As a newly elected member of the Early Career Researchers Board (ECRB) for Environmental Geotechnics, I am honored to contribute to this issue. I would like to express my sincere gratitude for the opportunity to share my thoughts on environmental geotechnics. My research primarily focuses on contaminant behaviour in porous media, which aligns directly with the central theme of this journal. This position allows me to collaborate with emerging researchers, bringing fresh perspectives and innovative methodologies into the conversation, thus contributing to the growth of our field. I began my academic journey during doctoral studies, which has evolved from field-based studies on contaminant behaviour in soils and gas transport through geosynthetic clay liners to molecular dynamics simulations of multicomponent behaviour in soils. I am particularly excited to continue this research within the context of environmental geotechnics, especially as the field continues to advance in response to emerging global challenges.
The intersection of geotechnical engineering, sustainability, and environmental science has seen significant developments in recent years. The drive toward sustainable development has become a defining challenge for environmental geotechnics, particularly in addressing the complex interactions between resource extraction, waste management, and engineering performance. The contributions in this issue span a variety of timely and relevant topics, from resource sustainability and dynamic material behaviour to waste utilisation, gas migration, soil-water interactions, and predictive modelling for geosynthetic performance. Together, these papers provide a comprehensive overview of the emerging challenges and innovative solutions that are shaping the future of geotechnical engineering with sustainability at its core.
The first paper entitled ‘Sustainability challenges of clean-energy critical minerals: copper and rare earths’ investigates the environmental and operational challenges arising from the escalating global demand for copper and rare earth elements, driven by the transition to renewable energy systems. As clean energy technologies rely heavily on these minerals, the surge in demand has intensified pressures on mining sectors to adopt sustainable practices, address resource scarcity, and mitigate supply chain vulnerabilities. Mining and mineral processing activities generate vast quantities of waste, representing one of the most persistent environmental concerns globally (Bian et al., 2012; Macklin et al., 2023). This paper critically examines the environmental challenges of mineral mining and the sustainable utilisation of mineral waste and tailings, as well as the current state of and future trends in processes and recycling. The proposed solutions involve improving mining efficiency, reducing waste, optimising water management, and enhancing recycling techniques for end-of-life products. A significant contribution of this research to environmental geotechnics lies in the potential of repurposing mine tailings for engineered applications, such as sustainable construction materials, which helps mitigate ecological risks while reducing reliance on natural resources.
Extending the discussion on innovative material applications, the second paper entitled ‘Dynamic properties of high-density polyethylene–sand by large-scale direct shear experiments’ explores the dynamic properties of sand reinforced with high-density polyethylene (HDPE) waste. Through large-scale cyclic shear testing, the study evaluates the influence of HDPE on damping and shear stiffness. They found that the damping ratio rose and the shear stiffness decreased compared with those of pure sand, demonstrating its potential for energy dissipation applications in geotechnical engineering. The findings suggest that while HDPE inclusion enhances damping capacity, its effect on shear stiffness necessitates careful consideration in engineering designs, highlighting the trade-offs involved in sustainable material use.
Building upon the theme of sustainable material use, the third paper ‘Damage constitutive model of fly ash–cementitious iron tailings powder under small strain’ delves into the mechanical and damage behaviour of iron tailings powder stabilized with fly ash and cement. The study finds that when 5%–10% fly ash content was used as a substitute for 10% cement, the unconfined compressive strength and small-strain modulus of cement–fly ash–ITP increased with curing age. This research underscores the potential of incorporating industrial by-products into geotechnical applications, thereby addressing both waste accumulation and engineering performance concerns. By developing a damage constitutive model, the study provides valuable insights into the strength evolution and microstructural characteristics of these materials under varying curing conditions, further supporting the case for sustainable construction practices.
Shifting focus to subsurface processes, the fourth paper ‘Experimental investigation of gas migration behaviour in unsaturated sand-clay mixtures’ investigates gas migration behaviour in unsaturated sand–clay mixtures. As the behaviour of gas in natural and engineered barriers will strongly affect the sustainable and safe implementation of engineering activities, this study presents an empirical framework for predicting gas flow behaviour through comprehensive experimental assessment of permeability variations under different moisture contents and sand-clay ratios. They indicated that when the gas pressure is above 300 kPa, the gas permeability remains constant with an increasing gas pressure. In this case, the gas permeability of soil is related only to the shear strength and stress state of the soil and has nothing to do with the sand-clay ratio or moisture content. The identification of permeability transition stages offers a refined understanding of gas transport mechanisms in unsaturated soil systems, contributing to improved geotechnical designs.
Continuing with subsurface interactions, the fifth paper ‘Temperature-dependent relationship between soil water content and electrical conductivity’ addresses the relationship between soil water content and electrical conductivity under varying temperature conditions. By evaluating multiple predictive models, the study demonstrates the strong dependency of electrical conductivity on temperature variations, which has implications for in situ monitoring of soil moisture in extreme environments. These insights contribute to improving the reliability of electrical conductivity as an indirect measure of soil water content in geotechnical applications, reinforcing the importance of accurate and adaptive monitoring techniques.
Finally, advancing into predictive modelling, the sixth paper ‘Prediction of hydraulic conductivity of sodium bentonite GCLs by machine learning approaches’ employs machine learning techniques to predict the hydraulic conductivity of sodium bentonite-based geosynthetic clay liners (GCLs) when exposed to saline solutions or leachates. By leveraging various predictive algorithms, including support vector machines and artificial neural networks, the study enhances the understanding of GCL performance under complex environmental conditions, offering an innovative approach to handling complex environmental interactions. The integration of data-driven methodologies in geotechnical engineering highlights the growing role of artificial intelligence in optimising material selection and performance assessment, bridging traditional experimental methods with modern computational advancements.
This issue is notable for its inclusion of both traditional geotechnical engineering research and emerging methodologies. As we continue to advance more efficient, resilient, and environmentally friendly geotechnical solutions, the integration of experimental research, innovative materials, and new computational techniques will remain essential. The application of computational techniques such as molecular dynamics simulations will provide valuable molecular-scale insights into traditional geotechnical challenges, while machine learning and artificial neural networks offer promising avenues for predicting and optimising material behaviour in complex environmental settings. Environmental Geotechnics will continue advancing interdisciplinary research, embracing innovative computational methods, focusing on sustainability and climate adaptation, and exploring emerging technologies. We invite contributions that bridge fundamental science, engineering practise, and policy-relevant insights. Together, we can forge a resilient and sustainable future for geotechnical systems in an era of unprecedented environmental change.
