The increasing demand for sustainable agricultural practices has intensified interest in soilless cultivation systems. However, hydroponics is unable to provide mechanical support for plant roots, and traditional soilless cultivation substrates mostly suffer from poor water retention capacity, rapid nutrient loss, and difficulty in precise control. Hydrogel-based soilless cultivation substrates show great potential for application due to their excellent water absorption, water retention and adjustable transparency. In this study, P(AM-co-NIPAM)/gelatin composite hydrogels with adjustable pore structures, mechanical strength and transparency were obtained by regulating the concentration of crosslinker. Soybean seedlings were grown on these substrates to evaluate the effects of hydrogel properties on root and shoot growth. The results demonstrate that hydrogels with optimized crosslink density possess superior mechanical properties, enhanced water retention capacity, and adequate transparency, facilitating both robust plant growth and high-resolution root system observation. We found that under the MBA content of 0.05 %, the hydrogel matrix could significantly promote the growth of aerial part and root system of soybean seedlings, and was conducive to the colonization of root bacteria. This work highlights the potential of controlled hydrogel matrices in soilless cultivation as a sustainable solution to improve root growth environments, enhance resource utilization, and enable dynamic root system studies. Given their adjustable structure and compatibility with plant growth, such hydrogels may also serve as promising candidates for future application in soilless crop production systems, particularly in scenarios where water and substrate optimization are critical to sustainable agricultural practices.

With the Bulk Jupiter accident, the dynamic separation behavior of solid bulk cargoes in sea transportation, which is different from the usual liquefaction of cargoes, has gradually come to people's attention and is an almost empty field that urgently needs to be researched. In this work, we first conducted vibration table tests for bauxite, replaced bauxite with transparent soil with the same particle size distribution and moisture content, and combined image processing and analysis techniques to complete the detailed visualization of the dynamic separation process. Through the above research, this article reveals the essential characteristics of dynamic separation, including the changing rules of layer-wise water content, pore water pressure, particle motion, and pore water migration. It is concluded that the most apparent feature of the dynamic separation process is the generation of a free liquid surface containing fine particles in the upper layer. The article concludes with a systematic study of the dynamic separation of typical mineral soil. The novel experimental system developed in this study contributes to elucidating the mechanism of dynamic separation of minerals and soil from a precise perspective. [GRAPHICS] .

In transparent soil model experiments, fused quartz stands out as the most promising substitute for natural sand. However, there is still a lack of a comprehensive evaluation system to assess the similarity of its mechanical properties to natural sand. Therefore, a similarity evaluation method based on constitutive model simulation is proposed. First, due to the high friction angle characteristic of fused quartz in transparent soil model tests, multiple oedometer compression and shear box tests were conducted on various gradations of fused quartz. Subsequently, a hypoplastic sand model, which is abundant in natural sand data, stable, and has a straightforward calibration process, was then selected for parameter calibration of fused quartz. Finally, the substitutability of fused quartz for natural sand was evaluated by comparing constitutive parameters and shear box simulation, considering factors such as initial void ratio and confining pressure. The results indicate that the hypoplastic sand model accurately captures the shear behavior of fused quartz. Particles with grain sizes ranging from 0.5 to 2 mm weaken the strength of well-graded fused quartz. The findings also suggest that well-graded fused quartz maintains consistent shear behavior with various natural sands. By contrast, the applicability of single-sized fused quartz is limited.

During tunnel excavation in a soft soil stratum, a transparent model test can present the whole failure process, and a similar transparent material with stable physical and mechanical properties is essential for obtaining valid experimental results. Therefore, a new type of similar transparent material was developed in which fused quartz sand served as the coarse aggregate, nanoscale hydrophobic fumed silica powder acted as the binder, and a mixture of n-dodecane and 15# white oil was used as the pore fluid. The key parameters of the developed similar transparent material, including unit weight, internal friction angle, cohesion, and compression modulus, were evaluated. Furthermore, the consistency between the similar transparent material and natural soft soil was verified in three aspects, namely, physical properties, compressive strength characteristics, and shear properties. Finally, appropriate adjustment measures were proposed based on the results of the analysis of variance (ANOVA) and the analysis of range (ANOR) to meet the similarity requirements of parameters under different engineering conditions.

As an innovative technology, transparent soil similar material can actively promote the development of soil model experiments by clarifying the structure, ratio, and strength characteristics. In order to study the factors affecting the mechanical properties of transparent soil materials, fused quartz is chosen as the aggregate material, nano-scale hydrophobic fumed silica is used as the binder, and a mixture of dodecane and No. 15 white oil is employed as the constituent material for transparent soils. In this study, indoor direct shear tests are conducted, and the range method is used to analyze the factors of quartz particle size, binder content and proportion, moisture content and dry density of the mixture solution. The relationship between the strength properties of transparent soil material and the above variables are quantitatively investigated. The results show that the transparent soil similar material can exhibit softening or hardening properties by changing the proportion of influencing factors, which can be suitable to most soils. Dry density has the most significant impact on cohesion while particle size of quartz has the greatest influence on the internal friction angle. The strength parameter of transparent soil has exponential distribution relationship with moisture content and linear distribution relationship with dry density. The cohesion and powder content are distributed exponentially while the internal friction angle and powder content are linearly distributed. As the particle size of quartz increases, the cohesion decreases overall and the internal friction angle increases. The strength parameters of transparent soil have a logarithmic distribution relationship with the unevenness coefficient of particle size and a linear relationship with the curvature coefficient of particle size. This study has established a quantitative control relationship between the key parameters of transparent soil materials and their mechanical properties. The revealed correlations between gradation of particles and strength parameters can serve as a guideline for simulation and visualization techniques based on transparent soils. It is of great significance for the visualization of the evolution mechanisms of geotechnical disasters.

