The digging mechanism is the component of garlic harvesters that consumes the most energy. Consequently, there are theoretical gaps in the design of resistance reduction. These gaps are due to the complexity of the interaction dynamics between the shovel and the soil, and the insufficient understanding of the evolution patterns of soil damage. To address these challenges, this study develops a finite element model of the shovel-soil system using damage mechanics to characterize nonlinear interaction mechanisms under operational loading conditions. The methodology integrates three critical phases: (1) soil damage evolution analysis was employed to identify key damage parameters for model calibration; (2) systematic finite element simulations were used to evaluate the effects of system variables-entry angle, shovel blade bevel angle, forward speed, and vibration frequency-on forward resistance; (3) orthogonal experimental optimization of these parameters was carried out. Key results include the following: (i) A nonlinear relationship was identified between variables (entry angle, forward speed, and vibration frequency) and resistance reduction. Furthermore, the threshold for optimal performance was determined. The optimal parameters were identified as an entry angle of 20 degrees, a forward speed of 0.39 m/s, and a frequency of 2.6 Hz. (ii) Validation through soil bin experiments, demonstrating strong agreement between simulated and measured load-displacement responses, confirming the predictive accuracy of the model. The research presented in this paper may offer insights into the principles of low-resistance designs for underground fruit harvesting.

This paper presents a numerical study on the investigation of microscopic mechanism governing the interaction of woven geotextile and angular sand employing the 3D discrete element method (DEM). The surface texture and tensile properties of the geotextile were simulated using overlapping spherical particles, and the angular sand was simulated using rigid blocks. The DEM models were fully calibrated based on previous experimental data. The shear and dilation zones of sand near the interface were quantitatively determined based on particle displacement gradients. Analysis of contact forces was conducted to explain the microscopic mechanism behind the macroscopic strength evolution. The influence of geotextile surface roughness on the shear strength of the geotextile-sand interface is also discussed. The results show that the failure mode of the woven geotextile-sand interface is a combination of particle sliding failure along the geotextile surface and shear failure of the sand within the shear zone above the interface. There is a rapid redistribution of contact forces prior to reaching peak shear resistance, and the average normal contact force within the shear zone remains relatively constant after the peak shear stress is achieved. A completely developed shear zone stabilizes soil deformation, typically after achieving the peak shear resistance.

Chromium (Cr) poses a high ecological risk, however the toxic mechanisms of Cr in different valence states to soil organisms at cellular and molecular levels are not exactly. In this study, the Eisenia fetida coelomocytes and Cu/ Zn-superoxide dismutase (Cu/Zn-SOD) were chosen as the target subjects to investigate the effects and mechanisms of cellular toxicity induced by Cr(VI) and Cr(III). Results indicated that Cr(VI) and Cr(III) significantly reduced the coelomocytes viability. The level of reactive oxygen species (ROS) was markedly increased after Cr (VI) exposure, which finally reduced antioxidant defense abilities, and induced lipid peroxidation and cellular membrane damage in earthworm coelomocytes. However, Cr(III) induced lower levels of oxidative stress and cellular damage with respect to Cr(VI). From a molecular perspective, the binding of both Cr(VI) and Cr(III) with Cu/Zn-SOD resulted in protein backbone loosening and reduced beta-Sheet content. The Cu/Zn-SOD showed fluorescence enhancement with Cr(III), whereas Cr(VI) had no obvious effect. The activity of Cu/Zn-SOD continued to decrease with the exposure of Cr. Molecular docking indicated that Cr(III) interacted more readily with the active center of Cu/Zn-SOD. Our results illustrate that oxidative stress induced by Cr(VI) and Cr (III) plays an important role in the cytotoxic differences of Eisenia fetida coelomocytes and the binding of Cr with Cu/Zn-SOD can also affect the normal structures and functions of antioxidant defense-associated protein.

Naturally occurring phenomenon such as freeze and thaw, wetting and drying, frost heave can significantly compromise the durability and water-resistant characteristics of soil. Over the last two decades, the geotechnical fraternity has sought to stabilize the problematic soil with the conventional additive's (cement and lime) and non-conventional additive's (fly ash, rice husk ash, slag, fibres, etc.). In recent years, there has been a growing interest in enhancing mechanical and durability behaviour of soil, the usage of nanoadditives, such as nanosilica, nanocopper, nanoalumina, nanocarbon fibres, nanocarbon tubes and nanoclay, is gaining popularity. This paper enlightens the published research work carried by various researchers on the durability performance of nanostabilized soil. The results indicate that nanotreated soil experiences reduction in strength as compared to natural soil subjected to durability cycles. From the review of the literature, it can be concluded that the inclusion of nanoadditives is helpful in improving the durability of soil.

