Analysis on the lateral earth pressure coefficients of soil plugs for large diameter driven piles considering plugging effect

When the installation of large diameter driven pile, the plugging effect is generally caused as the partially plugged condition. In this condition, it is a key issue for design because the inner shaft friction between soil plugs caused by plugging effect and pile's inside surface causes additional bearing capacity of driven piles. Thus, this study suggested a new method for evaluating the inner shaft friction caused by partially plugged condition. The CEL (Coupled- Eulerian-Lagrangian) method was used to simulate the driven pile installation process and proposed the trend of lateral earth pressure coefficient (Kplug) in soil plugs and the normalized effective soil plug's height. In order to consider drieveability during the hammer driving, each driving energy was separately calculated in each analysis case. Based on parameter studies, it was shown that the plugging effect decreased with increasing the pile diameter, and increased with increasing the pile length, the elastic modulus of soil and the driving energy. It was found that the trend of Kplug had almost uniform trends under the different parameters. A simple equation for inner shaft friction at the pile inside was proposed by using the proposed Kplug.