Study of Mineralogy and Engineering Properties of Volcanic Rock at the Base of the Pamukkulu DAM Foundation, South Sulawesi, Indonesia

At the location of the Pamukkulu dam, it has engineering geological characteristics that are less supportive of the construction above it, especially for the foundation of the dam. By taking data directly in the field and by laboratory testing, information is needed regarding the characterization of mineralogy and the engineering properties of rocks. Mineralogical analysis was performed with petrography and X-Ray Diffraction (XRD) while the engineering properties of the rock were performed with Plate Bearing Tests (PBT), Standard Penetration Tests (SPT), and Rock Mass Rating (RMR). Based on mineralogical data, rocks have undergone weathering and converted the chemical-physical properties of minerals into porous, fine-grained minerals, forming mineral oxides as well as clay minerals. The carrying capacity of surface soils in the dam area based on the plate bearing test is relatively poor. As for subsurface rocks, the weight of the rock mass rating belongs to the class (II) Good to (III) Medium. Meanwhile, from the density value of hard soils, there are different depths from a depth of 1 meter to 6 meters. Weathering conditions of rocks affect the engineering value of soils and rocks where due to weathering minerals formed in the form of porous clay minerals, they are not well consolidated.