- Abstract
In the self-balanced pile test in the deep excavation, effective measures are taken to eliminate the side friction effect after excavation. The unloading of deep overburden excavation caused decrease in soil confining pressure surrounding engineering pile and as a result reduce of the upper load box pile pullout capacity. Based on the additional correlation analysis method, the negative friction, base and relevant soil mechanics theory, a simplified analysis method of Mindlin and negative friction-additional stress solutions are proposed. The column pile in a subway station in Beijing is studied to estimate the loss of upper pile bearing capacity caused by deep excavation soil unloading. The results of the two methods show significant difference and the reasons are discussed. The applicability and accuracy of the two simplified analysis methods require further study..