Model Test Research on the Compaction Effect of Jacked Pile in Layered Soil

During the penetration process of jacked pile installation, the soil around pile will move laterally and heave. The existing structures and facilities were often damaged due to the soil movement resulted from jacked pile installation. To reduce those accidents, it is important to study the law of the lateral soil movement and upward heave due to compaction. This paper describes results from a series of experiments that investigated the radial soil displacement due to jacked piles in layered soils. A number of jacked piles were installed in a test chamber filled with dry sand and rubber powders, which was used to simulated soft soil. Closed-ended piles with 40-mm diameters were used. The experiments were carried out to study how radial displacement and vertical displacement changed as the pile penetration depth varied. We determined how the displacement value changed at different soil interfaces during the pile pressing process. The results revealed the soil displacement behavior produced by different position and penetration depth of the pile. We found that a lag effect existed between the maximum displacement and the pressed pile depth. The experimental results allow for a better understanding of the inherent mechanism of compaction of the jacked pile during the penetration process. These results are important for estimating the influence of pile installation and guiding jacked pile design.