A theme running through the collection of papers in this issue is associated with the broader implications and impact of climate change on natural and engineered surfaces, influencing the resilience and stability of engineered surfaces from a macro to micro structural scale and the transport processes responsible. These issues have been part of the wider engineering and sustainability debate for a significant time and a number of specific challenges have been highlighted, recently reviewed by Kandalai et al., 2023, identify large scale impacts of failure or change in engineered properties driven by dynamics of the climate crisis.
My background in earth systems and environmental geochemistry has a focus on waste and resource recovery, the sustainability of urban environments. I continuously seek to understand the influence of human-disturbed environments on environmental quality including pollutant migration and mitigation of risk through remediation, treatment or exposure scenarios which need deeper evaluation. We are often only provided with an opportunity for a transient snapshot of conditions that are observed to drive management decision making, so being able to understand resilience or longer-term context of that engineered environment is of great value. This collection of seven papers, provides both a context for the impact and a detailed assessment of properties and mechanisms for change to engineered properties driven by these factors.
The first two papers in this issue address specific scenarios where the engineering properties of materials influence the wider impact and hazard potential of both natural and artificial structures. The first is a critical assessment of aquaculture ponds Naraju and Sunil, Briefing: Intensive inland aquaculture ponds: challenges and research opportunities. This type of agriculture is rapidly expanding in Asia, with an increasing potential for wider environmental impact from pollution. The driving forces are strong economic development potential but also threaten other natural ecosystems (see Luo et al., 2022). The briefing here reviews the scenario of aqua culture and focuses on the geotechnical perspective of engineered structures but also those that are less well designed and constructed. The threat from untreated/unmanaged wastewater and contamination that spills across wider geographical zones. The need for more locally managed systems is clearly presented and hints at wider issues from climate change in particular temperature and consequences for productivity and impact of diseases (Panicz et al., 2022).
Natural processes in costal zones include the stability of slopes under ever increasing impacts from land-sea interactions in particular those induced by impacts from climate change such as increased frequency of storm events. Napoli et al. introduce this topic with the second paper Gravity-induced collapse of a soft rock cliff due to notch growth. Here they explore the impact of undermining of coastal cliffs in soft rock materials. The influence of structural components on likely failure, modelled dependence on geometrical relationships and concluding with implications for management of coastal zones and the challenges for mitigation strategies.
The next three papers in this volume relate to the behaviour of engineered surfaces under various loading scenarios which are the common across all areas of geotechnical engineering. In the first, Xu et al. study entitled Ecological flexible protection method of expansive soil slopes under rainfall evaluates a new approach to stabilising exposed soil surfaces during excavation and development activity. Soil erosion by water is a severe threat to engineered surfaces and constitutes a significant pollution threat for water bodies in close proximity. Therefore, the protection of this surface as development takes place is paramount. Techniques of greatest value are through natural revegetation, but this can take considerable time to be established. This study evaluates an approach utilising artificial materials to stabilise the surface in partnership with plant materials. The advantage over other methods being the ability to stabilise and reduce immediate impact of rainfall and water migration.
During road installation in weak and easily deformed surface environments such as karst landscape, deformation of surfaces can be unpredictable. The work by Ge et al., presented in their paper Research on the control of high-fill roadbed with tunnel slag in karst sections provides an evaluation of the impact of construction approaches in this landscape. They investigate the potential for utilising waste slag and diverse clay-gravel mixtures on the structural integrity of road surfaces. The pre-treatment of roadbed surfaces can increase the performance of these systems and achieve reliable load bearing. The construction of roads in these landscapes is poorly developed and safety case not extensively researched (Denysyk et al., 2021) and Ge et al., provide important direction for future construction practice.
Further evaluation of construction processes in difficult engineering scenarios is addressed in the third paper of this trio. The deformation characteristics of lightweight materials used in road construction were studied and the paper Dynamic deformation characteristics of lightweight soil based on Davidenkov model we are presented with an evaluation of the geotechnical properties of soil materials using dynamic shear tests. The effect of mixtures and additives e.g. cement, particle size were investigated. The validation of the modelling approach demonstrated the potential to predict impacts of changing stress conditions from traffic use of prepared surfaces. The implications not just for transportation applications but also under different loading scenarios such as in landslides and earthquakes.
When studying migration of pollutants in soil systems the flow is critically influenced by the connectivity of flow path. The assessment of factors controlling this process are need both form real field assessments but also in more constrained laboratory simulations. The study by Yan et al. Laboratory investigation on the longitudinal dispersivity of sand–illite mixtures has provided important observations on the influence of clay content in the control of contaminant migration. This has previously been weakly considered, and the results provide support for more detailed assessment in simple migration tests and more widely for emerging migration processes such as in carbon capture and sequestration and in the design and control of clay barriers in environmental engineering projects (Chaudhary et al., 2024).
The final paper by Trimova et al., is titled: Influence of boundary conditions on initiation of gas blowout in permeable rock. The topic is critical in a range of scenarios including those of shallow marine sediments in offshore gas and oil supply, and also in landfill sites and in the issues around carbon sequestration methods for future carbon capture schemes. This work focuses on permafrost scenarios and identifies the development of pressure zones in subsurface environments where methane hydrate deposits are affected by global warming leading to migration and catastrophic release. The study offers predictive tools for locating potential blow out points and part of the risk evaluation of future exploration in polar regions (Yakushev, 2023).
In conclusion this issue has raised a number of questions about the future performance of engineered systems in the dynamic case of climate induced pressures. A range of topic need to be further evaluated. We have to consider impact on infrastructure and surface environments form changes to infiltration rates, and pore-water pressures, stress field and liquefaction of cohesive materials. Water migration (along with other fluid phases) and the impact on swelling and shrinkage works hand in hand with the role of fine particles in undermining ground stability. It is also interesting to note the incorporation of process by products in engineered systems – roads, embankments and the opportunity to stabilise what would otherwise be poorly performing materials. If risks can be mitigated, this has considerable potential to reduce carbon footprint and move towards more sustainable practice. How we work to take the large-scale climate change scenarios to localised impacts still offer much to challenge geotechnological engineering research and this collection of papers both demonstrates the wide scale of research need and opportunity for further innovation.
To follow up on these opportunities we also need to ensure that our research collaborations are focused on core engineering and science skills. The individuals making early career decisions need to be guided through taught and research programs developed to connect broader environmental context with engineering solutions. So we look to our educational infrastructure to develop these skills so future opportunities and demands can be supported.
