This issue of Geotechnical Engineering features nine papers that highlight our discipline’s growing focus on accuracy, resilience and innovation. The articles encompass a wide range of topics, including ground improvement, tunnelling performance, geo-structural monitoring, slope stability and energy piles, offering practical and theoretical advances in addressing modern infrastructure challenges.
A significant theme in this issue is ground improvement techniques and grouting methods. Mahdavi and Lehane (2025) introduce an efficient post-installation grouting method for helical piles in sandy soils. This new technique utilises a minimal grout volume, thereby reducing environmental impact. Validated through field trials and exhumation studies in Western Australia, it can double the axial resistance of piles. In a complementary contribution, Zhang et al. (2025) propose a novel multi-resistivity geophysical method that integrates surface and borehole electrical resistivity tomography with principal component analysis (PCA) to evaluate grouting effectiveness. Their field-validated approach enables high-resolution three-dimensional (3D) imaging of grouted zones, improving post-injection quality assurance and guiding future grouting strategies. Wang et al. (2025) examine the explosive replacement method (ERM) to reinforce silty soils with rockfill. Through chamber experiments, they demonstrate how explosive energy affects settlement and shear strength, and provide a practical formula for settlement prediction.
Excavation and tunnelling performance are examined in the context of increasingly variable and challenging subsurface environments. Shirlaw et al. (2025) analyse the performance of a slurry tunnel boring machine (TBM) in weathered Kowloon granite. Their findings highlight the impact of rapidly changing rock strength on TBM thrust and torque, and they argue for the use of automated control systems to optimise disc cutter forces under complex conditions.
Accurate structural monitoring in urban excavations is crucial in the construction industry. Kwang and Chen (2025) tackle the challenge of interpreting axial forces in temporary props by developing a two-step signal processing method. Using the fast Fourier transform and Butterworth filtering, they effectively isolate excavation-induced forces from thermal effects and construction noise, thereby enhancing the reliability of the data used in design, validation and back-analysis.
Advancements in geotechnical modelling and risk analysis are discussed in this issue. Zhao and Thusyanthan (2025) combine finite-element and probabilistic methods to assess rainfall-induced slope instability, considering spatial variability in soil properties. Their model, tested on an embankment in the UK, introduces a 5th percentile factor of safety (FoS) of 1.1, providing new guidance for resilient slope design under changing climatic conditions. Similarly, Chen et al. (2025) propose a theoretical model for lateral soil arching behind flexible retaining walls. By identifying three stress zones and validating predictions through physical tests, they offer improved tools for analysing stress distributions in deep excavations.
In the field of energy geotechnics, Zhuang et al. (2025) examine the thermo-mechanical behaviour of energy piles subjected to non-uniform ground temperature distributions. Their 3D finite-element model, calibrated with field data, shows how simplifying assumptions – such as uniform initial temperature – can considerably misrepresent heat exchange efficiency, axial stress and displacement. These results emphasise the importance of more realistic thermal modelling in energy foundation design.
This issue concludes with the review of the XVIII European Conference on Soil Mechanics and Geotechnical Engineering (ECSMGE 2024) by Sêco e Pinto et al. (2025). With participation from over 1300 delegates and the presentation of 702 papers, the event emphasised the importance of international collaboration in advancing geotechnical knowledge and practice.
Overall, the papers in this issue demonstrate how data-driven methods, tested innovations and improved theoretical frameworks are transforming geotechnical engineering. These contributions address urgent infrastructure needs while supporting long-term goals of safety, efficiency and sustainability. We thank the authors for their efforts and appreciate the dedication of the reviewers and editorial team. We hope this issue inspires further research and continuous progress in the field.
