Research Articles (Civil Engineering)

Permanent URI for this collectionhttp://hdl.handle.net/2263/1701

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Bus rapid transit in Africa - is it still relevant?
Venter, Christoffel Jacobus (Routledge, 2026)
No abstract available.
Exploring mode choice behaviour and preferences of transport users in small cities in South Africa : the case study of Bloemfontein
Burger, Everardt André; Chetty, Alison (Palacký University Olomouc, 2026-03-23)
This study investigates mode choice behaviour and transport preferences in Bloemfontein, South Africa, a medium-sized metropolitan area facing distinct transportation challenges related to accessibility, affordability, and limited modal integration. While urban mobility research in South Africa has largely focused on major metropolitan regions, smaller cities such as Bloemfontein require tailored, context-sensitive strategies to address their specific economic, spatial, and social dynamics. Adopting a pragmatic research paradigm and guided by the Theory of Planned Behaviour (TPB), this study employs a structured quantitative research design and an Ordinal Logistic Regression Model to examine the factors shaping user preferences across private vehicle (PV), public transport (PT), and non-motorized transport (NMT) modes. Key predictors evaluated include accessibility, reliability, affordability, flexibility, and perceived health benefits. Data were collected through a structured survey targeting regular commuters across different demographic groups. Initial descriptive analysis revealed that demographic variables, particularly gender, age, and employment status, significantly influence transport choices. Women tended to prioritize safety and personal security, while men placed greater emphasis on reliability and on-road performance. Full-time employees showed stronger preferences for PV and PT, whereas part-time workers and unemployed respondents relied more heavily on NMT, reflecting differences in income levels, travel constraints, and daily activity patterns. Subsequent regression analysis confirmed that accessibility (ease of accessing a service) is the most significant predictor of mode choice, followed by service reliability and affordability. While safety concerns remain relevant, their influence was comparatively weaker than service quality and convenience factors. The findings further indicate a substantial willingness among PV users to shift to PT if improvements in reliability, flexible operating hours, and transparency of service information are implemented. The integration of NMT infrastructure, including pedestrian-friendly environments, bike-sharing programmes, and park-and-ride facilities, is identified as essential for strengthening first- and last-mile connectivity. Overall, the study provides empirically grounded, user-focused insights to inform transport policy and planning in smaller cities. By linking behavioural theory with quantitative evidence, the findings support targeted interventions aimed at enhancing PT accessibility, affordability, and reliability, thereby contributing to more inclusive, sustainable, and equitable urban transport systems.
A critical review of resilient modulus characterisation in unbound granular materials
Rugabandana, Gabriel; Boateng, Joseph Anochie; Maina, J.W. (James); Rimoy, Siya (Springer, 2026)
The resilient modulus (MR) is a fundamental parameter used to characterise the resilient response of unbound granular materials (UGMs), which are widely employed in the construction of flexible pavement systems. MR plays a pivotal role in estimating the stress-strain behavior of pavement layers under traffic loading and serves as a key control metric during construction and quality assurance processes. Moreover, it is critical in understanding the mechanisms behind common pavement distresses, including fatigue cracking and rutting. The primary objective of this study is to conduct a comprehensive literature review on the resilient behavior of UGMs, emphasizing the conceptual framework of MR, the key influencing factors, and the evolution of mathematical models developed to estimate and predict this mechanical property. The review concludes with insights into current research gaps and recommendations for future investigation. Despite significant research over the past decades, the resilient behavior of UGMs remains incompletely understood, largely due to the inherent heterogeneity of these materials and their nonlinear, anisotropic responses under varied cyclic loading paths and moisture conditions. The mechanical behavior of UGMs is influenced by both macroscopic and microscopic material characteristics, such as gradation, density, porosity, surface texture, mineralogical composition, particle shape, and orientation. Environmental conditions, particularly temperature fluctuations, also play a critical role. One major limitation of existing MR models is that their parameters are typically difficult to determine through experimentation and are not true intrinsic material constants. Instead, they act as state-dependent variables, influenced by stress level, moisture content, boundary conditions, and loading history. Furthermore, most models are calibrated using data from repeated load triaxial (RLT) tests, which fail to replicate the complex, multiaxial stress states experienced by UGMs in actual pavement structures especially the simultaneous action of vertical, horizontal, and shear cyclic stresses. While these studies have provided valuable insights, further research is needed to establish definitive conclusions and to enhance the predictive reliability of existing MR models.
