Infrastructure Engineering - Research Publications
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ItemModeling consolidation of soft clay by developing a fractional differential constitutive model in conjunction with an intelligent displacement inversion method(PUBLIC LIBRARY SCIENCE, 2022-09-30)Studying the constitutive relation of soft clays is of critical importance for fundamentally understanding their complex consolidation behavior. This study proposes a fractional differential constitutive model in conjunction with an intelligent displacement inversion method based on the classic particle swarm optimization for modeling the deformation behavior of soft clay. The model considered the rheological properties of soft clay at different consolidation stages. In addition, statistical adaptive dynamic particle swarm optimization-least squares support vector machines were implemented to identify the model parameters efficiently. The accuracy and effectiveness of the model were validated using available experimental results. Finally, the application results showed that the proposed model could efficiently simulate coupling properties of soft clay's primary and secondary consolidations.
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ItemNo Preview AvailableInfluences of variability and uncertainty in vertical and horizontal surface roughness on articular cartilage lubrication(PERGAMON-ELSEVIER SCIENCE LTD, 2022-09)BACKGROUND AND OBJECTIVES: Cartilage surface roughness has significant implications on joint lubrication. However, the effects of the variability in surface roughness in different directions (especially in horizontal direction) in mixed-mode lubrication have not been fully investigated and relevant research work in this field is limited. This study presents a probabilistic numerical approach to investigate the influence of variability and uncertainty of Root-Mean-Square (RMS) roughness heights (vertical roughness) and roughness correlation lengths (horizontal roughness) on cartilage lubrication. METHODS: The synthetic surface topographies with typical ranges of vertical and horizontal roughness characteristics were firstly input to a coupled cartilage contact model. A response surface was then constructed using the input roughness parameters and the output coefficient of friction (CoF). Finally, a large number of independent or correlated roughness samples were generated for computing the probability of mixed-mode lubrication failure (PoF), which was defined as CoF > 0.27 (corresponding to a 90% loss of fluid support in the contact interface). RESULTS: Both independent RMS roughness heights and correlation lengths are correlated positively with CoF. This indicates that the increase of the vertical surface roughness could exacerbate cartilage wear, whereas increasing surface roughness in horizontal direction (i.e., reducing correlation lengths) could retain gap fluid that aids mixed-mode lubrication. Importantly, it shows that CoF is dominant by RMS roughness height. The uncertainty in the independent correlation lengths may lead to the underestimation of PoF. By simulating osteoarthritic surface roughness with a strong correlation between RMS roughness heights and correlation lengths, the value of PoF could reach 70-99%. CONCLUSION: This study highlights the significance of incorporating the mutual relations between the surface roughness in vertical and horizontal directions into research, and the findings could potentially contribute to the design of biomimetic cartilage surfaces for the treatment of osteoarthritis.
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ItemOptimized Design of Piled Embankment Using a Multi-Effect Coupling Model on a Coastal Highway(MDPI, 2022-09)This study presents a multi-effect coupling model to optimize the design of a geosynthetic-reinforced pile-supported embankment (GRPSE) considering the coupling effects of soil arching, membranes, and pile–soil interaction on a coastal highway. The developed model could optimize the design of the GRPSE to fulfill the design and construction requirements at a relatively low project cost. This was achieved by adjusting the critical factors that govern the settlement of GRPSEs, such as pile spacing, tensile stiffness of geosynthetic reinforcement (GR), arrangement of piles, pile cap size, and cushion thickness. The model predictions were validated by a series of field tests using a range of geotechnical sensors. The results show that model predictions agreed with experimental measurements reasonably well. In addition, the results indicate that in comparison to a square arrangement of piles, a triangle net arrangement can decrease the differential settlement of pile soil. Furthermore, this study demonstrates that a change in the GR’s tensile stiffness has little impact on the settlement of GRPSEs. This study can help to improve the stability of roadbeds of coastal highways.
