Civil and Environmental Engineering - Journal articles
Permanent URI for this collection
Browse
Recent Submissions
Item A low-carbon electricity transition for small island developing states: The case of Mauritius(Elsevier Ltd., 2024-12-20) Jaggeshar, Doorgeshwaree; Mao, Xianqiang; Guo, Zhi; Zusman, Eric; Tu, Kevin; Chen, Xing; Ma, Zhiyuan; Global Energy Interconnection GroupA clean energy transition can not only help rebuild the energy landscape of small island developing states (SIDS) but also boost their resilience and long-term development prospects. This study employs the Open-Source Energy Modeling System (OSeMOSYS) model to analyze low-carbon transition pathways for Mauritius, which are aligned with its nationally determined contribution (NDC) objectives to increase renewable energy to 60 % and phase out coal by 2030. The study applied key performance indicators to assess this pathway against energy self-sufficiency, economic, environmental and social criteria. The study showed that renewable energy sources, namely, solar, biomass, wind and waste-to-energy, can be game-changers for the island. The optimal transition pathway would achieve a renewable target of 76.8 % and reduce CO2 emissions by more than 67 % across the modeling period at an estimated cost of 1.94 billion USD by 2040. Finally, the study evaluated the implications of Mauritius' clean transition in terms of its effects on green jobs as well as whether there is sufficient infrastructure, administrative and financial capacity and energy pricing policies to support the optimal pathway. The study concludes that the experience modeling a low-carbon transition pathway for Mauritius could also offer useful lessons for other SIDS contemplating similar transitions.Item Prediction of load-bearing capacity of FRP-steel composite tubed concrete columns: Using explainable machine learning model with limited data(Elsevier Ltd., 2024-12-03) Liu, Xiaoyang; Sun, Guozheng; Ju, Ruiqing; Li, Jing; Li, Zili; Jiang, Yali; Zhao, Kai; Zhang, Ye; Jing, Yucai; Yang, Guotao; Natural Science Foundation of Shandong ProvinceThe complex interaction mechanism between the FRP jacket, steel tube, and confined concrete in the FRP-steel composite tubed concrete (F-STC) column makes the prediction of its mechanical behaviour a challenging task. This paper specifically investigates the application of machine learning models to predict the load-bearing capacity of F-STC columns. Since relatively few experimental works are performed on F-STC columns, the database established based on the test results from previous research contains only 69 data samples. In order to circumvent the training difficulties caused by the relatively small database, the application of the Gaussian process regression (GPR) model is trialled in this study. To make the predictions of the GPR model explainable, the Shapley additive explanations (SHAP) approach is incorporated with the GPR model in this study. Besides, four contrasting prediction models based on artificial neural network (ANN), support vector regression (SVR), decision tree (DT), and random forest (RF), are also proposed. The k-fold validation and test results indicate that the GPR model provides strong potential in predicting the load-bearing capacity of F-STC columns with high prediction accuracy and generalisation capability. Besides, 95 % and 99 % confidence intervals obtained by the GPR model are provided to show the uncertainty of the prediction results. Furthermore, the effect of the database size on the prediction performance of GPR, ANN, and SVR models is further examined by gradually reducing the number of data samples, and the comparisons illustrate the superiority of the GPR model.Item The impact of thermal–hydraulic variation on tunnel long-term performance: a tale of two tunnels(ICE Publishing; ICE Publishing collections are provided by Emerald Publishing, 2024-09-28) Wang, Chao ; Xiao, Zhipeng ; Di Murro, Vanessa ; Osborne, John; Friedman, Miles ; Li, Zili ; Irish Research Council; Horizon 2020; H2020 Marie Skłodowska-Curie Actions; Science Foundation Ireland; Transport Infrastructure IrelandLong-term structural performance of ageing tunnels is influenced by various natural and anthropogenic factors. This study examines the impacts of two rarely investigated climatic factors: rainfall and temperature. Two dedicated case studies were conducted on the European Organisation for Nuclear Research (CERN) TT10 tunnel and Dublin port tunnel (DPT) using distributed fibre optic strain sensing (DFOS) and wireless sensor network (WSN) monitoring, respectively. DFOS data showed an increasing deformation in TT10 tunnel, attributed to tunnel deteriorations and ground deformation, with seasonal variation of lining strains linked to rainfall-related seasonal change in pore water pressure. However, inconsistencies in the rainfall–strain correlation were also noted due to geological complexities and varying pore water pressure sources. In contrast, WSN measurements showed that DPT deformation