Experimental comparison of rainfall simulation methods for urban stormwater management research
Van Zyl, Rachel Neleah; Loots, Ione (IWA Publishing, 2026-04-01)
Rainfall simulators are typically categorised as either pressurised or drop-forming systems, each offering distinct advantages depending on the research application. This study presents a comparative experimental analysis of a pressurised nozzle-based rainfall simulator and a drop-forming needle-based rainfall simulator, assessing their suitability for urban stormwater management research. Both setups were constructed indoors with a 1.5 × 1.5 m rainfall area and a 2.3 m raindrop fall height. The simulators were evaluated based on rainfall intensity, spatial uniformity, drop size distribution and drop velocity. The pressurised system produced intensities from 23.9 to 109.7 mm/h, while the drop-forming system achieved 4.5–21.0 mm/h. Uniformity coefficients ranged from 81.2 to 93.3% (cups) and 86.6 to 96.4% (trays) for the pressurised system, and 85.7% (cups) and 94.8% (trays) for the drop-forming system. D50 raindrop sizes ranged from 0.8 to 1.2 mm for the pressurised system and 1.7 mm for the drop-forming system. Estimated median drop velocities ranged from 82.5 to 98.5% of terminal velocity. While both systems replicated key rainfall characteristics, the pressurised simulator was limited to high-intensity events. The drop-forming simulator offered finer control and broader applicability, supporting its use in urban hydrology and stormwater management research. HIGHLIGHTS Experimental comparison of pressurised and drop-forming rainfall simulators under identical scale conditions. Drop-forming needle-based simulators offer finer control over rainfall intensity. A mesh in drop-forming rainfall simulators improves uniformity and drop size distribution. Results promote drop-forming rainfall simulator use in sustainable urban stormwater management research.
Estimating urban impervious surface connectivity to drainage systems in a developing country : field evidence from Tshwane, South Africa
Loots, Ione; Smithers, Jeffrey; Kjeldsen, Thomas Rodding (Taylor and Francis, 2026)
The connectivity of impervious areas to drainage systems, or directly connected impervious area (DCIA), is a key factor in urban runoff and water quality modelling, but is rarely measured in developing countries due to cost and complexity. This study provides new, visually observed field data on connectivity for 272 urban sites in Tshwane, South Africa, to support low-cost DCIA estimation across land use classes. Linear regression, logistic regression, and visual interpretation were used to estimate drainage connectivity. Results show that, contrary to findings from developed countries, most formal and informal residential areas exhibit 0% DCIA. In contrast, industrial and commercial sites show consistently high DCIA, aligning with international trends. These findings offer practical guidance for DCIA estimation in data-scarce urban environments: zero connectivity can be assumed for residential areas with total impervious area below 50%, with 100% DCIA for commercial/industrial sites.
The measured and modelled thermal response of reinforced concrete T-beams subjected to environmental loading
Kleynhans, Amé; Kearsley, Elsabe P.; Skorpen, Sarah Anne (South African Institute of Civil Engineers, 2025-12)
In this study, the thermal response of two reinforced concrete T-beams with identical outer dimensions but differing internal geometry, and therefore different thermal inertia, is investigated. Both T-beams were instrumented with thermocouples and vibrating wire strain gauges and subjected to purely thermal environmental loading. The weighted average (effective cross-sectional) temperature, along with the vertical and transverse temperature distributions, were analysed. In addition, theoretical thermal strains and self-equilibrating stresses were calculated. Uniquely, the mathematical model and assumptions were compared to and validated by experimentally measured strains as opposed to validation through comparisons of predicted temperatures. Effective temperature ranges were related to crosssectional area per unit width and compared to results from literature. Furthermore, the greatest difference in thermal response between the two sections was found to be effective temperature and subsequent longitudinal movement. Calculated bending moments, caused by thermal loading effects and self-equilibrating stresses, approached 30% of the concrete’s ultimate tensile capacity, emphasising their structural relevance.
