Quantifying rock slope stability with kinematic and limit equilibrium methods for KM29 of Karak Highway, Malaysia

Engineering geology focuses heavily on ensuring the stability of rock slopes, especially to ensure that cut slopes next to roads are safe and functional. Kinematic analysis is a commonly utilized technique to assess the stability of rock slopes in Malaysia. This method employs a stereographic plot to identify potential failure modes based on geological discontinuities; however, it does not quantify the forces that could influence these failures. This restriction is addressed by calculating the slope's safety factor using the Limit Equilibrium Method (LEM), which offers a more thorough evaluation. This study used kinematic analysis and LEM to evaluate the stability of a rock slope at KM29 near the Gombak toll on the Karak Highway in Malaysia. Key parameters, including geological discontinuities and mechanical properties, were analyzed through Schmidt hammer rebound surveys and shear strength tests. A Schmidt rebound hammer was used to assess the rock's hardness; slope sections Gl, G2, and G3 had average values of 61.60 MPa, 60.00 MPa, and 54.40 MPa, respectively. Equivalent rock strength values of 163.97 MPa, 150.65 MPa, and 113.98 MPa were obtained by correlating these values with the uniaxial compressive strength (UCS). The shear strength test indicated an average cohesion value of 20.56 kPa and a friction angle of 56.790, derived from four rock samples. Kinematic analysis, conducted using Rocscience Dips software, revealed that slope sections Gl, G2, and G3 were susceptible to wedge and planar failures. In contrast, the factor of safety (FOS) determined by LEM, simulated using Slope/W, confirmed that all slope sections are stable, with FOS values exceeding 1.5. The integration of kinematic analysis and LEM should be considered essential for evaluating rock slope stability and reinforcing the final decision-making process.