A profound understanding of the interaction between loess slopes and tunnels, along with the mastery of protective measures for tunnels crossing loess slopes, is crucial for ensuring the excavation and operation safety of tunnels in loess slope areas. This article summarizes research findings on the loess slope-tunnel system, concentrating on sources triggering failures, the acting mechanism of failures, and strategies for failure mitigation. Loess slopes, serving as the tunnel's bearing medium, may suffer from engineering disturbances during construction and operation, significantly affecting their stability. This is reflected in the intensification of crack formation, water infiltration, and vibration propagation in the slope. The degree of slope-tunnel interaction depends on relative spatial positioning, slope characteristics, and construction parameters. Although extensive research has focused on tunnel deformation in orthogonal systems, oblique systems require additional investigation. At different stages, preventing failure involves three levels: proactive avoidance, proactive mitigation, and passive reinforcement. Traditional approaches involve divide and conquer, but considering tunnels and slopes as an integrated whole is an emerging research area. Innovative technologies, like Negative Poisson's ratio anchor cables and Steel-Concrete Composite Support for challenging loess terrains, are introduced. Applying these technologies in practical engineering is recommended to accumulate experience and support their mature application. This review can offer valuable support for designing, operating, and managing tunnels crossing areas prone to loess landslides.

There is a lack of research on the molecular interactions between clay minerals and geopolymers at the nanoscale, as well as the interfacial mechanism and mechanical behavior of geopolymers, as a highly promising sustainable soft soil reinforcement stabilizer (grouting reinforcement method). In this study, molecular dynamics simulations were used to reveal the interfacial characteristics and the molecular behavior of geopolymer stabilizers and clay minerals. Molecular models of two geopolymers (calcium aluminosilicate hydrate (C-A-S-H) and sodium aluminosilicate hydrate (N-A-S-H)) and two major minerals (montmorillonite and illite) in soft Hangzhou clays were developed. Then, the interfacial characteristics, interaction mechanisms and mechanical behaviors of different geopolymer/clay mineral interface systems were compared. It was found that montmorillonite and illite attract water molecules to aggregate on the mineral surfaces and promote the migration and diffusion of Ca2+ and Na+ at the interfaces. The interfacial interactions of the geopolymer/clay mineral system mainly consisted of electrostatic interactions. Stronger hydrogen bonding interactions occur at the interface of the geopolymer/clay mineral system. The metal cations and the geopolymer stabilizer between the clay mineral layers form a complex ion nest in concert with the aggregated water molecules to stabilize their interfacial interactions. In terms of the mechanical properties, the C-A-S-H stabilizer has a stronger interfacial shear strength. The shear strength of the illite system is stronger than that of the montmorillonite system, but montmorillonite can produce stronger interfacial bonding with the ground polymer stabilizer, and the curing effect is more obvious.

Time-dependent characteristics (TDCs) have been neglected in most previous studies investigating the deviation mechanisms of bridge pile foundations and evaluating the effectiveness of preventive measures. In this study, the stress-strain-time characteristics of soft soils were illustrated by consolidation-creep tests based on a typical engineering case. An extended Koppejan model was developed and then embedded in a finite element (FE) model via a user-material subroutine (UMAT). Based on the validated FE model, the time-dependent deformation mechanism of the pile foundation was revealed, and the preventive effect of applying micropiles and stress-release holes to control the deviation was investigated. The results show that the calculated maximum lateral displacement of the cap differs from the measured one by 6.5%, indicating that the derived extended Koppejan model reproduced the deviation process of the bridge cap-pile foundation with time. The additional load acting on the pile side caused by soil lateral deformation was mainly concentrated within the soft soil layer and increased with the increase in load duration. Compared with t = 3 d (where t is surcharge time), the maximum lateral additional pressure acting on Pile 2# increased by approximately 47.0% at t = 224 d. For bridge pile foundation deviation in deep soft soils, stress-release holes can provide better prevention compared to micropiles and are therefore recommended.