Search Results (266)

This study introduces a conceptual model for understanding the hydromechanical behavior and zonation within tailings storage facilities (TSFs) constructed using the hydraulic backfill method, which constitutes over 98% of TSFs worldwide. The model identifies four distinct zones—dike, discharge, transition, and distal—each characterized by unique physical, geotechnical, and hydraulic properties. Key findings highlight gradients in parameters which systematically vary from the dam toward the settling pond. This study observes that seven parameters such as grain size, friction angle, shear strength, dry density, permeability, shear wave velocities, and liquefaction capacity decrease in value from the dike to the lagoon. Conversely, thirteen parameters such as fine content, porosity, cohesion, plasticity, degree of saturation, volumetric and gravimetric water content, capillary height, specific and volumetric surface of tailings, suction, air and water entry value in the soil water characteristic curve increase in value from the dike to the lagoon. These trends underscore the complex behavior of tailings and their implications for stability, drainage, and environmental impact. By integrating geological, geotechnical, hydrogeological, and geophysical data, this study provides a holistic framework for TSF management, addressing both current challenges and long-term environmental considerations. Full article

The precise selection of agricultural land is essential for guaranteeing global food security and sustainable development. Additionally, agricultural land suitability (AgLS) analysis is crucial for tackling issues including resource scarcity, environmental degradation, and rising food demands. This research examines the synergies and trade-offs among the sustainable development goals (SDGs) using a hybrid geographic information system (GIS)–fuzzy analytic hierarchy process (FAHP)–geostatistical framework for AgLS analysis in Attur Taluk, India. The area was chosen for its varied agro-climatic conditions, riverine habitats, and agricultural importance. Accordingly, data from ten topographical, climatic, and soil physiochemical variables, such as slope, temperature, and soil texture, were obtained and analyzed to carry out the study. The geostatistical analysis demonstrated the spatial variability of soil parameters, providing essential insights into key factors in the study area. Based on the receiver operating characteristic curve analysis, the results showed that the FAHP method (AUC = 0.71) outperformed the equal-weighting scheme (AUC = 0.602). Moreover, suitability mapping designated 17.31% of the study area as highly suitable (S1), 41.32% as moderately suitable (S2), and 7.82% as permanently unsuitable (N2). The research identified reinforcing and conflicting correlations with SDGs, emphasizing the need for policies to address trade-offs. The findings showed 40% alignment to climate action (SDG 13) via improved resilience, 33% to clean water (SDG 6) by identifying low-salinity zones, and 50% to zero hunger (SDG 2) through sustainable food systems. Conflicts arose with SDG 13 (20%) due to reliance on rain-fed agriculture, SDG 15 (11%) from soil degradation, and SDG 2 (13%) due to inefficiencies in low-productivity zones. A sustainable action plan (SAP) can tackle these issues by promoting drought-resistant crops, nutrient management, and participatory land-use planning. This study can provide a replicable framework for integrating agriculture with global sustainability objectives worldwide. Full article

With the acceleration of urbanization, clay with significant variations in organic matter content is commonly encountered in infrastructure construction. Its unique water retention capacity is crucial for engineering safety and stability. This study uses red clay as the matrix and incorporates peat to prepare soil samples with varying organic matter content. Soil–water characteristic tests were conducted using the pressure plate method, filter paper method, and vapor equilibrium method to obtain the soil–water characteristic curves across the entire suction range. Subsequently, scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) tests were performed to analyze the mechanisms underlying the water retention characteristics. The experimental results indicate that the three different suction tests accurately reflect the soil–water characteristic curves of organic clay across the entire suction range. As the organic matter content in the soil increases, the air entry value and residual value of the soil samples exhibit a linear relationship with the organic matter content, enhancing the soil’s water retention capacity. The increase in organic matter content alters the microstructure of the clay, transforming the mineral–organic aggregates from ellipsoidal to plate-like shapes. While organic matter can influence the water retention of clay, within a certain suction range, the water retention capacity of organic clay is also related to the pore structure and the state of water within the pores. This is crucial for ensuring engineering safety and optimizing design solutions. Full article

