Debris flows are a type of natural disaster induced by vegetation-water-soil coupling under external dynamic conditions. Research on the mechanism by which underground plant roots affect the initiation of gulley debris flows is currently limited. To explore this mechanism, we designed 14 groups of controlled field-based simulation experiments. Through monitoring, analysis, calculation, and simulation of the changes in physical parameters, such as volumetric water content, pore-water pressure, and matric suction, during the debris flow initiation process, we revealed that underground plant roots change the pore structure of soil masses. This affects the response time of pore-water pressure to volumetric water content, as well as hydrological processes within soil masses before the initiation of gully debris flows. Underground plant roots increase the peak volumetric water content of rock and soil masses, reduce the rates of increase of volumetric water content and pore-water pressure, and increase the dissipation rate of pore-water pressure. Our results clarify the influence of underground roots on the initiation of gulley debris flows, and also provide support for the initiation warning of gully debris flow. When the peak value of stable volumetric water content is taken as the early warning value, the early warning time of soil with underground plant roots is delayed by 534 to 1253 s. When the stable peak value of pore-water pressure is taken as the early warning value, the early warning time of soil with underground plant roots is delayed by 193 to 1082 s. This study provides a basis for disaster prevention and early warning of gully debris flows in GLP, and also provides ideas and theoretical basis under different vegetation-cover conditions area similar to GLP.

A tensor-type capillary stress, instead of a scalar suction, has been proposed to serve as a stress-like state variable to capture the effects of capillarity in the mechanics of unsaturated granular soils. However, the influence of water content on the evolution of capillary stress in such soils remains insufficiently understood. This study performs numerical simulations of unsaturated granular soils in the pendular regime using the Discrete Element Method (DEM) involving a volume-controlled capillary bridge model. In these simulations, water content is maintained constant by redistributing the water from ruptured capillary bridges to adjacent ones. The evolution of capillary stress with varying water contents during triaxial and biaxial loading conditions is systematically examined. The DEM simulation results show that, under both loading conditions, the mean component of the capillary stress generally decreases, while its deviatoricity gradually develops. These changes are observed to become less significant as the initial degree of saturation increases. At low saturation levels, capillary bridges between non-contacting particle pairs rupture due to soil deformations, and the water from these ruptured bridges redistributes to existing contacts. This redistribution leads to an anisotropic distribution of pore water aligned with the contact network. At higher saturation levels, non-contacting capillary bridges persist due to their ability to sustain large relative displacements between particles, allowing the spatial distribution of pore fluids to remain less constrained by the solid contact network. Additionally, at higher water contents, relative sliding and particle rearrangement are the primary factors influencing the directional distribution of capillary bridges.

The geogrid-soil interaction, which is crucial to the safety and stability of reinforced soil structures, is determined by the key variables of both geogrids and soils. To investigate the influence of backfill and geogrid on their interface behavior of the reinforced soil retaining walls in Yichang of Shanghai-Chongqing- Chengdu high-speed railway, a series of laboratory pullout tests were carried out considering the influence of water content and compaction degree of the backfill as well as tensile strength of the geogrid. The development and evolution law of pullout force- pullout displacement curves and interface characteristics between geogrid and soil under various testing conditions were analyzed. The results showed that with increasing water content, the geogrid pullout force decreased under the same pullout displacement. The interfacial friction angle of the geogrid-soil interface showed a slowly increasing trend with increasing water content. The variation of the interfacial friction angle ranged between 9.2 degrees and 10.7 degrees. The interfacial cohesion, however, decreased rapidly with increasing water content. With increasing degree of compaction, the interfacial friction angle and the interfacial cohesion of the geogrid-soil interface gradually increased. The change of the interfacial cohesion with the compaction degree was more significant. When the degree of compaction increased from 0.87 to 0.93, the interfacial cohesion increased around 7 times. The tensile strength of geogrid has certain influence on its pullout force-pullout displacement relationship. High-strength geogrid could significantly improve the mechanical properties of the geogrid-soil interface. The investigation results can provide some reference for the design and construction of geogrid reinforced soil structures.

