Abstract: The soil improvement by blasting method has the advantages of simple construction process, short construction period and cost effective. The vertical settlement of soft soils improved by this method is one of the indicators for the treatment effect. This method is widely applied in strengthening soft soils in the coastal tidal zone. However, the vertical deformation pattern of improved soils is rarely reported. To investigate the settlement of the improved soils in the tidal zone, a long-term settlement observation program for highway project by using the settlement plates was implemented. The results indicate that the settlement of the roadway embankment stabilized after 50 days after the blasting treatment. The observed maximum settlement value in 172 days was 0.307 m and the settlement plate No. 1 was stabilized in during observation period.

Key words: soil improvement by blasting method, tidal zone, coastal soft soils, settlement plate, vertical settlement