ORCID Profile
0000-0002-6473-8712
Current Organisation
Memorial University of Newfoundland
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Publisher: Elsevier BV
Date: 02-2022
Publisher: Elsevier BV
Date: 09-2021
Publisher: Canadian Science Publishing
Date: 08-2023
Abstract: The gradual trench formation of steel catenary risers (SCRs) in the touchdown zone is known to significantly affect the SCR’s fatigue life. However, there is still no coherent agreement among researchers on the beneficial or detrimental effects of the trench on fatigue. Recent studies have shown that a potential source of contradictory fatigue results could be the methodology to incorporate the trench in the numerical simulations. Since the predefined mathematical trench profiles create non-realistic contact pressure hot spots in the seabed, and the nonlinear hysteretic seabed interaction models may cause premature trench stabilization, both methods distort the damage distribution. To resolve these problems, a new model called the Hybrid Trench Model (HTM) has been developed in this study by combining the linear soil stiffness and nonlinear hysteretic seabed interaction model. This hybrid model provides an equivalent stiffness distribution in the touchdown zone to simulate the trench profile obtained from a nonlinear riser–seabed interaction model. HTM’s capability in developing deep trenches, e.g., 5D, was examined along with perfect compatibility with the natural catenary shape of the riser, exhibiting the reliability of this method to incorporate the trench effect into the fatigue analysis.
Publisher: Elsevier BV
Date: 12-2022
Publisher: Elsevier BV
Date: 12-2022
Publisher: MDPI AG
Date: 08-11-2022
DOI: 10.3390/W14223593
Abstract: Climate change-driven forces and anthropogenic interventions have led to considerable changes in coastal zones and shoreline positions, resulting in coastal erosion or sedimentation. Shoreline change detection through cost-effective methods and easy-access data plays a key role in coastal management, where other effective parameters such as land-use/land-cover (LULC) change should be considered. This paper presents a remotely sensed shoreline monitoring in Sandbanks Provincial Park, Ontario, Canada, from 1984 to 2021. The CoastSat toolkit for Python and a multilayer perceptron (MLP) neural network classifier were used for shoreline detection, and an unsupervised change detection framework followed by a postclassification change detection method was implemented for LULC classification and change detection. The study assessed the recent coastal erosion and accretion trends in the region in association with spatiotemporal changes in the total area of the West and East Lakes, the transition between LULC classes, extreme climate events, population growth, and future climate projection scenarios. The results of the study illustrate that the accretion trend apparently can be seen in most parts of the study area since 1984 and is affected by several factors, including lake water-level changes, total annual precipitations, sand movements, and other hydrologic/climatic parameters. Furthermore, the observed LULC changes could be in line with climate change-driven forces and population growth to accelerate the detected accretion trend in the East and West Lakes. In total, the synergistic interaction of the investigated parameters would result in a greater accretion trend along with a lower groundwater table amid even a low carbon scenario. The discussed findings could be beneficial to regional rovincial authorities, policymakers, and environmental advocates for the sustainable development of coastal communities.
Publisher: Elsevier BV
Date: 12-2022
Publisher: American Society of Civil Engineers (ASCE)
Date: 08-2021
Publisher: Informa UK Limited
Date: 11-03-2021
Publisher: Elsevier BV
Date: 12-2022
Publisher: Elsevier BV
Date: 12-2021
Publisher: Springer Science and Business Media LLC
Date: 17-02-2021
Publisher: American Society of Civil Engineers (ASCE)
Date: 06-2023
Publisher: Elsevier BV
Date: 06-2023
Publisher: Informa UK Limited
Date: 28-12-2020
Publisher: Canadian Science Publishing
Date: 09-05-2023
Abstract: This study presents a numerical investigation of free field ice gouging in layered cohesive seabeds comprising stiff over soft clay. A three-dimensional, half-space, dynamic large deformation finite element (LDFE) analysis was conducted using the Coupled Eulerian Lagrangian (CEL) approach. To simulate the seabed, a Tresca soil model with the strain rate and strain-softening effects was coded into a user subroutine. The accuracy of the model was verified by comparing its results with those of published experimental studies. Additionally, a comprehensive parametric study was conducted to examine the effect of various ice gouging scenarios and seabed soil parameters on the subgouge soil deformation and the ice keel reaction forces. Our findings revealed that an interactive response occurs between the soil layers and the ice keel that may cause the peak subgouge soil deformation and keel reaction magnitudes to differ from those observed under uniform soil conditions. The developed model was found to be an efficient tool for free field ice gouging analysis in cohesive layered seabeds.
Publisher: Elsevier BV
Date: 06-2021
Publisher: MDPI AG
Date: 31-01-2023
DOI: 10.3390/GEOSCIENCES13020047
Abstract: Trenched pipelines may experience significant lateral displacement due to natural geohazards such as strike slip-fault movements, landslides, etc. Using pre-excavated soil to backfill trenches is a cost-effective option to protect pipelines against large deformations. These backfilling materials are heavily remolded and therefore softer than the native ground. Therefore, the shear strength difference between the backfill and native ground may affect the pipeline–backfill–trench interaction and the failure mechanism of the surrounding soil. By assuming a simplified uniform soil domain, the influence of softer pre-excavated backfilling material on the pipeline–backfill–trench interaction is neglected in the analytical methods that are usually used in the structural health monitoring of buried pipelines. In this study, the effects of trenching and backfilling were incorporated into an analytical solution for a fast assessment of the pipeline response at the early stages of engineering design projects and structural health monitoring. In comparison with other methods, this methodology provides a convenient and efficient method for computing pipeline strain and deflection curves in geohazardous regions.
No related grants have been discovered for Hodjat Shiri.