Research Advances in Hydraulic Structure and Geotechnical Engineering

1. Introduction

The escalating global energy demand coupled with accelerating low-carbon transitions has intensified focus on hydro energy resources as a renewable clean energy source [1]. Hydraulic engineering construction serves as the primary means for harnessing these resources, playing a pivotal role in water regulation, flood control, and irrigation through precise management of river levels and flow regimes [2]. Concurrently, such development drives innovations in geotechnical engineering. However, hydraulic engineering faces various challenges in terms of design, construction, and operation due to complex geographical conditions. For example, under strong seismic conditions, soil liquefaction is prone to occur, leading to foundation settlement and dam slope instability, while other hydraulic structures may also suffer damage [3]. Highly efficient and accurate safety assessments must be conducted at the design stage through advanced model testing and numerical simulation studies [4,5]. The significant variation in size is a remarkable characteristic of the earth-rock dam. Therefore, developing advanced refined analysis methods is crucial [6,7,8,9,10]. Deformation, stability, and seepage control represent critical issues common to both hydraulic structures and geotechnical engineering [11,12,13]. Continuously refining quality monitoring methodologies for construction, implementing effective control measures, and employing scientific approaches to monitor quality indicators are essential [14,15]. These practices enable the precise identification of operational conditions and the timely issuance of anomaly alerts, which are paramount to ensuring the long-term operational safety of a structure [16,17].

Therefore, this Special Issue focuses on research related to hydraulic structure safety and geotechnical engineering, aiming to advance the development and regulation of water resources while providing novel approaches and methodologies for hydropower resource exploitation. This holds significant importance for enhancing the safety of hydraulic engineering projects and promoting human societal development.

Since the call for papers, twelve original research articles have been accepted for publication following rigorous peer review. These studies encompass seismic response analysis and safety evaluation of hydraulic structures, fundamental geotechnical investigations, and the application of cutting-edge numerical simulations, modern experimental techniques, and machine learning methodologies. To facilitate reader engagement with this Special Issue, we highlight key findings from the published works below.

2. Overview of Contributions to this Special Issue

In the assessment of structural safety and performance of hydraulic engineering structures, Tang et al., addressing concrete-faced rockfill dams (CFRDs) on deep overburden layers, systematically investigated the influence of computational domain size on dam acceleration response and post-earthquake deformation using seismic wave input methods. They proposed quantitative criteria for the relationship between lateral boundary length, underlying overburden depth, dam height, and overburden thickness. This offers a practical framework balancing accuracy and efficiency for determining model scope in the seismic analysis of high dams on deep overburden in strong earthquake zones. Xu et al. employed comprehensive physical landslide flume experiments to investigate unsaturated soil behavior under simulated rainfall events. Their study systematically quantified the soil–water characteristic curves (SWCC) and associated hydraulic hysteresis effects in sandy colluvium during cyclic wetting-drying phases. Results demonstrated how matrix suction variations and moisture retention dynamics directly influence shear strength reduction preceding failure. This experimental work delivers fundamental empirical evidence elucidating the pore pressure development mechanisms and progressive failure pathways characteristic of rainfall-induced landslides in partially saturated slopes. The dataset provides critical calibration benchmarks for numerical models predicting instability thresholds in vulnerable hillslopes. Focusing on rockfill dams over deep liquefiable layers, Li et al. employed the effective stress method to conduct an in-depth analysis of foundation liquefaction effects and dam dynamic response patterns under seismic action. This provides key references for the seismic safety evaluation of high dams in strong earthquake zones. Through systematic laboratory model tests, Chang et al. revealed the seepage failure mechanism of red mud tailing dams under varying water level conditions. They elucidated the intrinsic relationship between the phreatic line position, pore water pressure, and crack evolution, providing experimental evidence and theoretical support for the safe operation and seepage disaster prevention of red mud tailing dams. Based on the inversion of monitoring data and finite element simulation, Pan et al. achieved the prediction of deformation and cracking in a high core rockfill dam during the impoundment period. This demonstrates the practical value of data-driven methods for long-term safety assessment of high dams.

