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Volume 13 | Issue 5 | Year 2026 | Article Id. IJCE-V13I5P112 | DOI : https://doi.org/10.14445/23488352/IJCE-V13I5P112

Weathering-Controlled Transition of Slope Failure Mechanisms and Applicability of Kinematic Models in Silurian Schists (Rif, Northern Morocco)

MEROUANI Houda, DEKAYIR Abdellilah, ROUAI Mohamed, EL BALGHITI Youssef

Received Revised Accepted Published
14 Jan 2026 20 Feb 2026 11 Mar 2026 29 May 2026

Citation :

MEROUANI Houda, DEKAYIR Abdellilah, ROUAI Mohamed, EL BALGHITI Youssef, "Weathering-Controlled Transition of Slope Failure Mechanisms and Applicability of Kinematic Models in Silurian Schists (Rif, Northern Morocco)," International Journal of Civil Engineering, vol. 13, no. 5, pp. 172-186, 2026. Crossref, https://doi.org/10.14445/23488352/IJCE-V13I5P112

Abstract

Paleozoic schist on the Mediterranean road in northern Morocco presents a transition in slope stability from discontinuity-controlled to soil-like behavior. This phenomenon is related to the complex mechanical behavior shown under the effects of weathering processes. The present study investigates this transition in the Silurian schist on a slope near Tamrabet (northern Morocco). After field observations, six weathering zones were identified to define the critical changes between partially interbedded rock and heavily degraded matrix material. The findings of the petrographic, mineralogical, and geotechnical characterization together describe the progressive effects of weathering shown in the increasing porosity, decreasing bulk density, loss of mineral crystallinity, and leaching of mobile elements, which result in a significant contraction of the rock fabric, accompanied by swelling in the soil-like material resulting from weathering. The stability behavior of the slope mirrored the effect of this degradation on mechanical behavior. Kinematics models were used as a verification tool and systematically compared with instabilities observed in the field, highlighting both their relevance and their limitations. This comparison makes it possible to differentiate between rocky areas where instability is governed by the geometry of discontinuities and can be assessed using kinematic approaches, and heavily weathered areas where the behavior of the low-cohesion matrix controls the failure mechanisms that cannot be considered by these models. Overall, the results reveal the existence of a mechanical limit within the schist weathering profile and provide a comprehensive approach for soft-rock stability assessment in the transition phase between rock and soil.

Keywords

Schist, Rock–soil transition, Slope stability, Weathering, Geomechanics.

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