Publications by Author: Demagh, Rafik

2023
Bouatia M, Demagh R, Derriche Z. numerical investigation of buried pipelines subjected to permanent ground deformation due to shallow slope failure (part i: transverse behaviour). Jordan Journal of Civil Engineering, JJCE [Internet]. 2023;17 (1). Publisher's VersionAbstract
Permanent Ground Deformations (PGD) that follow slope failures caused catastrophic damages on buried pipelines. This paper presents a two-dimensional numerical analysis of the behavior of an 800mm water transport pipeline buried in the Aine-Tine slope (Mila, Algeria) subjected to shallow PGD triggered by the recent earthquake of August 07th, 2020 (M= 4.9). The soil-pipeline interaction was simulated focusing on the effect of (1) the magnitudes of the PGD and (2) the rigidity of the pipeline on the structural response of the pipeline. The pipeline deformations (i.e., translation and ovalization) and radial internal efforts (i.e., axial forces F_A, shear forces F_S, and bending moments M_B) result highlighted that shallow PGD can cause additional loads on pipelines that are proportional to the magnitude of PGD. Moreover, it was found that rigid pipelines are more performant than flexible pipelines. Through a simplified numerical simulation, the study helps engineers and planners to predict the actual causes of pipeline leaks and ruptures leading to severe disruption of their normal operations.
2022
Amrane M, Messast S, Demagh R. Analyse Numerique D’une Fondation Superficielle Reposant Sur Un Sol Non-Sature En Hypoplasticite. 5ème Colloque International sur les sols Non Saturés, UNSAT, 15-16 Mars. 2022.
Djenane M, Demagh R, Hammoud F. Rotation of Stresses in French Wheel Tracking Test. Civil Engineering Journal [Internet]. 2022;8 (3). Publisher's VersionAbstract
The main function of a pavement is to distribute the traffic-induced load over its different layers. While the flexible pavement design methods are based on a linear elastic calculation, the real behavior of the different layers is highly nonlinear and elastic. They can also, in some cases, be plastic and viscous. This research aims to develop a three-dimensional numerical model that is closely similar to the test FWTT conditions. The model will have a real geometry wheel footprint (rather than a rectangular shape). As a substitute for incremental loading, the wheel movement during its passage over the specimen will be simulated by a horizontal displacement. These important characteristics of the model represent the novelty and the major difference between the current research and previous studies. The current model, which is based on the finite elements method, uses Abaqus software and a viscoelastic constitutive model. The materials’ viscoelastic properties have been described by the Prony series, also called the relaxation modulus, which is a function of time. This parameter can be defined in most computer-aided engineering (CAE) software. The procedure for calculating the Prony series from experimental data is explained. The results obtained agree with the stress signal amplitude, the stress rotation principal, and the total displacement rotation when the load approaches the node considered and located in the middle of the specimen.
2021
Zerdia M, Demagh R. Analyse Numérique tridimensionnelle de l’interaction de Tunnels Jumeaux- étude de cas. The 2nd International Symposium on Construction Management and Civil Engineering (ISCMCE- 2021), 10-11 Novembre [Internet]. 2021. Publisher's Version
Amrane M, Messast S, Demagh R. Évaluation de la capacité portante des sols stratifiés à l'aide d'un logiciel d'analyse par éléments finis. The 2nd International Symposium on Construction Management and Civil Engineering (ISCMCE- 2021),10-11 Novembre. 2021.
Bezih K, Demagh R, Djenane M, Laouche M. Impact of long-term soil deformations on the performance of RC bridges considering soil-structure interaction. First International Conference on Geotechnical, Structural and Advanced Materials Engineering (ICGSAME’ 2021), 05-07 Décembre. 2021.
Amrane M, Messast S, Demagh R. La Reponse D’une Fondation Superficielle A Une Infiltration Continue A La Surface Du Sol. The 2nd International Symposium on Construction Management and Civil Engineering (ISCMCE- 2021), 10-11 Novembre,. 2021.
2020
Bezih K, Chateauneuf A, Demagh R. Effect of Long-Term Soil Deformations on RC Structures Including Soil-Structure Interaction. Civil Engineering Journal [Internet]. 2020;6 (12). Publisher's VersionAbstract
Lifetime service of Reinforced Concrete (RC) structures is of major interest. It depends on the action of the superstructure and the response of soil contact at the same time. Therefore, it is necessary to consider the soil-structure interaction in the safety analysis of the RC structures to ensure reliable and economical design. In this paper, a finite element model of soil-structure interaction is developed. This model addresses the effect of long-term soil deformations on the structural safety of RC structures. It is also applied to real RC structures where soil-structure interaction is considered in the function of time. The modeling of the mechanical analysis of the soil-structure system is implemented as a one-dimensional model of a spring element to simulate a real case of RC continuous beams. The finite element method is used in this model to address the nonlinear time behavior of the soil and to calculate the consolidation settlement at the support-sections and the bending moment of RC structures girders. Numerical simulation tests with different loading services were performed on three types of soft soils with several compressibility parameters. This is done for homogeneous and heterogeneous soils. The finite element model of soil-structure interaction provides a practical approach to show and to quantify; (1) the importance of the variability of the compressibility parameters, and (2) the heterogeneity soil behavior in the safety RC structures assessment. It also shows a significant impact of soil-structure interaction, especially with nonlinear soil behavior versus the time on the design rules of redundant RC structures.