In fundamental research in geotechnical engineering, Yang et al. constructed a Convolutional Neural Network (CNN) model to achieve intelligent prediction of the permeability coefficient of rockfill materials, providing a new method for the rapid and non-destructive assessment of geotechnical engineering parameters. Leveraging 3D point clouds and Python algorithms, Guo et al. proposed a soil modeling and prediction method for dredging engineering areas. By integrating borehole data with geological point clouds, they achieved high-precision soil type identification and volume calculation, providing an innovative tool for the digital management of underwater earthwork projects. Josip et al. employed small-scale physical modeling to investigate an alternative method for determining the soil–water characteristic curve (SWCC) of a uniformly graded sandy soil. They constructed a 35-degree, 30 cm thick slope model equipped with soil moisture and pore water pressure sensors and subjected it to a series of controlled rainfall events with intensities ranging from 37 to 300 mm/h. By measuring the steady-state suction and moisture content under different rainfall conditions, the researchers successfully plotted data points to define both the drying and wetting branches of the SWCC, thereby capturing hydraulic hysteresis effects. The best-fit van Genuchten model parameters indicated air entry values of approximately 1.6 kPa for drying and 1.1 kPa for wetting. The results demonstrate that this physical modeling approach is not only viable for hydraulic characterization of steep SWCC sands but also a valuable tool for studying key phenomena in rainfall-induced slope stability, such as wetting front advancement and the influence of antecedent moisture conditions, despite the narrow suction range distinguishing saturated from residual states in such materials. Xu et al. conducted a rigorous comparative analysis between Osterberg-cell (O-cell) tests and conventional static load tests for deep foundations. Their research established a novel analytical framework for determining pile foundation bearing capacity conversion coefficients, grounded in the principle of equal displacement. This methodology specifically addresses the complex load-transfer mechanisms in layered soils, offering a robust, data-driven approach that significantly enhances the accuracy of predicting ultimate bearing capacities. Particularly relevant for offshore structures—where traditional testing faces prohibitive logistical and economic constraints—this technique enables more efficient and precise assessment of foundation performance under operational loads, thereby optimizing design safety margins while reducing project timelines and costs. Liu et al. systematically investigated the mechanical response of palm fiber-reinforced clay under different stress paths, revealing the weakening effect of fiber reinforcement under unloading conditions. This provides a crucial basis for soil improvement design in unloading engineering projects such as slope excavations.

In the prevention and control of engineering environmental hazards and disasters, Pablo et al. pioneered a computationally efficient multiphase flow model to address critical challenges in contaminant transport modeling. Their framework adopts a Eulerian reference system and implements an implicit central difference scheme to resolve the shear stress dynamics at oil–water interfaces with high fidelity. This formulation accurately captures the viscous drag interactions governing the migration of buoyant hydrocarbon slicks across highly irregular land–water boundaries—including wetlands, estuaries, and urban drainage systems. The model’s capability to simulate continuous, seamless contaminant propagation across disparate domains provides emergency responders with a reliable predictive tool for rapid impact assessment of terrestrial-originated oil spills threatening aquatic ecosystems, ultimately supporting optimized containment strategy deployment. The seminal work by Konrad et al. represents a significant methodological advancement. By innovatively coupling high-resolution hydraulic models with dynamic groundwater simulations, their research achieved an unprecedented watershed-scale quantification of transient water retention capacities attributable to beaver dam construction activities. This pioneering analysis rigorously demonstrates how such natural infrastructure functions as distributed storage systems during critical hydrological phases. The study’s empirical findings establish robust scientific evidence supporting the strategic implementation of nature-based solutions (NbSs) in contemporary water resource management frameworks. Specifically, it validates the hydrological efficacy of beaver-mediated processes in enhancing watershed resilience, thereby offering actionable insights for sustainable ecosystem management and climate adaptation planning where engineered and ecological approaches synergistically coexist.

3. Conclusions

This Special Issue delves into the safety of hydraulic structures and geotechnical engineering research, exploring structural response, material properties, and advanced intelligent methodologies. The research findings and approaches presented—including refined numerical modeling, parameter inversion, seepage failure, water–soil interaction, and intelligent prediction models—hold significant scholarly value. We anticipate these findings will provide researchers, engineers, and project managers with reference frameworks and actionable pathways for safety monitoring, risk assessment, and disaster prevention decision-making within hydraulic infrastructure. We look forward to continued contributions from scholars and engineering specialists in advancing theoretical innovation and technological translation within this field, collectively addressing the complex challenges confronting future engineering safety and sustainable development.