Observation of sand movement during bucket installation

Abstract

The occurrence of soil-plug heave during bucket installation is one of the major problems in successful installation of bucket foundation at a desired depth. It is usually caused by the upward seepage flow created by continuous pumping out of water from inside the bucket as well as due to shear failure of the soil along the skirt wall during skirt penetration. This soil-plug heave eventually hinders the bucket to be installed at a targeted depth and hence affects its performance. This paper, therefore, presents the result of a series of bucket installation tests using half-bucket foundation performed in a box equipped with a transparent window for directly observing the soil movement around the bucket during installation. Continuous images were captured simultaneously during the entire suction installation process and subsequently analysed by particle image velocimetry to quantify the soil movement. The results provide: (a) the trend of suction pressure with wall embedment; (b) soil-displacement pattern and (c) the effects of penetration rate (i.e. water-pumping rate) and wall thickness on the soil displacement. The results also provide comprehensive insights into the mechanism of soil disturbance, including soil-heave formation, during suction installation.