Cohesive Oxisols are a type of soil common in the Coastal Plateau in Brazil. These soils represent a challenge for agriculture and their study is fundamental to better land use. There have been a few studies on the porous system of cohesive soils on the micrometer scale. Our study aimed to provide a detailed analysis of the pore complexity of the cohesive horizon of a Brazilian Oxisol using 3D images (volumetric data reconstructed by 2D CT slices) and to correlate these parameters with soil physical–hydric attributes. For this purpose, images with two different resolutions were analyzed from multifractal, lacunarity, and entropy analyses. Additionally, a characterization of hydraulic properties was carried out based on a soil water retention curve (SWRC). No differences were observed between the resolutions for the different physical parameters analyzed. The lacunarity analysis showed a greater homogeneity of the pore system with pores grouped in clusters. The multifractal analysis showed fractal characteristics for the cohesive horizon, suggesting a more homogeneous pore distribution. The main results obtained from the SWRC showed a low available water content due to the predominance of ultramicropores. Overall, the results show a less complex pore system, indicating the presence of pores of small sizes, affecting the water retention and conduction through the soil. Full article

Urmia Lake (UL) is the sixth-largest saltwater lake in the world; however, there is a dearth of geotechnical studies on this region. Geotechnical characteristics of a site are considered important from different engineering perspectives. In this research, the results of 255 laboratory tests and the data of 55 in situ tests were used to determine the geotechnical properties of sediment in UL. The changes of parameters in depth are presented in this study. The results indicate that compressibility, initial void ratio, water content, over-consolidated ratio (OCR), and sensitivity have larger values near the lake bed. Moreover, increasing the sediment depth leads to significant reductions in these values. According to the sediment strength analysis through the vane shear and standard penetration tests and the unit weight of sediments, there is an increasing trend caused by the increased depths of layers. Diverse applied correlations are proposed and can be used as preliminary estimates in similar types of sediments in engineering projects as well as scientific studies. Furthermore, undrained shear strength and compression index trends in depth and the Su/σ’_v Curve against OCR are compared with the literature, and the results reveal similar trends in similar sediments. The main minerals identified in these sediments include calcite, dolomite, quartz, calcium chloride, and halite. The salinity of the lake water is caused by the presence of calcium chloride and halite minerals. The Cao factor observed in chemical compounds can have a significant impact on the cohesion of the soil particles. This research provides comprehensive information on the geotechnical characteristics of UL. Moreover, the results of this study show that UL Sediments are soft and sensitive, especially in shallow depths, and they contain a significant amount of organic content; therefore, it is recommended to use suitable improvement methods in future geotechnical and structural designs. This study and similar surveys can help prepare the groundwork for designing safer marine structures. Full article

As tunnel excavation technology matures and the demand for transportation infrastructure continues to grow, several high-temperature tunnels have successively emerged in high geothermal areas. The construction of tunnels in high-temperature regions is gradually becoming a new challenge encountered in the engineering field. This study aims to conduct a stability analysis of tunnel face excavation under different temperatures. In addition, soil is often considered to be unsaturated. A framework for assessing the stability of tunnel faces in unsaturated soils under fluctuating temperature conditions is proposed, with an analytical approach. The theoretical basis of this framework is established on the influence of temperature on the shear strength of unsaturated soil. The matric suction of unsaturated soil changes with temperature, thereby inducing variations in shear strength. The temperature-induced variation in apparent cohesion is quantified utilizing a temperature-sensitive effective stress model coupled with a soil–water characteristic curve. These models are subsequently incorporated into the stability assessment of tunnel faces in unsaturated soils under steady-state flow conditions. A three-dimensional logarithmic spiral model is utilized to ascertain the unsupported pressure on tunnel faces, with the safety factor (FS) being calculated through an iterative methodology. Subsequently, a comprehensive suite of parametric studies is undertaken to explore the influence of temperature on tunnel face stability under unsaturated seepage conditions, offering valuable insights for practical engineering endeavors. Full article