correlated with temperature, instead of precipitation. DPT deformation increased in warmer seasons and decreased in colder ones, in the absence of external disturbances, comprising reversible thermal deformation and irreversible deterioration-induced deformation. Over time, cyclic and periodic temperature changes caused elastic deformation to reverse, while plastic deformation accumulated, leading to ongoing tunnel deformation. These findings bring more insights into the resilience of critical underground infrastructure vulnerable to climate change, groundwater variations and other environmental factors.Item Modelling the impact of deterioration on the long-term performance of Dublin Tunnel(Canadian Science Publishing, 2024-09-11) Wang, Chao; Xiao, Zhipeng; Friedman, Miles; Li, Zili; Science Foundation Ireland; Transport Infrastructure Ireland; National Natural Science Foundation of ChinaThe influence of tunnel deteriorations on its long-term performance has received extensive attention recently. Most studies considered deteriorations by manually varying the magnitude of parameters like permeability and stiffness, neglecting their time-dependent variation. This paper addresses this gap by investigating the impact of time-dependent deteriorations on the long-term behaviour of the aging Dublin Port Tunnel (DPT). A modified analytical relative ground-lining permeability model and calculated deteriorated permeability for DPT were presented, with steps and procedures generalised. The deteriorated permeability was incorporated into the hydraulic deterioration model, together with mechanical deterioration, offering a more holistic and realistic prediction of DPT’s long-term performance than previously available. Numerical results, compared against field measurements, showed (1) assuming constant permeability fails to accurately capture time-dependent liner deformation, and hydraulic deterioration is the dominant factor inducing an approaching squatting deformation mode; (2) continuous mechanical deterioration leads to a linear growth in vertical and horizontal convergence over time, with vertical convergence being more pronounced, indicating a squatting contraction deformation mode; (3) the comparison quantitatively evaluates the impact of individual and coupled hydro-mechanical deterioration on DPT’s long-term behaviour and the agreement between field data and numerical results confirms coupled lining deterioration is the root cause behind the observation.Item Investigation of aero-hydro-elastic-mooring behavior of a H-type floating vertical axis wind turbine using coupled CFD-FEM method(Elsevier Ltd., 2024-07-02) Liu, Qingsong; Bashir, Musa; Iglesias, Gregorio; Miao, Weipao; Yue, Minnan; Xu, Zifei; Yang, Yang; Li, Chun; National Natural Science Foundation of ChinaFloating vertical axis wind turbines (VAWTs) are being explored as a promising new option for harnessing offshore wind energy due to their unique advantages, including low installation and maintenance costs, high operational efficiency in wind farm clusters, and scalability of rotor sizes. However, the lack of software capable of simulating the aeroelastic of VAWTs poses a significant barrier to their further development and deployment. The aim of this paper is to develop a fully coupled aero-hydro-elastic-mooring-material model for floating VAWTs. The aerodynamic performance, hydrodynamic response and structural nonlinearities of the floating VAWT are analyzed in detail using Computational Fluid Dynamics (CFD) and the Finite Element Method (FEM). The results indicate that: (i) The dynamic response of the floating VAWT platform results in more pronounced fluctuations in the power coefficient, characterized by frequent spike-like extreme values, compared to fixed VAWT. Nevertheless, wake dissipation in floating VAWT is quicker, facilitating faster flow recovery and a more marked acceleration effect in the flow field. (ii) The surge and pitch motions of the platform affect the velocity of the blades relative to the fluid, resulting in additive and subtractive effects with the incoming flow. This interaction gives the blade torque of the floating VAWT an alternating performance advantage in the upwind region, compared to fixed VAWT; (iii) Stress analysis reveals that the highest levels of stress occur at the juncture between the support arm and the blade, with significant stress also present at the bottom of the central pontoon. In contrast, the blade tips exhibit the lowest stress levels. (iv) The blades of the floating VAWT undergo radial deformation due to wind loads and centrifugal forces, while the support arms experience vertical vibrations, driven by their own weight combined with that of the blades. (v) The mooring lines, particularly influenced by platform traction and frequent interactions with the seabed, show dynamic shifts in maximum contact pressures, especially between moorings C2 and C3. Mooring C2, located on the windward side, consistently faces more intense seabed interactions.