Capacity-based feasibility boundaries for shared priority infrastructure for minibus taxis at signalised intersections
Mwenda, John Paul; Venter, Christoffel Jacobus (South African Institute of Civil Engineers, 2025-12)
The minibus taxi (MBT) is the most widely used mode of public transport in South Africa, accounting for over 66% of peak hour public transport trips. Unlike buses, which benefit from dedicated infrastructure such as bus rapid transit (BRT) lanes with priority transit signals at intersections, MBTs currently lack such priority infrastructure to enhance their efficiency. Efforts by South African road authorities to provide priority infrastructure for MBTs are hindered by the absence of technical guidance on planning, design, and feasibility. This study addresses this gap by developing an analytical method to determine feasible traffic volumes for shared queue bypass priority lanes at pre-timed signalised intersections. The basic problem is that any priority given to MBT vehicles likely reduces the capacity available to other vehicles, which could lead to performance losses. Taking account of this interaction between MBT and general traffic volumes and the reallocation of vehicles to different lanes, we define feasibility as the combination of volumes where capacity is not exceeded for either vehicle type while still offering potential delay savings for MBTs. We produce a set of graphs that can serve as an initial assessment of whether intersections with medium to high MBT volumes may qualify for priority treatment, considering only existing geometric and traffic characteristics. Additionally, the study provides guidance on expected storage lengths for these priority lanes. Overall, the findings indicate that shared queue bypass lanes are effective when medium taxi volumes (approximately 20 PCU/hr to 85 PCU/hr) are present, provided that turning traffic in the shared left-turn lane is not excessively high (between 50 PCU/hr and 640 PCU/hr, depending on green time). Noting that drivers may adapt to priority intersections in unknown ways, we recommend further studies on the traffic safety implications of priority treatments under real operating conditions.
Cross-laminated timber : a state-of-the-art review towards a proposed structural analysis strategy
Boulle, Benedict E.; Van der Merwe, Johann E., Van der Merwe, Johann E.; Roth, C.P. (Chris) (South African Institute of Civil Engineers, 2025-12)
Cross-laminated timber (CLT) has experienced growing global popularity in recent years, extending to South Africa with the adoption of SANS 8892 (2020), which allows for local manufacturing of performance-rated CLT. However, this standard requires all locally produced CLT layups to undergo extensive mechanical verification to determine strength and stiffness properties. Analytical methods have proven relatively accurate in predicting the out-of-plane mechanical properties of CLT. Incorporating these methods into design equations can aid in the structural design and sizing of CLT elements. The currently proposed prEN 1995-1-1 (2023) contains design factors specific to CLT, largely common with sawn timber. Adopting such an approach would simplify CLT design in South Africa, using established partial factors, as is the case for plywood. Resistance equations are therefore proposed using existing partial factors for sawn timber design in SANS 10163-1 (2003), incorporating Timoshenko beam theory calculations for bending and shear stresses in CLT. However, the material resistance factor value of 0.68 proposed for sawn timber may be overly conservative due to CLT’s inherent load-sharing behaviour. Using the methods outlined by Pagel (2019) and variability results of South African pine-only CLT obtained by Jacobs (2023), an average resistance factor of 0.79 was determined.