The interaction between moisture content and soil suction is commonly represented by a soil–water characteristic curve (SWCC). The direct measurement of water content can be easily achieved, but it usually requires a destructive method where the soil sample needs to be oven-dried. Hence, indirect measurement is commonly employed for monitoring purposes. The limitation of this approach is the variability in water content at the wilting point, particularly for plants in different types of soil. While the moisture content at the wilting point varies greatly, suction at the wilting point is typically around 1500 kPa despite varying slightly depending on the type of plant. However, suction measurement using a normal tensiometer is limited to 100 kPa due to cavitation. Hence, it is not sufficient to cover up to the wilting point. The focus of this paper is the establishment of a polymer-based tensiometer utilizing a 15 bar ceramic disc for the measurement of high suction. The suitability of the polymer-based tensiometer in measuring the soil suction of vegetative soil is conducted by performing a soil–water characteristic curve test on vegetative soil. The SWCC produced from the polymer-based tensiometer is verified using SWCC produced from a centrifuge test. The results show that the SWCCs from both polymer-based tensiometer and centrifuge tests are comparable. Hence, suction measurement using a polymer-based tensiometer is deemed reliable. This advancement in suction measurement technology is crucial for improving irrigation practices, optimizing water use, and enhancing agricultural productivity, which in turn contributes to environmental sustainability by minimizing water waste and ensuring efficient soil management. Full article

Soil hydraulic properties are mainly governed by the soil’s heterogeneity, anisotropy, and discontinuous structural characteristics, primarily when connected soil macropores characterize the structures. Therefore, researchers must document reliable hydrological models to elucidate how the soil medium affects the movement of soil water. This study, utilizing a field-scale staining tracer test, distinguishes between matrix flow and preferential flow areas in the seepage field of Xi’an loess. The Xi’an loess’s soil water characteristic curve (SWCC) was explored through field investigations and laboratory analyses. A dual-permeability model that couples matrix and macropore flow was developed using the Hydrus-2D model, enabling simulations of water migration under varying initial soil water content, rainfall intensity, and crack width. The results showed that (1) The SWCC of macropores in the preferential flow area exhibits a bimodal distribution, and the Fredlund & Xing model is applied for sectional fitting to obtain the corresponding soil water characteristic parameters. (2) Initial soil water content and rainfall intensity significantly influence water distribution, while crack width has a relatively minor effect. (3) The cumulative flux under the preferential flow is significantly higher than in the matrix area, and the wetting front depth increases with higher initial water content and rainfall intensity. This study reveals the key characteristics of preferential flow and moisture migration in the matrix zone and their influencing factors in loess. It constructs a two-domain infiltration model by integrating loess’s diverse structural characteristics and pore morphology. This model provides a theoretical basis and technical support for simulating preferential flow and studying the moisture dynamics of loess profiles. Full article

This work aims to improve the accuracy of traditional models for analyzing the hydraulic properties of unsaturated soil by integrating digital imaging measurement with deep learning techniques. The work first reviews current research on the basic characteristics of unsaturated soil and the applications of deep learning in this field. Next, it examines the impact of soil specimens’ physical properties on their hydraulic properties. This includes acquiring hydraulic parameters and the soil-water characteristic curve through full-surface digital imaging measurements. Finally, a soil hydraulic property model based on the backpropagation neural network (BPNN) is implemented, trained, and validated. Results indicate that the model’s predicted soil-water characteristic curve aligns closely with the experimental findings from previous studies. Moreover, the proposed BPNN-based unsaturated soil hydraulic property model uses the Levenberg–Marquardt algorithm, which reduces computational time and noise compared to alternative algorithms. Meanwhile, analysis of the model parameters suggests that ten neurons in the hidden layer provide optimal performance. By incorporating correlations between physical parameters, such as soil particle size and soil hydraulic properties, the model demonstrates lower error rates compared to other literature models. Overall, this BPNN model effectively represents the relationship between soil’s physical and hydraulic parameters, streamlining traditional soil correlation coefficient estimation. Full article

Benggangs are a unique type of soil erosion commonly found in southern China, with the gully wall being the most dynamic component of the Benggang system and is crucial for assessing its overall progression. The unsaturated shear strength of soil in Benggang areas is a key factor influencing the stability of the gully wall. However, quantitative analyses of the unsaturated shear strength in the gully walls of Benggangs remain limited. In this study, the soil–water characteristic curves (SWCC) and shear strengths of undisturbed soil samples from four different soil layers in the gully wall of Benggang were measured using a pressure membrane meter and a quadruple direct shear apparatus. The results revealed that the water holding capacity of the soil decreased gradually with increasing matrix suction, and the order of the water holding capacity was the sandy soil layer > transition layer > laterite layer > clastic layer. With an increasing soil water content (SWC), the shear strength, cohesion (c), and internal friction angle (φ) of the four soil layers decreased significantly, and the φ showed a power function decreasing curve (p < 0.05), whereas c in the laterite layer and transition layer exhibited a power function decreasing curve (p < 0.01). The c of the sandy soil layer and clastic layer decreased linearly and logarithmically (p < 0.01) with increasing SWC, respectively. The unsaturated shear strength model for the four soil layers was developed based on the Vanapalli model. The root mean square error (RMSE) of the simulated and measured values was less than 29.349, while the Nash–Sutcliffe efficiency (NSE) and R² values were greater than 0.638 and 0.788, respectively. The model can be used to analyze and predict the unsaturated shear strength in different layers of Benggang gully walls, providing a theoretical foundation for studying the erosion mechanisms of Benggangs. Full article

