Geotechnical Engineer

This paper presents slope failure causes, mechanism and a selected solution of an embankment on clay shale in one of most vital highways in Indonesia, the Cipularang Toll Road. The toll road was constructed in 2004 to 2005 to support economic growth in Jakarta, Bandung and the surrounding area. The toll road had to pass hills and valleys on clay shale of the Miocene Djatiluhur Marl formation. The slope failure occurred in February 2006 at Km 97+500 and attracted national attention due to its national critical function. This paper also presents the subsurface condition, the clay shale degrading strength due to exposure, back calculated strength parameters of degrading shale, slope movement monitoring result, geotechnical analyses and a group of bored piles as the selected reinforcement method. Geotechnical analyses were performed by utilizing PLAXIS, finite element software. The elastic plastic constitutive model and the Mohr-Coulomb failure criteria were chosen to model soils. Field monitoring during the following several heavy rains and geotechnical analyses show that a group of bored piles with a diameter of one meter is effective to stabilize the slope