Abstract
This paper reports a case study of applying wet and top feed vibro replacement stone columns to support the 20-m-high fuel tank built on loose to medium sand deposits. The design considerations, installations, applications, field tests, correlations, and subsequent three-dimensional finite element analyses are presented. The soil profile of the case study comprised approximately 8 to 12 m thick loose to medium-dense silty sand layers with a high groundwater table. The 1-m-diameter stone columns were installed in a triangular pattern with a spacing of 2.1 m. The improvement depths were 8, 11, and 12 m. After construction was completed, quality assurance of the stone column installation by various field tests was performed. Based on the hydro test results, the improved ground could carry an allowable bearing capacity of 200 kPa transferred from the 20-m-high fuel tank and exhibited a maximum settlement of smaller than 50 mm, which met the design criteria of this project. Due to reasonable quality control during stone column installation, the tank’s tilt caused by the non-uniformity of the improved sands was negligible because it was lower than 10 mm. The enhanced strength ratio of the surrounding sands was 2 to 3 due to the desification effect. The simulated data confirmed the observed results, and the verification or confirmatory test results illustrated the successful applications of the vibro-replacement stone columns.