Search Results (32)

The South China region is characterized by diverse landforms and significant stratification of geological materials. The rock and soil layers in this area have obvious layering characteristics. The stability of layered slopes is a critical issue in the safe mining of southern ion-type rare earth ores. This study investigates the morphological changes, pore water pressure, and moisture content variation of layered ion-type rare earth ore slopes under the combined effects of rainfall and liquid infiltration through indoor model tests. A numerical simulation was conducted to analyze the variations in pore water pressure, moisture content, slope displacement, and safety factor under different working conditions. As rainfall intensity increases, the interface between soil layers in sandy–silty clay slopes is more likely to form a saturated water retention zone, causing rapid pore water pressure buildup and a significant reduction in shear strength. For the silty–sand clay slopes, the low permeability of the upper silty clay layer limits the infiltration rate of water, resulting in significant interlayer water retention effects, which induce softening and an increased instability risk. The higher the initial moisture content, the longer the infiltration time, which reduces the matrix suction of the soil and significantly weakens the shear strength of the slope. When the initial moisture content and rainfall intensity are the same, the safety factor of the silty–sand clay slope is higher than that of the sandy–silty clay slope. When rainfall intensity increases from 10 mm/h to 30 mm/h, the safety factor of the sandy–silty clay slope decreases from 1.30 to 1.15, indicating that the slope is approaching a critical instability state. Full article

This study evaluated the desertification vulnerability of an Anatolian black pine forest in Türkiye using the Environmental Sensitivity Area Index (ESAI). Desertification Risk (DR) and ESAI values were calculated for 90 sampling plots, incorporating key indicators such as vegetation cover, soil depth, rock fragment presence, soil texture, slope gradient, parent material, mean annual precipitation, aridity index, land use intensity, and policy enforcement. These indicators were processed through the Desertification Indicator System for Mediterranean Europe (DIS4ME). Spatial patterns of DR and ESAI were analysed using semivariograms and Kriging-interpolated maps. The mean DR (4.850; range = 2.310–8.090) and ESAI (1.46; range = 1.390–1.580) values indicated significant vulnerability to desertification. DR showed moderate spatial dependence, while ESAI exhibited strong spatial dependence. Ordinary kriging maps revealed critical desertification hotspots within the forest. ESAI values varied with soil organic matter (SOM) content, which was moderately and significantly correlated with ESAI (n = 90, r = −0.58, p < 0.01). These findings provide actionable insights for sustainable land management. Interventions such as improving SOM content through afforestation, enhancing soil conservation practices, and promoting sustainable water use are critical to mitigating desertification and fostering ecosystem resilience. This study identifies high-risk areas and demonstrates how DR and ESAI can guide targeted strategies to restore degraded lands and ensure forest sustainability. This aligns with SDG 15 (Life on Land), which emphasizes the need to combat desertification, restore degraded ecosystems, and promote the sustainable management of forests. Integrating ESAI into regional policy planning highlights its potential as a practical tool for achieving long-term environmental and socioeconomic sustainability in vulnerable forest ecosystems like those in Türkiye. Full article

This paper combines empirical observations, kinematic analysis, and numerical simulation to investigate slope failure susceptibility, with practical implications for regional infrastructure projects. Six slopes along the R37 road were analyzed to assess the impact of strata orientation and water presence on slope stability. The results indicate that various factors interact to destabilize the mechanical integrity of both rock and soil materials. Dry slopes were found to be less vulnerable to failure, although geological conditions remained influential. Numerical modeling using FLACSlope (version 8.1) revealed that the factor of safety (FoS) decreases as the water presence increases, highlighting the critical need for effective drainage solutions. Kinematic analysis, incorporating DIPS modeling and toppling charts, identified toppling as the most likely failure mode, with a 90% susceptibility rate, followed by planar and wedge failures at 6% and less than 5%, respectively. These findings are validated by the observed slope conditions and empirical data. Planar failures were often remnants of both sliding and toppling failures. Given the significant risk posed to road infrastructure, particularly where FoS hovers just above the stability threshold, this study emphasizes the importance of proactive, long-term slope monitoring and early mitigation strategies to prevent catastrophic failures. The results can guide infrastructure design and maintenance, ensuring safer and more resilient roadways in regions prone to slope instability. Nonetheless, the use of sophisticated slope stability modeling techniques is recommended for a thorough understanding of the mechanical dynamics of the slope material, and for catering to the shortfalls of the techniques applied in this paper. Full article