Fragipans are dense subsurface soil layers that severely restrict root penetration and water movement. The presence of shallow fragipan horizons limits row crop production. We hypothesized that the roots of cover crop might improve soil physiochemical properties and biological activity, facilitating drainage and increasing effective soil depth for greater long-term soil water storage. To evaluate annual ryegrass as one component of a cover crop (CC) mix for promoting the characteristics and distribution of soil water, on-farm studies were conducted at Marion and Springerton in southern Illinois, USA. Soil samples were collected at 15 cm increments to 60 cm (Marion) and 90 cm (Springerton) depths during the fall of 2022. Both sites had low total soil carbon and nitrogen contents and acidic soil pH (≤6.4). A soil water retention curve was fitted using the van Genuchten equation. At Springerton, the CC treatment increased saturated (thetaS) and residual (thetaR) soil water contents above those of the no cover crop (NCC) at the 60–75 cm and 75–90 cm depths. Changes in volumetric soil water content were measured using a multi-depth soil water sensor for the Springerton site during late July to early August of the soybean growing phase of 2022; NCC had higher soil water than CC within the 0–15 cm depth, but CC had higher soil water than NCC at the 30–45 cm depth. These findings indicate that cover crop mix has the potential to improve soil water movement for soils with restrictive subsoil horizon, possibly through reducing the soil hydraulic gradient between the surface and restrictive subsurface soil layers. Full article

During coastal reclamation processes, land use conversion from natural coastal saline/sodic soils to agricultural land changes the soil’s physicochemical properties. However, the impact of soil structure evolution on soil hydraulic properties (SHPs, e.g., hydraulic conductivity and soil water retention curves) during long-term reclamation has rarely been reported. In this study, we aimed to evaluate the effect of reclamation duration and land use types on the soil aggregate stability and SHPs of coastal saline/sodic soils and incorporate the aggregate structures into the SHPs. In this study, a total of 90 soil samples from various reclaimed years (2007, 1960, and 1940) and land use patterns (cropland, grassland, forestland, and wasteland) were taken to analyze the quantitative effects of soil saline/sodic characteristics and the aggregate structure on SHPs through pedotransfer functions (PTFs). We found that soil macroaggregate contents in the old reclaimed areas (reclaimed in 1940 and 1960) were significantly larger than those in the new reclamation area (reclaimed in 2007). The soil saturated hydraulic conductivity (K_s) of forestland was larger than that of grassland in each reclamation year. Soil structure contributed to 22.13%, 24.52%, and 23.93% of the total variation in K_s and soil water retention parameters (α and n). The PTFs established in our study were as follows: log(K_s) = 0.524 − 0.177 × ${\mathrm{Y}}_{k_3}$ − 0.093 × ${\mathrm{Y}}_{k_1}$ + 0.135 × ${\mathrm{Y}}_{k_4}$ − 0.054 × ${\mathrm{Y}}_{k_2}$, 1/α = 477.244 − 91.732 × ${\mathrm{Y}}_{{\alpha }_2}$ − 81.283 × ${\mathrm{Y}}_{{\alpha }_4}$ + 38.106 × ${\mathrm{Y}}_{{\alpha }_3}$, and n = 1.679 − 0.086 × ${\mathrm{Y}}_{n_2}$ + 0.045 × ${\mathrm{Y}}_{n_1}$ − 0.042 × ${\mathrm{Y}}_{n_3}\left(\mathrm{Y}\mathrm{a}\mathrm{r}\mathrm{e}\mathrm{p}\mathrm{r}\mathrm{i}\mathrm{n}\mathrm{c}\mathrm{i}\mathrm{p}\mathrm{a}\mathrm{l}\mathrm{c}\mathrm{o}\mathrm{m}\mathrm{p}\mathrm{o}\mathrm{n}\mathrm{e}\mathrm{n}\mathrm{t}\mathrm{s}\right)$. The mean relative errors of the prediction models for log(K_s), 1/α, and n were 79.30%, 36.1%, and 9.89%, respectively. Our findings quantify the vital roles of the aggregate structure on the SHPs of coastal saline/sodic soils, which will help us understand related hydrological processes. Full article

