Development on the Micropile for Applying to Artificial Ground above Railroad Site

Abstract

The Korean government recently launched a new policy supplying rental housing at reasonable prices by building a complex on the artificial ground above railroad sites. One of the crucial factors to make the artificial ground is the selection of foundation type which can satisfy the given site conditions, such as bearing capacity, construction speed and cost efficiency at the same time. The most representative method to achieve a bearing capacity and construction time is using a micropile. This can be constructed in the narrow space between the railway lines. However, utilization of the micropile entails high cost on overall construction due to the high price of micropile. This is due to, rather than cast-in-place concrete pile or PHC pile which are commonly used for the foundation type on construction sites in Korea. The purpose of this study is to find improvements of the cost efficiency and to find the bearing capacity with the micropile, The Jet Grouting method has been implemented to increase soil strength by making waveform which has a regular bell shape curve to the grout body for reducing the micropile length due to the increase of bearing capacity. The numerical analysis results showed the new micropile achieves higher performance at bearing capacity compared with the existing micropile. Additionally, the factors which should be considered during evaluating the bearing capacity of the new micropile were suggested according to the location and space between the waveform of the grout body.