Application of cement-cassava peel ash mix for the stabilisation of marine clay soil : a review
Oruabena, Bernard; Steyn, Wynand Jacobus Van der Merwe (Springer, 2026)
This review investigated the application of cement and Cassava Peel Ash (CPA) for stabilising Marine Clay Soil (MCS). This material exhibits unusually high plasticity and compressibility and low shear strength, creating challenging conditions for stabilisation. In recent decades, lime and cement have been utilised to enhance the resilience of MCSs. However, the environmental and economic sustainability of this practice has come into question due to the substantial carbon dioxide emissions produced during cement manufacturing. Cement-free stabilisation using the scientifically innovative agricultural by-product CPA has been developed as an eco-friendly and cost-effective alternative, leveraging its improved pozzolanic activity to enhance the structural characteristics of MCS, such as strength, stiffness, and permeability. Although the combination of cement and CPA could significantly benefit the structural engineering of MCS, understanding the detailed mechanisms of cement-free stabilisation remains complex, limiting its widespread application. This review indicates that the CPA-cement mix can enhance key aspects of MCS, including permeability, California Bearing Ratio (CBR), and Unconfined Compressive Strength (UCS).
Lime stabilization of tropical soils : mechanical parameters for mechanistic–empirical pavement design
Kleinert, Thaís Radünz; Grimm, Henrique Falck; Núñez, Washington Pere; Visser, Alex T. (MDPI, 2026-02)
The mechanical behavior of lime-stabilized layers is essential for mechanistic–empirical pavement design, particularly in tropical regions where soil behavior differs from that of temperate residual soils. This study investigated three tropical soils (Argisol, Luvisol, and Latosol) stabilized with two hydrated lime sources (calcitic and dolomitic) at contents of 3% and 5%, compacted at standard or modified effort. Unconfined compressive strength (UCS) was measured at 7, 28, and 90 days, while flexural tensile strength (FTS) was obtained at 28 days, from which the flexural static modulus (FSM) and strain at break (εb) were derived. The results showed a strong soil-dependent response to lime treatment, with Argisol and Latosol behaving as lime-stabilized materials, whereas Luvisol exhibited more moderate improvements typical of soil modification. Compactive effort, lime type, and lime content significantly influenced UCS, FTS, and FSM, with compactive effort being the dominant and operationally achievable factor. Higher compactive effort, calcitic lime, and a 5% lime content consistently resulted in improved mechanical behavior, while curing time strongly influenced compressive strength due to progressive pozzolanic reaction. In contrast, strain at break was not significantly affected by the studied controllable factors and converged toward approximately 200 microstrain for soil–lime mixtures with UCS > 1 MPa, indicating a less brittle behavior relative to cement-stabilized materials and providing a representative input for preliminary design. Finally, significant correlations were established between UCS and FTS and between UCS and FSM, enabling the estimation of flexural parameters directly from compressive strength and supporting design simplifications when flexural testing is unavailable.
A critical review of the modelling and factors considered for permanent deformation of the unbound granular materials
Rugabandana, Gabriel; Boateng, Joseph Anochie; Maina, J.W. (James); Rimoy, Siya (Springer, 2026-02)
The elastoplastic behavior of Unbound Granular Materials (UGMs) under repeated loading plays a critical role in the performance and longevity of flexible pavements. This paper presents a comprehensive review of the permanent deformation modelling and factors considered in UGMs. The factors influencing resistance to permanent deformation such as stress magnitude, moisture content, gradation, density, porosity, particle morphology, mineralogical composition, are discussed, emphasizing their complex interdependence and impact on material behaviour. The study also examines the development and evolution of mathematical and empirical models used to predict permanent deformation under cyclic loading, highlighting that most existing models, primarily derived from repeated load triaxial (RLT) tests, remain empirical in nature, lack physical interpretation, and do not capture the true three-dimensional stress state experienced in the field. Rutting, the predominant distress mode in flexible pavements, arises from the accumulation of both elastic and plastic deformations across all pavement layers. Although numerous predictive models express accumulated strain as a function of load repetitions and deviator stress, they often neglect critical influences such as environmental conditions and shear strength of the subgrade. This review identifies limitations in current design practices and modeling approaches, provides insights into modern concepts in rutting analysis, and outlines future research needs for developing more mechanistic and physically meaningful models to predict the permanent deformation behavior of UGMs in pavements.
