Landslides, fault movements as well as shrink/swell soil displacements can exert important additional loadings on soil buried structures such as pipelines. These loadings may damage the buried structures whenever they reach the strength limits of the structure material. This paper presents a two-dimensional plane-strain finite element analysis of an 800 mm diameter water supply pipeline buried within the expansive clay of the Ain-Tine area (Mila, Algeria), considering the unsaturated behavior of the soil under a rainfall infiltration of 4 mm/day intensity and which lasts for different time durations (8, 15 and 30 days). The simulations were carried out using the commercial software module SIGMA/W and considering different initial soil suction conditions P1, P2, P3 and P4. The soil surface heave and the radial induced forces on the pipeline ring (i.e., Axial , Shear  forces and bending moments ) results indicated that following the changes of suction the rainfall infiltration can cause considerable additional loads on the buried pipeline. Moreover, these loads are proportionally related to the initial soil suction conditions as well as to the rainfall infiltration time duration. The study highlighted that the unsaturated behavior of expansive soils because of their volume instability are very sensitive to climatic conditions and can exert adverse effects on pipelines buried within such soils. As a result, consistent pipeline design should seriously consider the study of the effect of the climatic conditions on the overall stability of the pipeline structure.

Permanent ground deformations (PGDs) induced by slope failures cause catastrophic damage to buried pipelines. This paper presents a 2D plane-strain numerical analysis of the behavior of a 800 mm water transport pipeline buried in the Aine-Tine slope (Mila, Algeria) subjected to shallow PGD, as it could be triggered by the recent earthquake of August 07th, 2020 (M= 4.9). The analysis is carried out through the application of an incremental displacement to simulate the soil-pipeline interaction while focusing on the effect of (1) the magnitude of the PGD and (2) the rigidity of the pipeline on the structural response of the pipeline. The elasticperfectly Mohr-Coulomb model was used to simulate the soil behavior and the elastic model was used to simulate that of the steel pipe. Pipeline deformations (i.e., translation and ovalization) and radial internal forces’ (i.e., axial forces F୅, shear forces Fୗ and bending moments M୆) results highlighted that shallow PGD can exert additional loads on pipelines that are proportional to the magnitude of the PGD. It has been found that the soil deformations as well as the internal forces induced on the pipeline ring are higher for rigid pipelines. Moreover, the results indicated that rigid pipelines are more effective than flexible ones as far as ovalization-serviceability limit state is concerned. In effect, for PGD magnitudes of 0.5, 1 and 2 m, the ovalization values of the flexible pipeline are, respectively, higher by 23%, 21% and 18% than those calculated for the rigid pipeline. Through a simplified linear numerical simulation such as that presented in this study, engineers and planners could be guided to foresee the possible causes of pipeline leaks and the mechanisms of ruptures that lead very often to severe disruption of pipelines’ normal operation. KEYWORDS: Soil-structure interaction, Slope failure, Permanent ground deformation, Pipelines, Radial internal forces, Ovalization

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