The creep phenomenon of inelastic deformation of surrounding rock may occur under the action of deep geological stress for a long period of time, potentially resulting in large-scale deformations or even instability failure of the underground engineering. Accurate characterization of the creep behavior of the surrounding rock is essential for evaluating the long-term stability and safety of high-level radioactive waste (HLW) disposal repositories. Although the laboratory creep tests of brittle undamaged rocks, such as granite, have been extensively performed, the creep characteristics of fractured surrounding rock under the multi-field coupling environment still require attention. In this study, a series of creep experiments was conducted on Beishan granite, which was identified as the optimal candidate surrounding rock for the disposal repository in China. The effects of various factors, including inclination angle of fractures, stress conditions, temperatures, and water content, were investigated. The experimental results show that the axial total strain increases linearly with increasing stress level, while the lateral total strain, axial and lateral creep strain rates increase exponentially. The failure time of saturated specimens fractured at 45 degrees and 60 degrees is approximately 1.05 parts per thousand and 0.84 parts per thousand of that of dry specimens, respectively. The effect of temperature, ranging from room temperature to 120 degrees C, is minimal, compared to the substantial variations in strain and creep rates caused by stress and water content. The creep failure of specimens fractured at 30 degrees is dominated by rock material failure, whereas the creep failure of specimens fractured at 60 degrees is dominated by pre-existing fracture slip. At a 45 degrees fracture angle, a composite failure mechanism is observed that includes both rock material failure and pre-existing fracture slip. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

In this study, a novel 2D method for measuring soil surface suction, leveraging infrared thermal imaging technology is presented. The main principle of this method is the establishment of a correlation between soil surface water content and a normalized interfacial temperature difference. Subsequently, we link unsaturated soil surface suction to the normalized interfacial temperature difference through the soil-water characteristic curve. To validate the proposed method, an in-situ calibration test was conducted to ascertain the requisite parameters. Then, the method was tested under varying meteorological conditions at two distinct in-situ sites using the same test protocol as the calibration phase. The results demonstrate a strong agreement compared to measured values, affirming the feasibility and robustness of the proposed approach. This method offers several noteworthy advantages, including rapidity, non-contact operation, non-destructiveness, and robustness to environmental fluctuations. It holds promise for advancing investigation of the spatial and temporal evolution of hydro-mechanical properties of in-situ soil under the influence of climate change.

This investigation explores the physiological modulation in Brassica oleracea var. italica (broccoli) in response to treatments with distinct nanoparticles and biochemical elicitors, including copper oxide (CuO), zinc oxide (ZnO), silver nitrate (AgNO3), chitosan, methyl jasmonate (MeJA), and salicylic acid (SA). The study evaluated parameters indicative of plant vitality and stress adaptability, namely chlorophyll a and b concentrations, carotenoid content, relative water content (RWC), and relative stress injury (RSI). The application of chitosan elicited the highest RWC (95.38%), demonstrating its efficacy in preserving cellular hydration under stress, with SA (92.45%) and MeJA (90.53%) closely following. Notably, SA minimized RSI (28.95%), highlighting its superior capacity for mitigating cellular damage under adverse conditions. Comparable stress-ameliorative effects were observed for ZnO and chitosan treatments, suggesting their roles in fortifying membrane integrity. In the context of photosynthetic pigment accumulation, MeJA exhibited the most pronounced effect, achieving maximal chlorophyll a (7.13 mg/g fresh weight) and chlorophyll b (2.67 mg/g fresh weight) concentrations, with SA and ZnO displaying substantial supportive effects. Conversely, AgNO3 treatment was largely ineffective, manifesting the lowest recorded chlorophyll and carotenoid levels across all experimental conditions. Collectively, the findings underscore the potential of MeJA, SA, and chitosan nanoparticles as potent modulators of broccoli's physiological processes, particularly in enhancing photosynthetic efficiency, maintaining water balance, and mitigating oxidative damage under stress conditions. However, before field application, limitations such as the uncertain long-term effects of nanoparticles on plant genomic stability and soil ecosystems, the need for field validation under variable environmental stresses, and the economic feasibility for small-scale farmers must be addressed. Future research should focus on elucidating the molecular mechanisms behind nanoparticle-mediated stress tolerance, conducting eco-toxicity assessments of nanomaterials in agricultural systems, and optimizing cost-effective delivery methods.

Mining leads to soil degradation and land subsidence, resulting in decreased soil quality. However, there are limited studies on the detailed effects of mining activities on soil properties, particularly in western aeolian sand. This study, therefore, quantitatively assessed the aeolian sandy soil disturbance induced by mining activities in the contiguous regions of Shanxi, Shaanxi, and Inner Mongolia. The following soil physical quality indices were measured in the pre (May 2015), mid (October 2015), and postmining period (April 2016), such as the soil water content (SWC), particle size (PS), soil penetration (SP), and soil saturated hydraulic conductivity (SSHC). The results showed that mining activities brought irreversible effects on soil structures. In the pre-mining period, land subsidence broke up large soil particles, destroying soil structure, leading to decreased PS (218.33 vs. 194.36 mu m), SP (4615.56 vs. 2631.95 kPa), and subsequently decreased SSHC (1.12 vs. 0.99 cm/min). Rainfall during the midmining period exacerbated this fragmentation. Thereafter, low temperatures and humidity caused the soil to freeze, allowing the small soil particles to merge into larger ones. Meanwhile, the natural re-sedimentation, subsidence, and heavy mechanical crushing in the post-mining period increased PS and SP. The SSHC hence increased to 1.21 cm/min. Furthermore, the evaluation of soil indices from different stress zones showed that the external pulling stress zone always had a higher SSHC than the neutral zone in any mining period, possibly due to the presence of large cracks and high SWC. This study contributes to the understanding of the impact of mining activities on soil physical qualities, providing a theoretical basis and quantitative guidance for the surface damage caused by coal mining in the aeolian sandy area in Western China.