Inlet modifications for increased box culvert capacity : a numerical modelling approach
Giliomee, Thea Maria Dorothea; Loots, Ione; Van Dijk, Marco (IWA Publishing, 2026-02-15)
Inlet modifications applied to culverts can increase the culvert discharge capacity, which will help stormwater drainage systems adapt to larger flood events. Wingwalls and headwalls are already widely used as retaining structures. It is therefore feasible to optimise these inlet structures to increase culvert capacity. Building upon previous physical modelling research, this study evaluated a wider range of headwall and wingwall angle combinations to refine the findings. Headwalls and wingwalls were compared with rounded-edge box culvert inlets with the aim of improving capacity under inlet control. Numerical modelling was used to optimise wingwalls and headwalls and rounded-edge inlets, quantify their improvement, and verify the alignment of results with established references and guidelines. A 15° headwall with a 15° wingwall added to a box culvert improved the flow by up to 34% at a headwater depth of twice the culvert height (2D), or up to 26% at 1.2D. This solution provides the best balance between hydraulic performance and practical implementation. The largest improvement obtained by rounding the edges of a square box culvert is 30% at 2D. Inlet modifications provide a sustainable solution to increase culvert drainage capacity, which can mitigate flood risks. HIGHLIGHTS • Modified inlets can be used to adapt culverts to increased peak floods. • Numerical modelling presents an opportunity to test multiple combinations. • The smallest wingwall and headwall angles provide the greatest flow improvement. • Wingwalls and headwalls are more effective than rounded-edge inlets for box culverts. • Discharge capacity improvements were quantified for each inlet configuration.
Practical empirical estimation of evaporation for mining and industrial water balances : application to a South African process dam
Pretorius, Marita Johanna; Loots, Ione (IWA Publishing, 2026-02)
Direct measurement of evaporation at mining and industrial sites is highly accurate, but often prohibitively expensive, limiting its routine use in operational water balance modelling. This study evaluates a practical, cost-conscious approach for estimating daily evaporation using commonly applied empirical methods. Model performance was assessed by comparison with measured evaporation at both daily and aggregate scales. Among the methods tested, the Hargreaves equation provided a simpler yet sufficiently accurate alternative to the Penman–Monteith equation for operational applications. Sensitivity analysis showed that temperature is the dominant control on evaporation estimates for both methods, while solar radiation additionally influences Penman–Monteith estimates. Prioritising temperature and solar radiation measurements can substantially improve evaporation estimates where monitoring resources are limited. Local rainfall and wind measurements remain necessary to account for spatial variability and non-modelled losses. The results demonstrate that reliable evaporation estimates can be achieved using simplified empirical methods, supporting improved water balance assessments at mining and industrial sites where direct measurements are not feasible. HIGHLIGHTS • The Penman–Monteith and Hargreaves methods can accurately estimate evaporation in process dams. • The Hargreaves method is a practical, low-cost alternative requiring fewer inputs and simpler computation. • Accurate measurement of temperature and solar radiation is critical. • Prioritising key parameters enables reliable estimates under budget constraints.
The investigation of an agile mobile quadruped robot in forensic death scenes
Blumenthal, Ryan; Siyenga, Similo; Mostert, Jordan; Steyn, Wynand Jacobus Van der Merwe; Rossouw, Servaas Hofmeyr (Lippincott, Williams and Wilkins, 2026-03)
The Fourth Industrial Revolution has accelerated the integration of robotics and artificial intelligence (AI) into workplaces, creating opportunities to merge technology with real-world practice. In forensic pathology, workforce shortages and the dangers of investigating hazardous death scenes highlight the need for innovation. This study explored the use of a mobile, agile quadruped robot to investigate hanging death scenes, assessing its ability to navigate, capture evidence, and reduce human risk. The research focused on low-risk hanging death scenes as a starting point, with the aim of later extending to more hazardous environments such as chemical-related scenes, fire deaths, and mass disasters. The quadruped robot demonstrated advanced mobility, allowing routine inspection tasks and the collection of visual and environmental data with accuracy, safety, and frequency. The study reviewed existing literature on robotic applications in forensic investigations, developed an initial procedure for scene evaluation, and tested the approach on selected hanging cases. The findings discuss advantages, limitations, and lessons learned, offering insight into the potential role of robotics in forensic death scene work. While promising, technical and operational challenges remain before robotics can be fully integrated into routine forensic practice.