Splitting grouting is a highly effective technique for reinforcing tunnels and underground structures, ensuring their operational stability and facilitating long-term maintenance. It has been widely adopted in the prevention and remediation of geological hazards. However, the theoretical research on the diffusion mechanisms of split grouting lags behind its practical applications. This study addresses several key scientific challenges in understanding the diffusion behavior of split grouting. By integrating experimental design, numerical simulations, and theoretical analysis, we conduct a systematic investigation into the diffusion process and vein morphology of split grouting in both homogeneous and heterogeneous formations. We first employed a self-developed two-dimensional grouting test system to perform diffusion experiments on cohesive strata, focusing on the influence of various factors such as grout density, water/cement ratio, soil consistency, and fracture characteristics. The results provide insights into the diffusion patterns, morphology, soil pressure distribution, and surface uplift behavior of the grout veins. Subsequently, a numerical simulation program, developed in-house, based on the finite element method (FEM) and the volume of fluid (VOF) approach, was employed to model the entire process of fracturing grouting within clay strata. The experimental and numerical results indicate that grout vein diffusion in layered soil follows a Y-shaped pattern with an inclined deflection. In uniform strata, the surface uplift curve displays both symmetrical and asymmetrical “convex” elevations, while in heterogeneous soft and hard strata, the uplift is characterized by distinct “convex” deformations. Finally, based on these findings and the principles of contact mechanics, we analyze the underlying mechanisms. The results suggest that weak contact zones undergo tensile cracking and horizontal deflection prior to the formation of grout veins. Additionally, local stress rotations in the soil can induce tilting and deflection. The theoretical insights derived from this study provide valuable guidance for practical engineering applications. Full article

Weathering processes of rocks lead to the formation of residual soil layers, which are typically characterized by a deep groundwater table and a thick unsaturated zone. Hence, the calculation of a slope’s safety factor under the influences of climatic circumstances is a function of unsaturated characteristics, such as the soil–water characteristic curve (SWCC). To determine the SWCC, the volume of the soil specimen must be determined in order to compute the void ratio and degree of saturation. The drying processes of the soil specimen led to uneven soil volume change during laboratory SWCC testing, demanding the development of a soil shrinkage curve. Several methods for measuring soil volume change have been developed over the years. However, there are significant limitations, and it is rarely used due to the difficulty linked to accurately measuring the soil volume during drying processes. In this study, a revised scanning approach is developed to evaluate residual soil volume change utilizing 3D scanning technology. The proposed method is applied in a case study on residual soil from the Old Alluvium in Singapore. The laboratory data and analysis results suggested that 3D scanning technology should be required to provide a correct estimation of the air-entry value of soil. Full article

Modeling peatland hydraulic processes in cold regions requires defining near-surface hydraulic parameters. The current study aims to determine the soil freezing and water characteristic curve parameters for organic soils from peatland-dominated permafrost mires. The three research objectives are as follows: (i) Setting up an in situ soil freezing characteristic curve experiment by installing sensors for measuring volumetric water content and temperature in Storflaket mire, Abisko region, Sweden; (ii) Conducting laboratory evaporation experiments and inverse numerical modeling to determine soil water characteristic curve parameters and comparing three soil water characteristic curve models to the laboratory data; (iii) Deriving a relationship between soil freezing and water characteristic curves and optimizing this equation with sensor data from (i). A long-lasting in situ volumetric water content station has been successfully set up in sub-Arctic Sweden. The soil water characteristic curve experiments showed that bimodality also exists for the investigated peat soils. The optimization results of the bimodal relationship showed excellent agreement with the soil freezing cycle measurements. To the best of our knowledge, this is one of the first studies to establish and test bimodality for frozen peat soils. The estimated hydraulic parameters could be used to better simulate permafrost dynamics in peat soils. Full article