Warta Geologi, Vol. 51, No. 3, December 2025, pp. 184-192
Nur Anati Binti Azmi*, Zainuddin Bin Md Yusoff
Civil Engineering Department, Faculty of Engineering, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
*Corresponding author email address: anati.azmi@gmail.com
Abstract: Slope failure is a significant geotechnical issue observed in various regions worldwide, posing a threat to critical infrastructure, such as the Lebuh Raya Pantai Timur 1 (LPT1) highway in Malaysia, which is founded on the Semantan Formation, while the westernmost outcrop near Lanchang (km 90) consists of acidic igneous rocks. The objective of this study is to assess the stability of the rock slopes of the LPT1 highway corridor, identify the factors contributing to slope instability and recommend appropriate mitigation measures. The study involves both qualitative data, obtained through field observations and quantitative data through experimental methods, and numerical modeling techniques, including kinematic analysis and the limit equilibrium method. In the kinematic analysis, possible failure modes such as plane, wedge, and toppling failures were identified. The Limit Equilibrium Method (LEM) was employed to calculate the factor of safety (FoS) under standard conditions. The results suggest that overall the slope is generally stable; however, localized instabilities may occur due to wedge failure mechanisms. The calculated FoS values range from 0.4 to 2.2, indicating a stability range from low to high. By focusing on failure mechanisms, the impact of discontinuities, and the role of shear strength and water content, this study offers valuable insights. The findings contribute to the development of reliable remedial measures to mitigate slope failure risks and enhance the stability of other crucial infrastructures. In response to potential risks, the concessionaire of the highway has already taken proactive steps to implement stabilization measures, reinforcing the slopes to ensure their safety and mitigate failure risks moving forward.
Keywords: Slope stability, rock slope failure, Semantan Formation, LPT1 highway, kinematical analysis, Limit Equilibrium Analysis, factor of safety
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Manuscript received 29 November 2024;
Received in revised form 23 January 2025;
Accepted 15 July 2025
Available online 30 December 2025
DOI: https://doi.org/10.7186/wg513202503512202503
0126-5539; 2682-7549 / Published by the Geological Society of Malaysia.
© 2025 by the Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC-BY) License 4.0
