Further investigation into the progression of soil arching under the impact of noncentered tunnel is warranted. This study addresses this need by examining trapdoor models with varying vertical and horizontal spacings between the tunnel and the trapdoor through the discrete element method. The numerical model underwent calibration utilizing data from previous experiments. The results indicated that the soil arching ratio under the impact of noncentered tunnel exhibits four distinct stages: initial soil arching, maximum soil arching, load recovery, and ultimate stage, aligning with observations unaffected by tunnel presence. The minimal disparity in stress ratio within the stationary region was observed when the vertical spacing between the tunnel and the trapdoor ranges between 150 and 200 mm. Moreover, the disturbed area on the left part of the trapdoor extended significantly beyond the trapdoor width, with notably higher disturbance height compared to the right side. When the tunnel deviated from the centerline of the trapdoor, the stress enhancement on the right side was considerably greater compared to the left. Additionally, the displacement of the trapdoor resulted in a reduction of contact force anisotropy in the soil on the side more distant from the tunnel, while increasing it on the side closer to the tunnel.

Precisely evaluating the soil pressure above parallel tunnels is of paramount importance. In this study, the deformation characteristics of soil above dual trapdoors were analyzed firstly. A novel multi-arch model for calculating the distribution of the vertical earth pressure on deep-buried parallel tunnel was then proposed based on the limit equilibrium method. The height of the dual arch zone caused by the displacement of the dual trapdoors was calculated with consideration of internal friction angle of the soil, width of the trapdoors, spacing between the dual trapdoors, and elastic modulus of the soil. By comparing with numerical simulation results and existing theoretical calculation models that do not account for the interaction of soil arching effect, it is evident that the proposed model in this study adeptly predicts the vertical stress above the trapdoor. Additionally, it captures the characteristic of upwardly convex stress distribution above the trapdoor. The analysis of parameters conducted on the theoretical calculation model showed that the depth of the trapdoor and the internal friction angle of the soil have a substantial impact, whereas the expansion coefficient exerts a negligible effect on the soil arching ratio above the trapdoor.

Background Reactive Red (RR) 141 dye is widely used in various industrial applications, but its environmental impact remains a growing concern. In this study, the phytotoxic and genotoxic effects of RR 141 dye on mung bean seedlings (Vigna radiata (L.) Wilczek) were investigated, serving as a model for potential harm to plant systems.Methods and results Short-term (14 days) and long-term (60 days) experiments in paddy soil pot culture exposed mung bean seedlings to RR 141 dye. The dye delayed germination and hindered growth, significantly reducing germination percentage and seedling vigor index (SVI) at concentrations of 50 and 100 ml/L. In short-term exposure, plumule and radical lengths dose-dependently decreased, while long-term exposure affected plant length and grain weight, leaving pod-related parameters unaffected. To evaluate genotoxicity, high annealing temperature-random amplified polymorphic DNA (HAT-RAPD) analysis was employed with five RAPD primers having 58-75% GC content. It detected polymorphic band patterns, generating 116 bands (433 to 2857 bp) in plant leaves exposed to the dye. Polymorphisms indicated the appearance/disappearance of DNA bands in both concentrations, with decreased genomic template stability (GTS) values suggesting DNA damage and mutation.Conclusion These findings demonstrate that RR 141 dye has a significant impact on genomic template stability (GTS) and exhibits phytotoxic and genotoxic responses in mung bean seedlings. This research underscores the potential of RR 141 dye to act as a harmful agent within plant model systems, highlighting the need for further assessment of its environmental implications.

BackgroundCadmium (Cd) is one of the most important stress factors in plants, with its high mobility in soils, ease of uptake by plants and toxicity at low concentrations. Aluminum (Al) is another phytotoxic metal, the accumulation of which is a crucial agricultural complication for plants, especially in acidic soils. Methods and resultsIn this study, Bryophyllum daigremontianum clone plantlets were obtained from bulbiferous spurs of a mother plant and separated into four different groups and watered with Hoagland solution and mixtures containing 0, 50, 100, and 200 mu M of AlCl3 and CdCl2 each for 75 days. Control groups were maintained under the same conditions without Al and Cd treatment. To simulate acidic soil conditions typical of environments where Al toxicity is prevalent, the soil pH was adjusted to 4.5 by spraying the sulphuric acid (0.2%) with 2-day intervals after each irrigation day. After harvesting, growth parameters such as shoot length and thickness, root, shoot and leaf fresh and dry weights were measured, along with physiological parameters like mineral nutrient status, total protein, and photosynthetic pigment concentrations (chlorophyll a, b, a/b, total chlorophyll, and carotenoid) in both control and experimental groups of B. daigremontianum clones. In response to Al and Cd applications, the plant height, shoot thickness and carotenoid levels were declined, whereas the increments were found in leaf/shoot/root fresh weight, root dry weight, and total protein content. Moreover, differences in genomic alterations were investigated using 21 ISSR and 19 RAPD markers, which both have been used extensively as genetic markers to specify phylogenetic relationships among different cultivars as well as stress-dependent genetic alterations. RAPD primers were used due to their arbitrary sequences and the unknown genome sequence of the plant material used. In contrast, ISSR primers were preferred for a genome-wide genotoxic effect scan via non-arbitrary and more common genetic markers. Distinct types of band polymorphisms detected via RAPD and ISSR markers include band loss, and new band formation under a combination of Al and Cd stress. 17 ISSR and 14 RAPD primers generated clear electrophoretic bands. ConclusionThe study revealed that combined application of Al and Cd affect B. daigremontianum clones in terms of growth, physiology and genotoxicity related to the increasing concentrations.

