ANALYSIS OF THE EFFECT OF MOISTURE CONTENT AND SWELL PRESSURE ON THE SHEAR STRENGTH OF BOBONARO CLAY IN THE KUPANG REGION, EAST NUSA TENGGARA PROVINCE

The Bobonaro Formation, which is widely distributed in the Kupang region, East Nusa Tenggara Province, is known to have a dominant expansive clay lithology. This formation forms the basis for several very important infrastructure projects, including the Manikin Dam, where expansive clay soil can pose challenges to stability and deformation control. This study aims to analyze the relationship between moisture content, swell pressure, and shear strength in Bobonaro Clay taken from several locations in Kupang Regency and Kupang City, which have the same geological formation as the Manikin Dam area. Laboratory tests included natural moisture content, Atterberg limits, specific gravity, standard proctor compaction, direct shear test, and swell pressure test. Linear regression analysis was used to determine the relationship between parameters. The results of this study indicate that an increase in moisture content causes a decrease in shear strength and an increase in swelling pressure simultaneously. These findings confirm the expansive nature of Bobonaro Clay and provide important geotechnical insights for the planning and implementation of construction in areas with this formation.