The current investigation examines the fluctuating behaviour of stiff pavement built on a two-parameter base and is influenced by aircraft loading impacts. This investigation is driven by the necessity for an accurate evaluation of pavement behaviour under elevated stress scenarios caused by aircraft, which can guide pavement design and upkeep. A stochastic numerical model, the vehicle-pavement interaction model (VPI), was created using a comprehensive 3D dynamic model of an aircraft vehicle and stationary runway roughness profiles. The rigid pavement is simulated using a computationally efficient 1D finite element mathematical model incorporating six DOF. The Pasternak model represents the soil medium, incorporating shear interaction between the spring elements. The pavement's irregularities are considered and replicated using a power spectral density (PSD) function. This assembled model was used to investigate the dynamical reaction of concrete pavement vibrations caused by the passing of an aircraft vehicle using MATLAB code. The dynamic governing differential equations of the aircraft's motion are developed and coupled with the pavement system equations. The coupled system is then solved in the time domain using the direct computational integration approach with the Newmark-Beta integration scheme, explicitly utilizing the linear average acceleration method. This approach is employed to resolve the equations that govern and assess the performance of the connected system. The current findings are being compared to existing analytical outcomes to verify the precision of the current coding. The research examined the impact of various pavement and aircraft vehicle behaviors and factors on the dynamic response of pavement, including the speed, main and auxiliary suspension components, mass and the load position of the aircraft, also the damping, random roughness, thickness, span length and elastic constant of the pavement, even, the modulus of subgrade of the foundation, the rigidity modulus of the shear layer. The findings demonstrate notable influences of aircraft speed and pavement surface roughness on various response parameters. Specifically, the results reveal that a higher subgrade modulus leads to decreased deflection, rotation, and bending moments. Conversely, longer span lengths tend to elevate response parameters while simultaneously reducing shear force. In conclusion, the results highlight the significance of critical factors, including velocity and subgrade modulus, in forecasting the performance of pavement subjected to aircraft loads. The present research is confined to the investigation of the dynamic's performance of the VPI simulation of airfield rigid pavement. The findings from this study can be expanded on by paving engineers to improve the structural effectiveness and reliability of the pavement, serving as a basis for subsequent fatigue analysis in response to diverse dynamic loads such as earthquake, temperature and vehicle load.
Collapse pits are highly susceptible to secondary hazards such as underground debris flows and slope instability under mining disturbances. These hazards significantly damage the ecological environment of the mining area. To reduce the geological hazards of collapse pits, grouting is used for management. The diffusion pattern and curing mode of slurry under different grouting pressures were investigated through indoor grouting simulation tests, and industrial tests were carried out to assess grouting effects. The results indicate that the slurry is dominated by penetration diffusion and supplemented by splitting diffusion in the moraine. The penetration distance and diffusion radius of the slurry increase linearly with grouting pressure, while the splitting uplift distance and cured volume increase exponentially with grouting pressure. Splitting diffusion consists of three stages: bulging compaction, splitting flow, and passive uplift. Horizontal splitting has a vertical uplift effect on the formation. The slurry primarily consolidates individual moraine particles into a cohesive mass by filling fractures, binding soil particles, and reinforcing interfaces with the rock mass. For different moraine layer structures, full-hole, segmented, and point-based grouting methods were applied. A composite grouting technique, layered grouting with ring solidification, was also introduced, achieving excellent grouting results. This study provides technical support for managing geological hazards in collapse pits caused by block caving mining disturbances and for green mining practices.
Characterising the mechanical properties of minor bodies is essential for understanding their origin and evolution. Past missions such as Hayabusa2 have landed on asteroids to sample and discover what these bodies are made of. However, there has been conflicting evidence and reports into the physical properties of the granular surface material of these bodies. With future missions such as Japan Aerospace eXploration Agency's Martian Moons eXploration mission landing on Phobos, the understanding and identification of these physical properties is crucial to maximising the scientific output from these missions. Penetrometry, the determination of the reaction force that an object experiences as it penetrates a surface, can help to understand the essential properties of regolith, such as grain size, porosity and cohesion. Results of penetrometry experiments are largely analysed based on empirical models, which presents us with a challenge if we want to apply them to understand granular materials on asteroid surfaces because gravity cannot be eliminated in the laboratory. Hence, it is essential to verify penetrometry as a method and validate penetrometry instrument designs in microgravity. For this purpose, we conducted a microgravity experiment onboard a parabolic flight campaign. Our experiment tested the use of penetrometry in asteroid-analogue environments by investigating samples with varying properties, such as grain size distribution and shape, and then compared to 1 g experiments to understand the role microgravity plays. The experiment provided a substantial database for future analysis. This paper will focus on the design of the experiment and the parabolic flight campaign in which the experiments were conducted. The design decisions and the variables adjusted during the experiment will be discussed, evaluating how these influenced the campaign and its outcomes. We will also provide a snapshot of preliminary results of the data captured during this experiment. For example, we show the effect of cohesion on penetrometer reaction force, with more cohesive materials providing larger reaction forces nearly of the same magnitude of their 1 g counterparts. We also show that penetrometer tip shapes provide different reaction forces and that flat tips provide the largest reaction force compared to the others. The influence of penetration velocity will be investigated further with the aid of theoretical models. Early indications from the results seen so far are promising for future analyses and will provide key information for the analysis of penetrometry data on future missions.
