Slope Stability of Cengklik Earthfill Dam, Boyolali Regency, Central Java']Java Province, Indonesia

Cengklik earthfill dam, Boyolali district, Central Java province encounters cracks and seepages on the body of the dam. Those problems are affect on the stability of the dam slope. This study aims to determine the stability of embankment of the dam and its mitigation. The method used in this research is geotechical mapping, core drilling and soil sampling either disturbed and undisturbed for soil mechanical laboratory tests. The tests are conducted to obtain the parameter value of engineering properties of dam materials. The parameter values are used to calculate and simulate the slope safety level with the Slide 6.0 on ten different dam conditions. Based on the calculation results, it was found that there are two stability conditions of the dam body slope that do not satisfying the Indonesian National Standard (SNI) of dam safety factor resulted in vulnerable to sliding. The dam body conditions are the maximum water level condition on downstream slopes without earthquake loading and maximum water level condition on the downstream slope with earthquake loading. Mitigation has been proposed to overcome the problems.