Prediction of Deformation of Caisson Type Piles in Open cut Works and Countermeasures Employing Early Closure Method

In open cut works in landslide areas, caisson type piles suffer much more severe deformation than predicted. The site was studied based upon additional geological surveys. From ground measurement results and back analysis, measures were considered necessary to prevent loosening associated with excavation at an early stage. In this project, as part of open cut works, the early closure method that has been proven to be effective in controlling deformation in mountain tunnels was used. In order to replicate the 3D restraint effect of natural ground, an appropriate construction method was planned from 3D FEM analysis. As a result, not only the rebound of the excavated bottom was suppressed, but also displacement of the pile and increase in rebar stress could be restricted. We believe that this method proved to be an effective construction method and established a prediction study method, and that this construction method can be used as a reference for similar construction.