Infrastructure Engineering - Research Publications

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    Formulas for Uniaxial Capacities of Tetrapod Bucket Foundations Considering Group Effects in Undrained Clay
    Xiao, Z ; Wang, Y ; Liu, Y ; Tian, Y ; Wang, R ; Tao, R ; Wei, X (MDPI, 2022-06-01)
    Suction bucket foundation is a novel and cheaper foundation used in marine structures, such as offshore wind turbines, breakwater and oil platforms. Compared with a single bucket foundation, tetrapod bucket foundations can bear larger loads because of the group effects. However, the vertical, horizontal and moment capacity factors of tetrapod bucket foundations have not been presented in existing specifications. A series of three-dimensional finite-element analyses were conducted to investigate the group effects on uniaxial capacities and failure mechanisms of tetrapod bucket foundations in undrained clay considering various foundation separation distance ratios, embedment depth ratios, soil-strength heterogeneity indices and load direction angles. Generalized formulas for undrained uniaxial capacities of tetrapod bucket foundations were proposed in order to establish a bridge connecting the capacities of tetrapod bucket foundations and those of the single bucket foundation, which can provide a reference for industrial designs of capacities of tetrapod bucket foundations. The results show that the vertical group effect factor of tetrapod bucket foundations is basically not affected by the foundation separation distance ratio, embedment depth ratio, soil-strength heterogeneity index and load direction angle, which can adopted 0.9 based on a conservative estimation. The normalized horizontal and moment group effect factors of tetrapod bucket foundations are both affected by the separation distance ratio, embedment depth ratio and soil-strength heterogeneity index, but the moment group effect factor is also obviously affected by the load direction angle. The value of the horizontal and moment capacity factors of tetrapod bucket foundations are about 2.3 and 13.8 times that of a single bucket foundation, respectively, when the separation distance ratio is 3.5, embedment depth ratio is 1.0 and soil-strength heterogeneity index is 10, which have both been significantly enhanced. A value of 3.5 is suggested for the separation distance ratio to attain good capacities and a relatively high global stiffness for the tetrapod bucket foundations.
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    A Technology Assessment Approach for Achieving Sustainable Communities: An Energy Master Plan for a New Urban Development
    Santillan, MR ; Syn, JW ; Shandiz, SC ; Huang, Y ; de Lacerda, MP ; Rismanchi, B (MDPI, 2022-04-01)
    In the era of climate change and rapid urbanisation, communities and infrastructures need to be planned and designed in a way that promotes sustainable living. The provision of clean and affordable energy is a key to this aim. This paper proposes a technology assessment approach that is based on the triple bottom line (environmental, social and economic) sustainability framework. This approach can be employed in the technology screening that is involved in the early stages of the energy master planning process and can be applied to different community typologies in various locations and climates. The developed approach is demonstrated through a new urban renewal project case study in Fishermans Bend, Melbourne, in which a set of technological options were screened according to the project’s goals. The connection between the energy master plan and local and global sustainable development goals is discussed and policy interventions are proposed. The results show that the proposed approach could effectively enable the evaluation of the technological sustainability performance of the community by demonstrating the design trade-offs and the implementation of the sustainability objectives during the energy master planning process. Moreover, the proposed approach could provide guidance for effective policy making. It was found that government energy policies, regulations and incentives play a vital role in the feasibility of an energy master plan. Lastly, the proposed approach could facilitate the achievement of local and international targets, such as the UN SDGs, by 2050.
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    Impact of Vertical Atmospheric Structure on an Atypical Fire in a Mountain Valley
    Ozaki, M ; Harris, RMB ; Love, PT ; Aryal, J ; Fox-Hughes, P ; Williamson, GJ (MDPI, 2022-08-01)
    Wildfires are not only a natural part of many ecosystems, but they can also have disastrous consequences for humans, including in Australia. Rugged terrain adds to the difficulty of predicting fire behavior and fire spread, as fires often propagate contrary to expectations. Even though fire models generally incorporate weather, fuels, and topography, which are important factors affecting fire behavior, they usually only consider the surface wind; however, the more elevated winds should also be accounted for, in addition to surface winds, when predicting fire spread in rugged terrain because valley winds are often dynamically altered by the interaction of a layered atmosphere and the topography. Here, fire spread in rugged terrain was examined in a case study of the Riveaux Road Fire, which was ignited by multiple lightning strikes in January 2019 in southern Tasmania, Australia and burnt approximately 637.19 km2. Firstly, the number of conducive wind structures, which are defined as the combination of wind and temperature layers likely to result in enhanced surface wind, were counted by examining the vertical wind structure of the atmosphere, and the potential for above-surface winds to affect fire propagation was identified. Then, the multiple fire propagations were simulated using a new fire simulator (Prototype 2) motivated by the draft specification of the forthcoming new fire danger rating system, the Australian Fire Danger Rating System (AFDRS). Simulations were performed with one experiment group utilizing wind fields that included upper-air interactions, and two control groups that utilized downscaled wind from a model that only incorporated surface winds, to identify the impact of upper air interactions. Consequently, a detailed analysis showed that more conducive structures were commonly observed in the rugged terrain than in the other topography. In addition, the simulation of the experiment group performed better in predicting fire spread than those of the control groups in rugged terrain. In contrast, the control groups based on the downscaled surface wind model performed well in less rugged terrain. These results suggest that not only surface winds but also the higher altitude winds above the surface are required to be considered, especially in rugged terrain.