Traditional model tests for soil and rock materials face challenges in observing the slurry diffusion within the soil mass, hindering the understanding of the relationship between grouting-induced ground deformation and grout diffusion. This study conducts grouting diffusion model tests using a self-developed experimental setup on both ordinary and transparent sand. We investigate cement slurry diffusion patterns, distribution characteristics, and temporal variations in ground uplift displacement during the grouting process. By leveraging a visualization grouting model and non-intrusive displacement measurements, we directly observe and verify the changes in cement slurry diffusion and ground displacement in transparent sand. The results indicate the following: during non-steady grouting in sand, slurry diffusion progresses from low-pressure infiltration to medium-pressure compaction, culminating in high-pressure fracturing; ground uplift displacement curves exhibit a consistent “step-like” increase with grouting time, featuring accelerated growth after each step; and visualization tests reveal a strong correlation between grouting pressure, slurry diffusion, and corresponding uplift displacement. Distinct features in the grouting pressure plot align with the acceleration phases of the displacement; at a water–cement ratio (w/c) of 0.8, the stratum’s vertical deformation shows a symmetric “higher in the middle, lower on the sides” distribution. As the burial depth decreases, the stratum’s uplift displacement tends to flatten horizontally, especially at w/c = 0.8 and 1.2. Full article

Since 2013, 34 surveys of surface and ground waters within and outside the former Hg-mine of Abbadia San Salvatore (Italy), which is currently under remediation, were performed for determining Hg, As, Sb, and main and minor solutes. The water quality is rather poor since most waters show relatively high Hg concentrations (up to 695 µg/L). Differently, As and Sb only overcome the Italian law thresholds in a few sites. A high geochemical variability was observed for most groundwaters without any clear relationship between wet and dry periods. The main source of chalcophile elements is likely related to: (i) the interaction between meteoric waters and soils contaminated by the previous production of mercury; or (ii) the interaction between meteoric waters and the anthropic filling material of a former paleo-valley near the furnaces edifices. While the remediation is expected to be concluded in 2025, the aquifer contamination still remains a problem. Our investigation, including geochemical/hydrogeological modeling, is prodromal to future activities aimed at reducing the Hg content. Currently, the construction of a hydraulic barrier is apparently the most suitable solution to minimize the interaction processes between water–rock and man-made material, which are responsible for the 10-year concentration variability. Full article

Most recent tunnel designs rely on more thorough analyses of the intricate rock interactions. The three principal techniques for excavating rock tunneling are drill-and-blast for complete or partial cross-sections, TBM only for circular cross-sections with full faces, and road header for small portions. Tunnel-boring machines (TBM) are being utilized to excavate an increasing number of tunnels. Newer studies have demonstrated that subterranean structures such as tunnels produce a variety of consequences during and after ground shaking, challenging the long-held belief that they are among the most earthquake-resistant structures. Consequently, engineering assessment has become crucial for these unique structures from both the geotechnical and structural engineering standpoints. The designer should evaluate the underground structure’s safety to ensure it can sustain various applied loads, considering both seismic loads and temporary and permanent static loads. This paper investigates how adding elastic, soft material between a circular tunnel and the surrounding rock affects seismic response. To conduct the study, Midas/GTS-NX was used to model the TBM tunnel and the nearby rock using the finite element (F.E.) method to simulate the soil–tunnel interactions. A time–history analysis of the El Centro (1940) earthquake was used to calculated the stresses accumulated in the tunnels during seismic episodes. Peak ground accelerations of 0.10–0.30 g, relative to the tunnel axis, were used for excitation. The analysis utilized a time step of 0.02 s, and the duration of the seismic event was set at 10 s. Numerical models were developed to represent tunnels passing through rock, with the traditional grout pea gravel vs. isolation layer. A parametric study determined how isolation material characteristics like shear modulus, Poisson’s ratio, and unit weight affect tunnel-induced stresses. In the meantime, this paper details the effects of various seismic isolation materials, such as geofoam, foam concrete, and silicon-based isolation material, to improve protection against seismic shaking. The analysis’s findings are discussed, and how seismic isolation affects these important structures’ performance and safety requirements is explained. Full article

Sedimentary phosphate extraction in open-pit operations generates large volumes of waste rock (WR), which are mainly overburdens and interburdens. Traditionally, the WR is mixed and stored on the surface in waste rock piles (WRPs). This paper presents a case study of the Benguerir mine site in Morocco. It investigates the potential valorization of each WR lithology based on the geological and geomechanical properties to reduce their environmental footprint and create added value to “waste.” The WR samples (soils and rocks) were collected from drill cores and mining trenches in the Benguerir mine. The geological characterization results using petrographic descriptions indicate the presence of nine phosphate layers and, in addition to the overburdens, eight interburdens. Four types of WR are identified: carbonate, siliceous, marly clay, and phosphate. The geomechanical characterization of soil-like samples showed an average plasticity index (PI) of 50% according to the methylene blue value (MBV) of 7.1, classifying them in the A3–A4 categories as plastic and clayey marl soils. The hard rock samples have excellent mechanical properties in terms of their uniaxial compressive strength (UCS), Los Angeles abrasion value (LA), and micro-Deval value (MD). The average compressive strength is 104 MPa for the flint, 35 MPa for the phosphate flint, 32 MPa for the silexite, 26 MPa for the limestone, 11 MPa for the indurated phosphate, and 8 MPa for the marly limestone. Based on the obtained results, these WRs can be considered as an excellent alternative secondary raw material for use in civil engineering applications, ceramics, and cement industries. Full article

