Recently, heavy rainfall at local area intends to increase slope failure. Flow of water by rainfall between fractured rocks in a colluvium can cause rock slide failure. In this paper, the case of slope reinforcement on fractured rock was studied. The safety factor was analyzed by numerical method on the colluvium rock surface. Ground investigation, physical laboratory test, rock triaxial compression test, and field monitoring were performed. In order to prevent sliding failure or global shear failure by earth pres-sure, field pullout test was proceeded with the compression permanent anchor. Rock slope stability and design anchor force satisfied the standard specification. It was analyzed by stress reduction factor of Midas GTS NX program. In case of numerical analysis with seepage-stress coupled analysis, the stability and axial force are more critical in heavy rainfall condition. Therefore, it needs that groundwater flow in the bedrock should be controlled to prevent collapse of rock.
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