Characteristics of Engineering Geology in Talegong Road, Talegong, Garut, West Java, Indonesia

Abstract

Talegong road, Garut, West Java, is provincial road with a length of 7 kilometers that connects Garut and Bandung. The road segment KM 2.3 – KM 7 is located between the steep slope of high hills and has potential for landslide. To find out the landslide potential, determining the characteristics of geology and engineering geology at this road segment are needed. The methods used in this research are engineering geology mapping (geomorphology, lithology, structural geology and rock mass quality) and laboratory analyses of soil and rock properties index, shear strength test, petrographic analysis and uniaxial compressive strength test. The results of geological mapping show the aspect geomorphological in the area consists of high hills with rather steep to very steep slopes. Lithological, the area consists of aphanitic andesite and porphyritic andesite. The area is dominated by Northeast – Southeast stress regime. In term of rock mass quality, the study area consists of three class with value in Rock Mass Rating classification, which are good rock, fair rock, poor rock and no value rock (soil). The study area is divided into three units in the engineering geological map: (1) unit A has fair – good rock (II – III) with rather steep - very steep slope with low landslide potential, (2) unit B has fair rock (III) with steep – very steep slope with medium landslide potential, and (3) unit C has poor – no value rock or soil (IV – 0) with a very steep slope with high landslide potential.