Microbially induced calcium carbonate precipitation (MICP) is an innovative biocementation technique that facilitates the formation of calcium carbonate within a pore network. Initially gaining prominence in the field of geotechnical engineering, MICP has attracted significant attention since its inception (the last three decades) and expanded its reach across various engineering disciplines. Examples include rock mechanics, geology and the oil and gas industry fields through the generation of rock-like specimens, and plugging of fractures, in civil and architectural engineering and material science for concrete repair, protection, and for self-healing of building materials, and in environmental engineering for the study of biomimetic materials. In response to this burgeoning interest, the current paper aims to present a comprehensive review of the main biochemical mechanisms underlying MICP (bacterial ureolytic activity, reactions duration and settling times, and chemical solution properties), their direct relevance to altering hydraulic and mechanical properties, both at the microscale and macroscale responses, and the precipitation mechanisms, particularly in relation to water resources and hydrology applications. Four main categories of relevant applications are identified, namely, the groundwater and soil remediation, the applications related to the generation of a low hydraulic conductivity barrier, those related to gaining cohesion, and the applications related to fluid flow studies in artificially generated porous media. Moreover, this comprehensive review not only aims to identify the existing applications of MICP within hydrological fields but also strives to propose novel and promising applications that can further expand its utility in this domain. Along with the investigation of the potential of MICP to revolutionize water resources and hydrology, it is imperative to delve deeper into its environmental implications to ensure sustainable and ecologically responsible implementation. Full article

In dykes and dam projects, the microscopic fluid-solid coupling effect from the interaction between soil skeleton and pore water during an earthquake is crucial to consider, as it can lead to dam safety problems. To control seepage in medium- and small-sized dams, polymer antiseepage walls have emerged as effective measures. In recent years, this method has been increasingly utilized in projects worldwide as it is essential for preventing potential dam safety issues. To address concerns related to seismic safety, this study conducts theoretical analysis, model tests, and numerical simulations to investigate the seismic response of earth-rock dams with polymer antiseepage walls, with a specific focus on the microscopic fluid-solid coupling effect. The dynamic viscoelastic constitutive model used in this study incorporates Biot’s theory of dynamic consolidation and the results of dynamic mechanical analysis (DMA) of polymer materials. To validate the model, a centrifuge test is performed, and it is then utilized to study the seismic response of earth-rock dams with polymer antiseepage walls. Furthermore, the influence of factors such as fluid-solid coupling, water level, polymer material density, and wall thickness on the seismic response of dams with antiseepage walls is analyzed. Finally, the seismic safety of the earth-rock dam with the polymer antiseepage wall is thoroughly examined. The results emphasize the need to consider the fluid-solid coupling effect, as factors like water level and design parameters of the antiseepage wall significantly impact the seismic response of earth-rock dams with polymer antiseepage walls. Full article

Loess is a special soil with high water sensitivity which covers a large area in Northwest China. Cracks are prone to generate in loess under the arid and semiarid climates, which will provide a preferential channel for water and reduce the mechanical properties of soils. It is of great significance to understand the evolution characteristics and mechanisms of the cracks in loess areas. At present, research on cracks in soils mainly concentrates on the characteristics of different cracking patterns. However, spacing cracks are mostly discussed in materials like rock and concrete rather than soils. The cracking characteristics and mechanisms of spacing cracks in loess are still inadequate. In this research, drying tests of loess are carried out with different sizes of specimens. The parameters of spacing cracks and local strain distributions of the loess samples are obtained via PCAS and DIC methods during desiccation, respectively. The cracking modes, spacing cracking laws like insertion, and the saturation of spacing cracks are revealed. Finally, the size effect on the characteristics of spacing cracks is verified with the discrete element software MatDEM. Full article