Southeast Tibet is characterized by extensive alpine glaciers and deep valleys, making it highly prone to cryospheric disasters such as avalanches, ice/ice-rock avalanches, glacial lake outburst floods, debris flows, and barrier lakes, which pose severe threats to infrastructure and human safety. Understanding how cryospheric disasters respond to climate warming remains a critical challenge. Using 3.3 km resolution meteorological downscaling data, this study analyzes the spatiotemporal evolution of multiple climate indicators from 1979 to 2022 and assesses their impacts on cryospheric disaster occurrence. The results reveal a significant warming trend across Southeast Tibet, with faster warming in glacier-covered regions. Precipitation generally decreases, though the semi-arid northwest experiences localized increases. Snowfall declines, with the steepest decrease observed around the lower reaches of the Yarlung Zangbo River. In the moisture corridor of the lower reaches of the Yarlung Zangbo River, warming intensifies freeze-thaw cycles, combined with high baseline extreme daily precipitation, which increases the likelihood of glacial disaster chains. In northwestern Southeast Tibet, accelerated glacier melting due to warming, coupled with increasing extreme precipitation, heightens glacial disaster probabilities. While long-term snowfall decline may reduce avalanches, high baseline extreme snowfall suggests short-term threats remain. Finally, this study establishes meteorological indicators for predicting changes in cryospheric disaster risks under climate change.
Invasive plants often express above-ground traits, such as higher growth than native plants, which promote their success. This may reflect low levels of invertebrate herbivory and/or high rates of arbuscular mycorrhizal fungi (AMF) association. However, the root traits that contribute to invasive success are less well known. Moreover, the combined roles of above-ground herbivory, AMF, and root traits in the invasion process are poorly understood. We conducted field surveys at 17 sites along a latitudinal gradient in China (22.77 degrees N to 42.48 degrees N) to investigate the relationships among above-ground herbivory, AMF colonization, and root traits for five pairs of closely related invasive and native Asteraceae plant species. We experimentally manipulated above-ground insect feeding for two of these pairs of plant species in a middle latitude (34.79 degrees N) common garden. We measured above-ground invertebrate abundance, leaf damage, AMF colonization, root morphological traits associated with nutrient uptake, and root soluble sugar concentrations. In the field survey, invasive plants had lower leaf damage and Hemiptera abundances plus higher AMF colonization, thinner roots with more surface area and higher concentrations of root soluble sugars than native plants. Leaf damage decreased with increasing latitude for native plants. In the common garden, invasive plants had lower leaf damage and Hemiptera abundances plus higher AMF and greater surface area of fine roots than native plants. Leaf damage and Hemiptera reduced AMF colonization via a phenotypic effect of reduced fine root soluble sugars. Synthesis: Our results indicate that low above-ground invertebrate herbivory on invasive plants contributes to their success directly by increasing their growth and indirectly via root soluble sugars that increase their AMF colonization. Invasive plants appear to benefit from greater root volume and surface area, but this did not vary with latitude or above-ground invertebrate herbivory. These results highlight the importance of considering above- and below-ground processes simultaneously to understand how they interact to determine plant invasion success.
To investigate the effects of freeze-thaw (FT) cycles on the mechanical properties of coarse-grained soil in southeastern Xizang under different moisture contents, this study focuses on coarse-grained soil from a large landslide deposit in Linzhi City, Xizang. FT cycle tests, triaxial shear tests, and numerical simulations were employed to systematically examine the comprehensive impact of varying FT cycles, moisture content, and confining pressure on the soil's mechanical characteristics. The results show that FT cycles significantly affect the stress-strain behavior of coarse-grained soil in southeastern Xizang. The degree of strain softening increased from approximately 11.6% initially to 31.2% after 15 FT cycles, with shear strength decreasing by an average of 31.8%. Specifically, cohesion decreased by 38% to 55% after 0 to 15 FT cycles, and the internal friction angle decreased by approximately 29% to 32%. Additionally, higher moisture content led to more pronounced strain softening and strength degradation, while increased confining pressure effectively mitigated these deteriorative effects. Numerical simulation results indicated that as moisture content increased from 7.6% to 11.6%, the number of FT cycles required to reach the critical instability state decreased from approximately 150 to 106, and finally to only 15, with the maximum equivalent plastic strain increasing from 0.20 to 2.47. The findings of this study provide key mechanical parameters for understanding the formation and evolution of FT landslide disasters in southeastern Xizang and lay a scientific foundation for the assessment and long-term prevention of cold-region geological hazards.
