EVALUASI PERGERAKAN TANGGUL LUMPUR SIDOARJO

The eruption of mudflow in Sidoarjo since 29th of May 2006 still continues and has resulted in the changing of soil condition in the surrounding area. Form handling of mudflow in this time is to build retaining embankment that surrounds the puddle area, where embankments rest on the thick and soft alluvium layer. This research aims to evaluate movement and stability analysis of embankment resulted the eruption of mudflow. Methods in this research is having study on the secondary and primery data to get input parameter in the calculation. At this simulation used by embankment P10D/KR5 of condition exsisting. The numerical simulation used Plaxis program on the plane strain condition with Mohr-Coulomb model for embankment and soil, while was gabion with its material approached by elastic linear model. The research results show that the embankment stability towards the collapse of bearing capacity is about SF = 2,5. After the mud eruption, there is change on the condition of soil resulting in the embankment settlement about 2,578 m based on the monitoring data real. The result of numerical simulation was observed from the settlement and it was accurate enough according to the field measurement. If earthquake load was added to model, it resulted in the increase of vertical displacement about 8.0% on the embankment. The numerical simulation is able to show that being deeper from the soil surface, the horizontal displacement of soil is very significant and there is movement towards the eruption. It is done by modeling of change in the soil layer condition, the closer to the source of mud eruption, the layer condition is getting softer. At the end of filling with condition of eruption, the embankment stability declines drastically into SF = 1,103 for static load and SF = 1,095 if there is an earthquake. The erosion area tends to cut the embankment body until soil foundation