Model tests on bucket-soil interaction during installation of bucket foundation in silt sand

The installation of bucket foundation is a vital construction procedure. The existing relative studies have mainly focused on the methods for calculating the penetration resistance and required suction. However, the understanding of the soil-skirt interaction during the installation is not clear yet due to inadequate test data. Model tests on the installation of bucket foundation are carried out in silt sand. The inner and outer soil pressures on the skirt are measured under both jacking installation and suction installation conditions. The jacking test results show that the inner soil pressures on the skirt are much larger than the outer ones. The compaction extent of the inner sand grows with the increase of the penetration depth, which is contrary to that of the outer sand. The suction test results show that the inner soil pressures decrease dramatically when the suction is applied. The outer soil pressures, however, increase firstly and then fall down to stable values rapidly. The inner friction and tip resistance are greatly reduced due to the seepage effects. The test results also indicate that the existing critical suction is too conservative. Based on the test results, the existing prediction method for the required suction is modified and evaluated, and a more accurate method is obtained.