FIELD TEST OF SOFT SOIL IMPROVED BY A COMBINED METHOD WITH VACUUM AND SURCHARGE PRELOADING

The combined method with vacuum and surcharge preloading is an effective alternative to improve the thick soft soil. This paper introduced a field test of soft soil improved by the combined method with vacuum and surcharge preloading. The vacuum pressure under membrane, settlement of ground surface and pore water pressure in soil were monitored during the preloading period. The final settlement was predicted based on the field data. The average degrees of consolidation in terms of stress and strain were calculated respectively. The test results indicated that the differential settlement was mainly developed during the surcharge preloading period. The vacuum pressure decreased down the drain length. The computed average degrees of consolidation in terms of stress and strain were 90.2% and 91.8%, respectively, indicating that the most settlement occurred during the preloading period and a satisfactory improvement effect was achieved.