Calculation Model of Compaction Coefficient of Soil among SP−PSC Pile Group on Collapsible Loess Foundation

Abstract

Collapsible loess is a kind of soil with special properties, and is widely distributed in China. When it is not wetted by water, its strength is generally high and its compressibility is low. However, when collapsible loess is wetted by water under a certain pressure, the soil structure will be rapidly destroyed, resulting in large additional subsidence. Therefore, when engineering constructions on collapsible loess sites are carried out, appropriate foundation treatment measures must be taken to eliminate foundation collapsibility. Because of their advantages, static pressure plain soil compaction (SP−PSC) piles are widely used for collapsible loess foundation treatments in China. However, at present, there is still a lack of accurate understanding of the distribution of compaction coefficient of soil among SP−PSC pile groups on collapsible loess foundations. The present study systematically investigated the distribution of the soil compaction coefficient among SP−PSC pile groups based on SP−PSC pile group tests and finite element analyses. The effect of different factors on soil compaction coefficient was analyzed and explored, including the pile diameter and length of SP−PSC piles, the soil moisture content, the pile spacing within the SP−PSC pile group, and the depth to ground. Finally, the simplified calculation models of the compaction coefficient of the soil at the center of pile group and at the midpoints of adjacent piles were analytically formulated. These models established a theoretical basis for the design and construction of SP−PSC pile groups on collapsible loess foundations.