and great void ratio by using the static-dynamic drainage consolidation (SDDC); SAAT first contact with ground

rebound

and impact secondary action lasted for 15ms

80 ms and 35 ms respectively; vertical and horizontal acceleration under the four temper action descend sharp within 10 m and 5m respectively; the synthesized safety distances satisfying the requirement of relevant code (under seismic intensity grade Ⅶ）are obtained as 20－30 m under the condition

and the safety distance for SAAT is least; the result shows that the SAAT enhances the effect of MSDDC in evidence and diminishes vibration influence on surrounding environment obviously. Besides

transmissions of vibration acceleration produced by impacting are analyzed.