Tunnel and Underground SpaceISSN:1225-1275(Print) 2287-1748(Online)한국암반공학회

The subject of this study is a rock slope composed of coal bearing mudstone that unconformably covers the Cenozoic Tertiary basalt strata in Pohang. Discontinuities developed within the slope are stratification and nonconformity, cooling joint and shear joint. As for the type and size of rock-failure by section, circular failure is dominant in the upper coal bearing mudstone section, and toppling failure is dominant in the lower basalt section, and the failure size of rock body is about 0.02 m to 0.01 m³ on average. As a result of synthesizing face- mapping data, SMR, physical properties/mechanical tests of soil and rocks, stereonet projection analysis, geological cross-sectional view analysis and limit equilibrium analysis for each section, all of the representative sections were significantly less than the allowable safety factor, requiring a countermeasure method. After applying the slope relief method and the rock anchor method as well as the green soil surface treatment method + installation of rockfall prevention fence, the safety factors of slope exceeded the allowable safety factor. Creating a geological cross-section of a representative section perpendicular to the slope, face-mapping data, and a limit equilibrium analysis reviewed by using the geological cross-section as a representative cross-section will be a reasonable tool for three-dimensional analysis of the slope stability. In the case of rock slopes that have developed stratification and nonconformity and are loosed such as coal bearing mudstone, it is essential to prepare systematic geological cross-sections. For the representative cross section used in the limit equilibrium analysis, it is reasonable to set the geological cross section for each section as the basic cross section.