The high water content of soft soil leads to complex sedimentation, consolidation, and permeability characteristics, posing challenges to engineering design and construction. Although existing research has made progress in the field of consolidation and settlement characteristics, discussions on the low stress stage are still insufficient, and there is a lack of appropriate mathematical models to describe it. At the same time, the correlation and differences between the degree of consolidation used for settlement calculation and the degree of consolidation used for pore water pressure calculation have not been fully clarified. This study improves the measurement method for permeability coefficients and optimizes consolidation equipment, conducting research on the permeability and consolidation characteristics of soft soil with high water content. The research results show that soft soil with high water content exhibits significant consolidation settlement under low stress, and the incremental settlement decreases with the increase of consolidation stress. The void ratio and compression coefficient undergo drastic changes during consolidation, with a difference of 2 to 4 orders of magnitude, especially significant during the low-pressure stage. This study indicates the existence of a critical stress of about 4 kPa and proposes a segmented method to describe the consolidation and permeability characteristics of soft soil with high water content, establishing an e-lg sigma-lgk relationship model, which can effectively reflect the consolidation behavior of super-high water content soft soil. At the same time, the study also finds that in practical engineering applications, the degree of consolidation used for settlement calculation and the degree of consolidation used for pore water pressure calculation should be considered comprehensively to more accurately predict the consolidation process and guide construction.

The use of nanoparticles has emerged as a popular amendment and promising approach to enhance plant resilience to environmental stressors, including salinity. Salinity stress is a critical issue in global agriculture, requiring strategies such as salt-tolerant crop varieties, soil amendments, and nanotechnology-based solutions to mitigate its effects. Therefore, this paper explores the role of plant-based titanium dioxide nanoparticles (nTiO2) in mitigating the effects of salinity stress on soybean phenotypic variation, water content, non-enzymatic antioxidants, malondialdehyde (MDA) and mineral contents. Both 0 and 30 ppm nTiO2 treatments were applied to the soybean plants, along with six salt concentrations (0, 25, 50, 100, 150, and 200 mM NaCl) and the combined effect of nTiO2 and salinity. Salinity decreased water content, chlorophyll and carotenoids which results in a significant decrement in the total fresh and dry weights. Treatment of control and NaCl treated plants by nTiO2 showed improvements in the vegetative growth of soybean plants by increasing its chlorophyll, water content and carbohydrates. Additionally, nTiO2 application boosted the accumulation of non-enzymatic antioxidants, contributing to reduced oxidative damage (less MDA). Notably, it also mitigated Na+ accumulation while promoting K+ and Mg++ uptake in both leaves and roots, essential for maintaining ion homeostasis and metabolic function. These results suggest that nTiO2 has the potential to improve salinity tolerance in soybean by maintaining proper ion balance and reducing MDA level, offering a promising strategy for crop management in saline-prone areas.

The extent of wildfires in tundra ecosystems has dramatically increased since the turn of the 21st century due to climate change and the resulting amplified Arctic warming. We simultaneously studied the recovery of vegetation, subsurface soil moisture, and active layer thickness (ALT) post-fire in the permafrost-underlain uplands of the Yukon-Kuskokwim Delta in southwestern Alaska to understand the interaction between these factors and their potential implications. We used a space-for-time substitution methodology with 2017 Landsat 8 imagery and synthetic aperture radar products, along with 2016 field data, to analyze tundra recovery trajectories in areas burned from 1953 to 2017. We found that spectral indices describing vegetation greenness and surface albedo in burned areas approached the unburned baseline within a decade post-fire, but ecological succession takes decades. ALT was higher in burned areas compared to unburned areas initially after the fire but negatively correlated with soil moisture. Soil moisture was significantly higher in burned areas than in unburned areas. Water table depth (WTD) was 10 cm shallower in burned areas, consistent with 10 cm of the surface organic layer burned off during fire. Soil moisture and WTD did not recover in the 46 years covered by this study and appear linked to the long recovery time of the organic layer.