Amrane M, Messast S, Demagh R. Improvement of a Hypoplastic Model for Granular Materials under High Confining Pressures. Geotechnical and Geological Engineering [Internet]. 2020;38 :3761–3771. Publisher's VersionAbstract
The behavior of granular materials during loading depends on the level of stresses. When confining pressure increases, the peak shear strength, the residual shear strength and the stiffness gradually decrease; besides, the volumetric behavior is shown to be influenced by the stress level. In this paper, such effects, due to changes in stress levels, have been incorporated into a modified von Wolffersdorff hypoplastic model. For this purpose, reference void ratios and exponent α and β, the parameters of the original hypoplastic model are modified using experimental data. The performance of the proposed model is demonstrated by using simulated triaxial tests on Hostun sand with cell pressures up to 15 MPa. The study shows the ability of the improved model to highlight the behavior characteristics of granular materials in dilatancy and (peak) resistance under high stress better than the original model.
Zerdia M, Demagh R. Numerical Investigation of Shallow Twin Tunnels Interaction in Soft GroundNumerical Investigation of Shallow Twin Tunnels Interaction in Soft Ground. ITA-AITES World Tunnel Congress, WTC2020 and 46th General Assembly Convention Centre, 11-17 September,. 2020.
Bouatia M, Demagh R, Derriche Z. Structural Behavior of Pipelines Buried in Expansive Soils under Rainfall Infiltration (Part I: Transverse Behavior). Civil Engineering Journal [Internet]. 2020. Publisher's VersionAbstract
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.
Bezih K, Chateauneuf A, Demagh R. Effect of Long-Term Soil Deformations on RC Structures Including Soil-Structure Interaction. Civil Engineering JournalCivil Engineering Journal. 2020;6 :2290-2311.
Bouatia M, Demagh R, Derriche Z. Structural behavior of pipelines buried in expansive soils under rainfall infiltration (Part I: transverse behavior). Civil Engineering JournalCivil Engineering Journal. 2020;6 :1822-1838.
2019
Bezih K, Demagh R, Amrane M. Analyse mécano-fiabiliste des structures en béton armé en tenant compte de l'interaction sol-structure. First International Congress on Advanced Geotechnical Engineering and Construction Management (ICAGECM’19), 9-10 December. 2019.
Zerdia M, Demagh R. Analyse Numérique 3D de l’Interaction de Tunnels Jumeaux Investigation des Cuvettes Transversales. First International Congress on Advanced Geotechnical Engineering and Construction Management (ICAGECM’19), 9-10 December [Internet]. 2019. Publisher's Version
Beghoul M, Demagh R. Analysis of Ground Surface Settlement Induced By Shield Tunneling in Soft Soils. Proceedings of Underground Construction, June 3-5, [Internet]. 2019. Publisher's Version
Bouatia M, Demagh R. Effect of the initial soil suction on Structures Buried in an Expansive Soil during a Rainfall Infiltration Case of Aine-Tine pipeline. First International Congress on Advanced Geotechnical Engineering and Construction Management (ICAGECM’19), 9-10 December. 2019.
Beghloul M, Demagh R. Prediction of surface trough due to shield tunnelling. The XVII European Conference on Soil Mechanics and Geotechnical Engineering, 1-6 September, [Internet]. 2019. Publisher's VersionAbstract
In this study, the surface settlement induced by shield TBM excavation is simulated by using finite differences code Flac-3D. The proposed three dimensional simulation procedure is taking into account the main features of slurry shield TBM. The line D subway project in Lyon is chosen to validate the numerical simulations. The comparison of the numerical simulation results with the in-situ measurements shows that the proposed 3D simulation is relevant, in particular in the adopted representation for the different operations achieved by the tunnel boring machine.
Beghoul M, Demagh R. Slurry Shield Tunneling in Soft Ground-Comparison between Field Data and 3D Numerical Simulation. Studia Geotechnica et Mechanica [Internet]. 2019;41 (3) :115 - 128. Publisher's VersionAbstract
In urban areas, the control of ground surface settlement is an important issue during shield tunnel-boring machine (TBM) tunneling. These ground movements are affected by many machine control parameters. In this article, a finite difference (FD) model is developed using Itasca FLAC-3D to numerically simulate the whole process of shield TBM tunneling. The model simulates important components of the mechanized excavation process including slurry pressure on the excavation face, shield conicity, installation of segmental lining, grout injection in the annular void, and grout consolidation. The analysis results from the proposed method are compared and discussed in terms of ground movements (both vertical and horizontal) with field measurements data. The results reveal that the proposed 3D simulation is sufficient and can reasonably reproduce all the operations achieved by the TBM. In fact, the results show that the TBM parameters can be controlled to have acceptable levels of surface settlement. In particular, it seems that moderate face pressure can reduce ground movement significantly and, most importantly, can prevent the occurrence of face-expected instability when the shield crosses very weak soil layers. The shield conicity has also an important effect on ground surface settlement, which can be partly compensated by the grout pressure during tail grouting. Finally, the injection pressure at the rear of the shield significantly reduces the vertical displacements at the crown of the tunnel and, therefore, reduces the settlement at the ground surface.
Beghoul M, Demagh R. Surface settlement induced by shield tunneling–complete 3D numerical simulation on two case studies. The WTC 2019 ITA-AITES World Tunnel Congress (WTC 2019), May 3-9, [Internet]. 2019. Publisher's Version

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