concrete linings in tunnels constructed by drilling and blasting such as NATM serve as a secondary support structure. However, these linings can face unexpected earth pressures if the primary support deteriorates or if ground conditions becomeunfavorable.It is crucial to determine the loosening earth pressure that allows the lining to maintain its structural integrity and prevent damage caused by this pressure. This study proposes a numerical model for simulating the trapdoor test and developinga method for calculating the loosening earth pressure. The discrete element method (DEM) was employed to describe the soil characteristics around the tunnel. Using this numerical model, a sequence of experimental trapdoor steps was simulated, and the loosening earth pressure was analyzed. Contact parameters were calibrated based on an analysis of a triaxial compression test. The reliability of the developed model was confirmed through a comparison between simulation results and laboratory test findings. The model was used tocalculate the contact force applied to the trapdoor plate and to assess the settlement of soil particles. Furthermore, the model accounted for the soil-arching effect, which effectively redistributes the load to the surrounding areas. The proposed model can be applied to analyze the tunnel's cross-sectional dimensions and design stability under various ground conditions

Mercury (Hg) is recognized as a significant global pollutant, particularly in soils subjected to high anthropogenic activities, such as industrial emissions, agricultural runoff, and mining operations. As Hg contamination in the environment continues to rise, it has become increasingly critical to monitor its detrimental effects on ecosystems and living organisms. To address this concern, the current study focused on assessing the impacts of various concentrations of Hg [0 (Control; Tween 20-containing sterile water), 250, 500, 750, and 1000 UM HgCl2] on the genetic and epigenetic integrity of maize (Zea mays). Specifically, the study investigated DNA damage, DNA methylation patterns, and LTR retrotransposon polymorphism using molecular marker techniques, including Randomly Amplified Polymorphic DNA (RAPD), Coupled Restriction Enzyme Digestion-Random Amplification (CRED-RA), and Inter-Retrotransposon Amplified Polymorphism (IRAP), respectively. The results demonstrated that exposure to high doses of Hg led to a decrease in DNA methylation and a reduction in genomic template stability (GTS%), indicating a destabilization of genomic structure. In contrast, LTR retrotransposon polymorphism increased, suggestingheightened genomic variability due to Hg stress. These findings underscore the genotoxic and epigenetic effects of Hg, with evidence pointing to its ability to alter DNA methylation and activate retrotransposons, which may contribute to genome instability. Furthermore, the observed changes in DNA methylation and retrotransposon activity highlight their potential as reliable biomarkers for assessing exposure to chemical pollutants like Hg in plants. These biomarkers could play a key role in environmental monitoring and in understanding how plants respond to heavymetal stress at the molecular level, offering insights into both short-term and long-term genetic and epigenetic consequences.This study not only advances our understanding of Hg's impact on maize but also reinforces the need for ongoing research into the broader implications of heavy metal exposure on plant genomes and their adaptive responses

This paper reports several plane-strain trapdoor tests conducted to investigate the effects of reinforcement on soil arching development under localized surface loading with a loading plate width three times the trapdoor width. An analogical soil composed of aluminum rods with three different diameters was used as the backfill and Kraft paper with two different stiffness values was used as the reinforcement material. Four reinforcement arrangements were investigated: (1) no reinforcement, (2) one low stiffness reinforcement R1, (3) one high stiffness reinforcement R2, and (4) two low stiffness reinforcements R1 with a backfill layer in between. The stiffness of R2 was approximately twice that of R1; therefore, two R1 had approximately the same total stiffness as one R2. Test results indicate that the use of reinforcement minimized soil arching degradation under localized surface loading. Soil arching with reinforcement degraded more at unloading stages as compared to that at loading stages. The use of stiffer reinforcement had the advantages of more effectively minimizing soil arching degradation. As compared to one high stiffness reinforcement layer, two low stiffness reinforcement layers with a backfill layer of certain thickness in between promoted soil arching under localized surface loading. Due to different states of soil arching development with and without reinforcement, an analytical multi-stage soil arching model available in the literature was selected in this study to calculate the average vertical pressures acting on the trapdoor or on the deflected reinforcement under both the backfill self-weight and localized surface loading.

Underground excavation is usually accompanied by complex soil-structure interaction problems in practical engineering. This paper develops a novel multi-scale approach for investigating the soil arching effect through trapdoor tests. This approach adopts the finite element method (FEM) and smoothed particle hydrodynamics (SPH) method to handle the particle-rigid body interaction in the trapdoor tests, incorporating a micromechanical 3D-H model to derive the nonlinear material response required by the SPH method. The variation of the earth pressure on the trapdoor in simulations exhibits good agreement with those of the experiments. Extensive parametric analyzes are performed to assess the effects of soil height and inter-particle friction angle on the evolution of load transfer and soil deformation. Three deformation patterns are observed under different buried conditions, including the trapezoid, the triangle, and the equal settlement pattern. Results indicate that the planes of equal settlement develop progressively with the trapdoor movement and then enter the range of experimentally observed values. Additionally, three failure mechanisms are identified that correspond to the three deformation patterns. Due to the advantages of the micromechanical model, mesoscale behavior is captured. The anisotropy of stress distribution in the plastic region is found during the arching process.