Rigid pavements built on an expansive subgrade often sustain damage due to differential movement caused by variations in the subgrade moisture content and the resulting swelling pressure. This study aims to introduce an approach based on swelling pressure for analyzing the deformation of rigid pavements. The analysis takes into consideration the effect of soil matric suction on the modulus of subgrade reaction and potential swelling pressure. The numerical analysis was carried out using the pasternak foundation model, wherein the pavement was idealized as an Euler-Bernoulli beam, the pasternak shear layer represented the granular sub-base supporting the pavement, and the expansive soil was modelled using winkler springs. To demonstrate the practical applicability of the proposed model, a case study is presented for an Indian site and the outcomes are presented. The parametric study clearly illustrates that the modulus of subgrade reaction of expansive soil is the most sensitive and significant parameter for improving the flexural response of the pavement. A flowchart outlining the evaluation procedure is included to provide a visual representation of the analysis process.
Although the present use of pesticides in plant protection has limited the occurrence and development of plant diseases and pests, resistance to pesticides and their environmental and health hazards indicates an urgent need for new active ingredients in plant protection products. Recently synthesized coumarin-1,2,4-triazole hybrid compounds have been proven effective against plant pathogenic fungi and safe for soil-beneficial bacteria. Drosophila melanogaster, the common fruit fly, has been used as a model organism for scientific research. Additionally, it is considered a pest since it damages fruits and serves as a carrier for various plant diseases. On the contrary, Orius laevigatus is a beneficial true bug that biologically controls harmful arthropods in agricultural production. In the present study, we performed an adulticidal bioassay against D. melanogaster and O. laevigatus using coumarin-1,2,4-triazole hybrids. Quantitative structure-activity relationship studies (QSARs) and in silico ecotoxicity evaluation elucidated the structural features underlying the compounds' insecticidal activity. The derivative of 4-methylcoumarin-1,2,4-triazole with a 3-bromophenyl group showed great insecticidal potential. A molecular docking study indicated that the most active compound probably binds to glutamate-gated chloride channels.
Mountain tunnels built near faults often suffer from significant permanent deformation and structural dislocation during seismic activity. In this paper, we present a rock-fault-tunnel geological model with a transition area between the hanging wall and the foot wall which allows the free slippery growth inside the area. A time-sequenced load based on design code and fault activity is conducted in this model to simulate dynamic seismic input after fault dislocation. In our case, a reverse fault with a tunnel cross has been created with this method. A 30cm fault dislocation is simulated by putting the displacement boundary of the hanging wall with a compression vector and the seismic wave is input from the bottom boundary as acceleration waveform adjusted to 0.4g. The model simulates the uplift of the hanging wall and the growth of the slip surface, and reveals the extension mechanism of the triangular shear zone of shear rupture of the surrounding rock due to the extrusion of the reverse fault during the propagation of the reverse fault. The seismic wave with a three-way acceleration was input after the dislocation process. The simulation indicates that with the gradual uplift of the hanging wall, the rock body of the fracture zone shows a more significant large deformation flow trend and a more significant horizontal slip flow. Under reverse fault thrust, the width of the shear effect influence zone is around 300m. A decreasing trend of accumulated strain can be found at the interface due to acceleration input. Dislocation-seismic time-sequence loading may underestimate its damage effects.
The recent increase of the air temperature due to the global climate change is considered as one of the important reasons for the wildfires increase in the world, even in areas where the wildfires are not that common. In addition to the various physical damages adversely affecting the ecological balance, harmful gases and solid particles are released into the atmosphere due to wildfires, causing serious health problems. In this study, impacts of the most serious forest fire in modern history of the country lasting 16 days from 23rd of July 2022 in the National Park Bohemian Switzerland in the D & ecaron;& ccaron;& iacute;n district, Czech Republic, were investigated using remote sensing satellite datasets by cloud-based Google Earth Engine (GEE) platform. The normalized difference moisture index (NDMI), normalized burn ratio index (NBR), normalized difference vegetation index (NDVI), land surface temperature (LST) and soil moisture index (SMI) were calculated from Landsat-8 Operational Land Imager and Thermal Infrared Sensor (OLI and TIRS) dataset for the dates of 31st October 2021, 18th June 2022, and 31st October 2022. Relationship of the remote sensing indices were calculated to estimate the impacts of the wildfire. Furthermore, distribution of nitrogen dioxide (NO2) was extracted using Sentinel-5P TROPOMI (Tropospheric Monitoring Instrument) to observe changes before and after the forest fire in the study region. The burnt area approximately 13.20 km2 from the total area of 79.28 km2 was detected using different time series of the remote sensing indices in the national park.