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ItemPercolation Threshold of Red-Bed Soft Rock during Damage and Destruction(MDPI, 2022-08)The critical damage point of the red-bed soft rock percolation phenomenon can be described as the percolation threshold. At present, there are insufficient theoretical and experimental studies on the percolation phenomenon and threshold of red-bed soft rock. In combination with theoretical analysis, compression experiment and numerical simulation, the percolation threshold and destruction of red-bed soft rock are studied in this paper. The theoretical percolation threshold of red-bed soft rock was obtained by constructing a renormalization group model of soft rock. Based on damage mechanics theory, rock damage characterization and strain equivalent hypothesis, a constitutive model of red-bed soft rock percolation damage was obtained. The percolation threshold of red-bed soft rock was determined by compression test and a damage constitutive model, which verified the rationality of the theoretical percolation threshold, and we numerically simulated the percolation of red-bed soft rock under triaxial compression. The results showed that the percolation threshold increases as the confining pressure rises, but decreases significantly with the action of water. In this study, the critical failure conditions and percolation characteristics of red-bed soft rock under different conditions were obtained. The relationship between percolation and soft rock failure was revealed, providing a new direction for studying the unstable failure of red-bed soft rock.
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ItemAnalytical Framework for Understanding the Differences between Technical Standards Originating from Various Regions to Improve International Hydropower Project Delivery(MDPI, 2022-02)The international hydropower construction market is continuously growing during the past decade. The existing literature points out that contractors are facing ongoing difficulties in achieving the objectives of developing international hydropower projects, which largely arise from the misunderstanding and poor use of international technical standards. However, there is a lack of a coherent framework to help systematically analyze the differences between technical standards originating from various regions. This study establishes an analytical framework that incorporates the essential factors of technical standards, namely philosophy of standards, logical structure, completeness of standards, calculation method, equipment and material requirements, test method, construction method, and application conditions of standards, and demonstrates their relationships from a holistic perspective. With support of the data collected from Chinese contractors, the results revealed the application status of various technical standards and their differences. Hierarchical cluster analysis demonstrates that unfamiliarity with the differences between domestic and international technical standards can cause multiple problems in international hydropower project delivery, concerning applying international standards, integrated project management, design, procurement, and construction, which have broad theoretical and practical implications. The outcomes of this study can not only help contractors improve their capabilities of applying international standards for achieving superior international hydropower project performance, but also facilitate mutual recognition of the standards from various regions, thereby maximizing the effectiveness of global resources such as expertise, technologies, methods, and products.
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ItemApplication of a coupled hydro-mechanical interface model in simulating uplifting problems(WILEY, 2022-12)Abstract This paper presents the detailed formulation of a coupled hydro‐mechanical structure‐soil interface and demonstrates its application in simulating uplifting problems. This interface features real‐time prediction of the pore pressure generation and structure‐soil separation, and thus rate dependency and ‘breakaway’ can be modeled without user intervention. Constitutive relations of this interface were derived by considering the coupling between soil skeleton and fluid along the interface. A complete finite element formulation and numerical implementation of the interface is provided based on an eight‐node element. The performance of this interface is demonstrated by simulating lifting a surface footing at varying rates (spanning across undrained, partially drained and drained conditions), compared with existing theoretical solutions, numerical results and experimental data. The good agreement achieved indicates that this interface is capable of modelling uplift at varying rates, which is an extremely challenging topic in offshore engineering. Sensitivity studies were conducted to investigate the parameters affecting uplifting behaviour. A unified backbone curve was established correspondingly, which is shown to be different from existing studies in compression, due to the difference in the mechanism between the two cases.
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ItemIndentation into an aluminium panel by the impact of a rigid spherical object(Elsevier BV, 2022-11)This paper introduces algebraic expressions for determining the amount of permanent indentation caused to an aluminium panel when impacted by a rigid spherical object. The magnitude of indentation is observed to vary significantly with the position of impact within the panel when the impactor and the velocity of impact are kept the same. This spatial variation of indentation is caused by the changes in the combinational mass (which is in turn function of the participating mass of the plate) and the Coefficient of Restitution COR. Both parameters are shown to correlate with the position of impact. The proposed algebraic expression featuring the combinational mass and COR as input parameters, allows potential damage to the panel to be predicted conveniently in day-to-day engineering practices. The original contribution of this article is in illustrating this phenomenon analytically, and have the analytical predictions verified by impact experimentation which has been conducted by the authors on panels of varying dimensions.
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ItemNo Preview AvailableThe synthesis of soft rocks based on physical and mechanical properties of red mudstone(PERGAMON-ELSEVIER SCIENCE LTD, 2022-03)
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ItemNo Preview AvailableApplication of New Polymer Composite Materials in Rock Slope Ecological(IOP Publishing, 2021-10-27)