Increasing culvert hydraulic capacity for improved climate resilience : a physical modelling analysis
Giliomee, Maria Dorothea; Loots, Ione; Van Dijk, Marco (IWA, 2025-08)
Culverts often fail to handle increased flood peaks due to urbanisation and climate change. Modifying culvert inlets to increase discharge capacity can negate the need for additional culvert barrels or to rebuild the entire structure. Although some previous studies investigated hydraulic culvert improvements, this study is the first to test different combinations of headwall and wingwall angles, and the effect of aeration vents, to improve capacity of inlet-controlled culverts. This physical modelling study evaluates various modified box and circular culvert inlets, quantifies their impact on capacity, develops a coefficient for use in standard equations, and verifies the alignment of results with established references and guidelines. A 15° headwall with a 30° wingwall added to a box culvert or a rounded inlet edge for a circular culvert improved the flow by up to 34% at a headwater depth of twice the culvert height (2D), or up to 18% at 1.2D for box culverts and 24% at 1.2D for circular culverts. An air vent after the inlet had an insignificant influence on the capacity. A novel flow improvement coefficient was developed to calculate improved capacity with existing design equations. Culvert inlet improvements will reduce flood risks and contribute to sustainable drainage infrastructure.
Correlation between ambient air temperature and effective bridge temperature based on long-term field monitoring : a case study of a concrete girder bridge in South Africa
Adendorff, Jurie F.; Skorpen, Sarah Anne; Kearsley, Elsabe P. (American Society of Civil Engineers, 2026-03)
This study investigates the long-term thermal behavior of an RC twin spine-beam bridge, the Van Zylspruit Bridge, located in central South Africa. This research utilizes 9 years of field monitoring data, including over 11.5 million data points from 41 thermistors as well as local meteorological information, to establish appropriate design correlations between the environment and the bridge’s thermal response. This study found that the temperature specifications for both ambient air temperature (AAT) and effective bridge temperature (EBT) in the South African Bridge Code, TMH 7, were overly conservative for this specific bridge and location. For instance, the design 50-year return period minimum and maximum AAT corresponded to actual return periods of 3,675 and 595 years, respectively. Similarly, the design EBT limits showed significantly longer actual return periods. Ultimately, this study underscores the critical importance of using appropriate thermal material properties alongside locally relevant environmental data for thermal design of bridges and proposes an adapted method for determining design effective bridge temperatures based on local meteorological data.
Mitigating reflective cracking with open-graded bitumen-stabilized pavement overlays : a 5-year field study
Dias, Claudio Renato Castro; Nunez, Washington Peres; Fedrigo, William; Brito, Lelio Antonio Teixeira; Ceratti, Jorge Augusto Pereira; Visser, Alex T. (Taylor and Francis, 2026-01)
The Port of Rio Grande is located in Rio Grande do Sul, the southernmost Brazilian state. It is accessed via National Highway BR-392, paved with Portland cement concrete (PCC) in 1975. A few decades later, an asphalt concrete overlay was placed over the cracked concrete pavement. In 2019, a test section was constructed, incorporating an open-graded (permeable) cold bituminous emulsion mix (CBEM) layer over the existing pavement to mitigate reflective cracking. This study aimed to evaluate the behaviour of this bitumen-stabilized material (BSM) layer and its effectiveness in delaying crack reflection. Pavement monitoring was used to track the evolution of stiffness, rutting and cracking over five years. A mechanistic-empirical analysis was performed using the South African model for BSM, and the results were compared with field performance. The BSM layers maintained their structural capacity as an overlay on a PCC pavement, not showing excessive elastic deflection or rutting. The South African model tends to underestimate the lifespan of pavements incorporating open-graded BSM due to challenges in determining their cohesion in laboratory conditions. Surface condition analysis revealed that the asphalt mix placed over the BSM base exhibited only low-level cracking, demonstrating the effectiveness of open-graded BSM layers in mitigating reflective cracking.