The karst carbon sink caused by rock outcrops results in enrichment of the bicarbonate in soil, affecting the physiological process of plants in an all-round way. Water is the basis of plant growth and metabolic activities. In heterogeneous rock outcrop habitats, the impact of bicarbonate enrichment on the intracellular water metabolism of plant leaf is still unclear, which needs to be revealed. In this paper, the Lonicera japonica and Parthenocissus quinquefolia plants were selected as experimental materials, and electrophysiological indices were used to study their water holding, transfer and use efficiency under three simulated rock outcrop habitats, i.e., rock/soil ratio as 1, 1/4 and 0. By synchronously determining and analyzing the leaf water content, photosynthetic and chlorophyll fluorescence parameters, the response characteristics of water metabolism within leaf cells to the heterogeneous rock outcrop habitats were revealed. The results showed that the soil bicarbonate content in rock outcrop habitats increased with increasing rock/soil ratio. Under the treatment of a higher concentration of bicarbonate, the leaf intra- and intercellular water acquisition and transfer efficiency as well as the photosynthetic utilization capacity of P. quinquefolia decreased, the leaf water content was lower, and those plants had low bicarbonate utilization efficiency, which greatly weakened their drought resistance. However, the Lonicera japonica had a high bicarbonate use capacity when facing the enrichment of bicarbonate within cells, the above-mentioned capacity could significantly improve the water status of the leaves, and the water content and intracellular water-holding capacity of plant leaves in large rock outcrop habitats were significantly better than in non-rock outcrop habitats. In addition, the higher intracellular water-holding capacity was likely to maintain the stability of the intra- and intercellular water environment, thus ensuring the full development of its photosynthetic metabolic capacity, and the stable intracellular water-use efficiency also made itself more vigorous under karstic drought. Taken together, the results suggested that the water metabolic traits of Lonicera japonica made it more adaptable to karst environments. Full article

Geochemical lithogenes have been successfully applied as an innovative concept in the field of composition classification and source traceability of geological materials recently. This paper introduces the background of the development of geochemical genes and the construction and application of LG01 and LG03 lithogenes. Based on LG01 and LG03, the LG_CR classification and provenance are applied and verified on a weathering profile, ten gully sedimentary profiles and regional stream sediments in the Wanquan area of Zhangjiakou city, Hebei province, China. The geochemical lithology of the weathering profile shows a gradual variation from basic-like in the bottom rock to acidic-like at the upper soils compositionally with heterogeneity. The classification results on 10 sedimentary gully profiles (each with five samples) indicate that soils at the bottom of the gully system are dominated with 11 types of LG_CR materials, while the top materials are made up of 21 types, reflecting the mixing of the upstream soils. The results of stream sediments from a regional geochemical survey with a scale of 1:200,000 in this area illustrate that the classification results of LG_CR on stream sediments are basically consistent with the petrological results derived from regional geological mapping. Therefore, LG_CR can be used not only as an effective tool for classification and traceability of geological materials but also has great potential in lithological mapping in petrological-overburdened areas. Full article

Polymer anti-seepage wall has been gradually applied in earth-rock dam reinforcement projects as a new seepage control technique. However, due to all-pervasive properties of the new materials and root-like connection between the materials and soils, the interface characteristics between the polymer wall and the earth-rock dam, as well as the interaction behavior of both, are complex and still not clear, which obstruct studying coordination mechanism of dam and wall under earthquake. Therefore, the interface characteristics and interaction behavior of dam and wall were studied in the article. Firstly, the dynamic shear stress-displacement, shear stiffness and damping ratio of the interface between polymer and soil were investigated by ring shear test. In addition, the viscoelastic constitutive model of polymer materials were researched by dynamic mechanical analysis (DMA) test. Based on tests results, a finite element model of earth-rock dam with polymer wall was established, including a non-linear simulation interface element and viscoelastic polymer constitutive model. Next, the validity of the simulation model was verified based on dynamic centrifuge test results. Then, the interaction behavior and seismic response of the dam with polymer wall were explored by using the verified model. The research results provide a scientific basis for the development and application of new-typed polymer anti-seepage wall in reinforcement engineering. Full article

Clay is one of the important base materials in slope restoration. The adhesion of clay–rock interface plays a decisive role in the repairing effect on rock slopes. Fibers and polymers are widely used as a clay improvement method in rock slope repair. In this paper, the friction effect of sisal fiber and polyvinyl acetate (PVAc)-reinforced clay was studied through the design of an indoor rock-like interface sliding model test. Using modelled test results and scanning electron microscope (SEM) images, the reinforced clay was analyzed. The test results showed that the critical sliding angle and maximum static friction force of clay decreased with the increase of moisture content. An excess of fiber content and moisture content weakens the coupling effect of fiber-anchoring clay. Fiber content of 0.8% and PVAc content of 2% had the best effect on enhancing the sliding resistance of clay and provided good adhesion for dangerous interfaces of rock slope at 35° and 45°, respectively. PVAc formed a three-dimensional networked elastic membrane structure to improve the skid resistance and dynamic friction coefficient of the clay. The results provide an effective way for soil improvement and ecological restoration. Full article