The Rock Mass Rating (RMR), Geological Strength Index (GSI) and kinematic analysis are widely employed in geotechnical engineering practice. The RMR and GSI both are used for rock mass characterization while the kinematic analysis is applied to identify the mode of failure of slope based on rock discontinuities and slope face characteristics of rock.

An attempt has been made to analyze the RMR, GSI and Kinematic Analysis using in-situ data corresponding to Vindhyan sandstone. The data has been collected from outcrops at seven different locations in and around Markundi hill along SH-5, Chopan, Sonbhadra. The relationship between RMR and GSI for Vindhyan sandstone in the study area has been attempted using generalize equation proposed by Hoek (2013) while the kinematic analysis has been applied to decipher the weak zone of failure using RocScience Dips software.

The lowest RMR value estimated is 35 for location S-4 and the highest RMR value is 58 for location S-1. Other locations viz, S-2, S-3, S-5, S-6 and S-7 have the RMR value from 42 to 49 which infers that the Vindhyan sandstone existing at Markundi is characterized by both poor as well as fair rock mass.

The GSI value of the location S-1 is estimated as 34 (minimum) and 46 (maximum) of location S-4. GSI value of the same rock formation also corroborates that the rock mass belongs to poor as well as fair rock mass.

The wedge failure is inferred due to intersection of two sets of joints oriented in north-west and north-east direction. The line of intersections of these two discontinuities are observed in wedge shaped block. It is concluded that the locations under investigations have tendency of wedge failure.

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