Predicting the time-swell relationship of an unsaturated highly expansive clay using the heat equation
Murison, Ruan A.; Gaspar, Tiago Alexandre Valentim; Jacobsz, Schalk Willem; Heymann, Gerhard (Emerald, 2026-03)
Although extensive research and practical experience have established a good understanding of the magnitude of swell in unsaturated expansive clays due to wetting, significantly less is known regarding the time taken for the swelling strains to develop. This paper describes a mathematical model, based on analogies with conventional consolidation theory and the heat equation, to predict the time-dependent volume increase during swelling of an initially unsaturated expansive clay. A series of oedometer tests on a highly expansive clay was performed to determine the coefficients of swell used in the proposed model. The observed oedometer swelling curves showed good agreement with the theoretical relationship. The results were then used to predict swell over time in a layered centrifuge model constructed from the same clay. The predicted heave closely matched the observed result at any time over an 11-year swelling period in prototype time.
Unlocking hydropower's potential : retrofitting infrastructure and harnessing unconventional sources for clean energy transitions
Van Dijk, Marco; Gezer, Dogan; Rudolf, Pavel (IOP Publishing, 2025)
Hydropower holds a pivotal role within the water-energy nexus for facilitating the clean energy transition, particularly in unconventional and retrofit opportunities. As a renewable energy source, hydropower contributes to decarbonizing the energy sector while simultaneously supporting water management objectives. By integrating hydropower generation into existing infrastructure such as water supply systems, weirs, irrigation networks, and wastewater treatment facilities, synergies can be leveraged to optimize resource utilization and enhance system resilience. This further offers some options for diversifying the electricity mix and speeding up the clean energy transition. However, the complex interaction between water availability and energy production necessitates careful planning and adaptive strategies to mitigate risks associated with climate variability and changing demand patterns. Unlocking the potential of hydropower through these unconventional and retrofitting opportunities is thus instrumental in advancing sustainability goals and ensuring the success of clean energy transitions in the face of various challenges. By leveraging existing infrastructure and exploring innovative solutions, countries stand to significantly enhance its energy resilience and reduce its carbon footprint. Moreover, such initiatives align with broader international objectives, including the Paris Agreement's vision of transitioning to a zero-emission society by 2050 and the European Union's FIT for 55 targets. Under these considerations, this paper seeks to explore the potential of retrofitting existing infrastructure and harnessing unconventional hydropower sources with examples in Czechia, South Africa and Türkiye to address electricity shortages, mitigate carbon emissions, and contribute to the broader clean energy transition agenda. The insights gained from this analysis can inform policy frameworks, investment strategies, and technological innovations aimed at fostering sustainable energy practices.
Centrifuge tests on the consolidation behaviour of foundations under alternating loads
Ganal, Aljoscha; Jacobsz, Schalk Willem; Reul, Oliver (Emerald, 2025-01)
This paper presents the results from centrifuge tests on raft foundations and piled rafts in overconsolidated kaolin clay carried out in a beam centrifuge at the University of Pretoria. The foundations were subjected to unloading and reloading phases as well as to multiple consecutive groundwater drawdowns, simulating typical loading scenarios of structures in an urban environment. In order to investigate the time-dependent load-deformation behaviour of foundations, the settlement of the foundations, the pore water pressures at different depths and the axial strains in the piles, from which pile resistances were then derived, were measured continuously. In the tests, repeated groundwater drawdowns resulted in a settlement accumulation, with the increase in settlements decreasing with each repetition. The pile position within the pile group was found to have a major impact on the mobilised pile resistance. The position, however, became less significant as the load level increased. Furthermore, insights were gained concerning the load distribution within piled rafts during consolidation.

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