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    A Framework for Scaling Urban Transformative Resilience through Utilizing Volunteered Geographic Information
    Moghadas, M ; Rajabifard, A ; Fekete, A ; Koetter, T (MDPI, 2022-02-01)
    Resilience in the urban context can be described as a continuum of absorptive, adaptive, and transformative capacities. The need to move toward a sustainable future and bounce forward after any disruption has led recent urban resilience initiatives to engage with the concept of transformative resilience when and where conventional and top-down resilience initiatives are less likely to deliver effective strategies, plans, and implementable actions. Transformative resilience pathways emphasize the importance of reflexive governance, inclusive co-creation of knowledge, innovative and collaborative learning, and self-organizing processes. To support these transformative pathways, considering techno-social co-evolution and digital transformation, using new data sources such as Volunteered Geographic Information (VGI) and crowdsourcing are being promoted. However, a literature review on VGI and transformative resilience reveals that a comprehensive understanding of the complexities and capacities of utilizing VGI for transformative resilience is lacking. Therefore, based on a qualitative content analysis of available resources, this paper explores the key aspects of using VGI for transformative resilience and proposes a comprehensive framework structured around the identified legal, institutional, social, economic, and technical aspects to formalize the process of adopting VGI in transformative resilience initiatives.
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    Viscoelastic Wave–Ice Interactions: A Computational Fluid–Solid Dynamic Approach
    Tavakoli, S ; Huang, L ; Azhari, F ; Babanin, AV (MDPI AG, 2022-09-01)
    A computational fluid–solid dynamic model is employed to simulate the interaction between water waves and a consolidated ice cover. The model solves the Navier–Stokes equations for the ocean-wave flow around a solid body, and the solid behavior is formalized by the Maxwell viscoelastic model. Model predictions are compared against experimental flume tests of waves interacting with viscoelastic plates. The decay rate and wave dispersion predicted by the model are shown to be in good agreement with experimental results. Furthermore, the model is scaled, by simulating the wave interaction with an actual sea ice cover formed in the ocean. The scaled decay and dispersion results are found to be still valid in full scale. It is shown that the decay rate of waves in a viscoelastic cover is proportional to the quadratic of wave frequency in long waves, whilst biquadrate for short waves. The former is likely to be a viscoelastic effect, and the latter is likely to be related to the energy damping caused by the fluid motion. Overall, the modeling approach and results of the present paper are expected to provide new insights into wave–ice interactions and help researchers to dynamically simulate similar fluid–structure interactions with high fidelity.
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    Optimized Design of Piled Embankment Using a Multi-Effect Coupling Model on a Coastal Highway
    Zhang, A ; Liao, J ; Liu, Z ; Zhou, C ; Zhang, L (MDPI, 2022-09-01)
    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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    Experimental Study of Wave-Induced Response of Piles in Seabed with Various Permeability
    Huang, T ; Tian, Y ; Dai, G ; Jiao, A (MDPI AG, 2022-03-01)
    Subjected to continuous wave loading, the responses of pile foundations and seabed develop gradually, severely affecting the serviceability of piled structures. This paper presents the results of a series of flume experiments on pile foundations in fine sandy and silty seabed under regular wave loading. Pile-head displacement and pore water pressure were measured and the effects of pile diameter, cross-section, pile stiffness and wave height were investigated. The experimental results indicate that the pore pressure in fine sandy seabed varied only slightly even under 640 s of wave loading but showed an increase of 15.7–25.9% around a pile. In silty seabed with much lower permeability, pore pressure accumulated quickly due to piles and oscillated impressively at the depth of soil liquefaction. Based on the comparison between the calculated and measured pile-head displacement, we found that the response of smaller-diameter piles in lower-permeability seabed was much more easily magnified by the induced pore pressure. Increasing the pile diameter and attaching fins could lead to a smaller response of piles. Wave height was a major factor in the experiments that affected the development of response.
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    Percolation Threshold of Red-Bed Soft Rock during Damage and Destruction
    Yu, L ; Lai, H ; Zhou, C ; Liu, Z ; Zhang, L (MDPI, 2022-08-01)
    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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    Epistemic Uncertainties in the Assessment of Regional Soil Acidification
    Benke, K ; Robinson, N ; Norng, S ; Rees, D ; O’Leary, G (MDPI AG, 2022-08-01)
    The increasing acidification of soil due to pollution and agricultural management practices is a growing problem worldwide, where food production is already under threat by climate change, more frequent droughts, and soil nutrient depletion. Soil acidification is quantified by pH measurements and is a primary metric for soil health. High soil acidity is a constraint on the production of grains and other crops because it decreases the bioavailability of important plant nutrients while increasing soil toxicity arising from an imbalance of essential soil elements. Field pH can be estimated by colour test kits which are very cost-effective and particularly suitable for developing countries where laboratory services are not available or fail to provide timely results. Because the pH test kit is based on visual colour matching between a colour card scale and a soil sample in solution, there are epistemic uncertainties, such as variability in expert opinion, differences in colour vision, measurement error, instrumentation, and changes in daylight spectral content. In this study, expert human observers were compared in experiments conducted using a standard pH test kit under a range of environmental conditions. A significant difference in uncertainty in colour discrimination was evident between male and female experts, whereas changes in daylight conditions had lower impact on the variance of pH estimates. In a group of subject matter experts, the male standard error (0.35 pH) was 57% higher on average over the range of pH values (pH = 4 → 10) compared to females (0.22 pH). This error was largest (70%) in the low pH 4 to 6.5 range, which is a critical range for successful amelioration of soil acidification. The results suggest that historical database measurements may have hitherto unrecognised uncertainties that affect confidence intervals for experimental data that in turn will have an impact on predictive models and policy development.
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    Analytical Framework for Understanding the Differences between Technical Standards Originating from Various Regions to Improve International Hydropower Project Delivery
    You, R ; Tang, W ; Duffield, CF ; Zhang, L ; Hui, F ; Kang, Y (MDPI, 2022-02-01)
    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.