The excavation of the foundation pit impacts the safety, stability, and normal operational functionality of adjacent existing tunnels. With the increasing urban building density, it is becoming more common to conduct foundation pit excavation in close proximity to existing tunnels, which may result in deformation and damage to the tunnels. The impact of foundation pit excavation on adjacent existing tunnels was investigated using a transparent soil scale model and Particle Image Velocimetry technology. The horizontal and vertical distances between the foundation pit and tunnel, as well as the soil consolidation pressure, were individually examined to analyze their respective trends and magnitudes of impact on the maximum vertical deformation of adjacent existing tunnels. The findings suggest that as the excavation depth increases, the deformation of existing tunnels is increasingly impacted by the excavation of foundation pit. However, this impact decreases with greater horizontal or vertical distance between the foundation pit and tunnel. Furthermore, the impact of vertical distance between the tunnel and foundation pit on tunnel deformation is more significant. The pre-consolidation strength of the soil mass significantly impacts the deformation of the existing tunnel. In order to minimize tunnel deformation in practical engineering, constructive recommendations were proposed.

The construction of a power grillage is of great significance for promoting local economic development. Identifying the characteristics of foundation damage is a prerequisite for ensuring the normal service of the power grillage. To investigate the bearing mechanism and failure mode of the grillage root foundations, a novel research method with a transparent soil material was used to conduct model tests on different types of foundations using particle image velocimetry (PIV) technology. The results indicate that, compared to traditional foundations, the uplift and horizontal bearing capacities of grillage root foundations increased by 34.35% to 38.89% and by 10.76% to 14.29%, respectively. Furthermore, increasing the base plate size and burial depth can further enhance the extent of the soil displacement field. Additionally, PIV analysis revealed that the roots improve pile-soil interactions, transferring the load to the surrounding undisturbed soil and creating a parabolic displacement field during the uplift process, which significantly suppresses foundation displacement. Lastly, based on experimental data, an Elman neural network was employed to construct a load-bearing capacity prediction model, which was optimized using genetic algorithms (GAs) and the whale optimization algorithm (WOA), maintaining a prediction error within 3%. This research demonstrates that root arrangement enhances the bearing capacity and stability of foundations, while optimized neural networks can accurately predict the bearing capacity of grillage root foundations, thus broadening the application scope of transparent soil materials and offering novel insights into the application of artificial intelligence technology in geotechnical engineering. For stakeholders in the bearing manufacturing industry, this study provides important insights on how to improve load-bearing capacity and stability through the optimization of the basic design, which can help reduce material costs and construction challenges, and enhance the reliability of power grillage infrastructure.

Micropile groups (MPGs) are typical landslide resistant structures. To investigate the effects of these two factors on the micropile-soil interaction mechanism, seven sets of transparent soil model experiments were conducted on miniature cluster piles. The soil was scanned and photographed, and the particle image velocimetry (PIV) technique was used to obtain the deformation characteristics of the pile and soil during lateral loading. The spatial distribution information of the soil behind the pile was obtained by a 3D reconstruction program. The results showed that a sufficient roughness of the pile surface was a necessary condition for the formation of a soil arch. If the surface of the pile was smooth, stable arch foundation formation was difficult. When the roughness of the pile surface increases, the soil arch range behind the pile and the load-sharing ratio of the pile and soil will increase. After the roughness reaches a certain level, the above indicators hardly change. Pile spacing within the range of 5-7 d (pile diameters) was suitable. The support effect was poor when the pile spacing was too large. No stable soil arch can be formed, and the soil slips out from between the piles.

The use of a micropile group is an effective method for small and medium-sized slope management. However, there is limited research on the pile-soil interaction mechanism of micropile groups. Based on transparent soil and PIV technology, a test platform for the lateral load testing of slopes was constructed, and eight groups of transparent soil slope model experiments were performed. The changes in soil pressure and pile top displacement at the top of the piles during lateral loading were obtained. We scanned and photographed the slope, and obtained the deformation characteristics of the soil interior based on particle image velocimetry. A three-dimensional reconstruction program was developed to generate the displacement isosurface behind the pile. The impacts of various arrangement patterns and connecting beams on the deformation attributes and pile-soil interaction mechanism were explored, and the pile-soil interaction model of group piles was summarized. The results show that the front piles in a staggered arrangement bore more lateral thrust, and the distribution of soil pressure on each row of piles was more uniform. The connecting beams enhanced the overall stiffness of the pile group, reduced pile displacement, facilitated coordinated deformation of the pile group, and enhanced the anti-sliding effect of the pile-soil composite structure.

Transparent soil (TS) presents immense potential for root phenotyping due to its ability to facilitate high-resolution imaging. However, challenges related to transparency, mechanical properties, and cost hinder its development. Herein, we introduce super-transparent soil (s-TS) prepared via the droplet method using low acyl gellan gum and hydroxyethyl cellulose crosslinked with magnesium ions. The refractive index of the hydroxyethyl cellulose solution (1.345) closely aligns with that of water (1.333) and the low acyl gellan gum solution (1.340), thereby significantly enhancing the transmittance of hydrogel-based transparent soil. Optimal transmittance (98.45%) is achieved with polymer concentrations ranging from 0.8 to 1.6 wt.% and ion concentrations between 0.01 and 0.09 molL-1. After 60 days of plant cultivation, s-TS maintains a transmittance exceeding 89.5%, enabling the detailed visualization of root growth dynamics. Furthermore, s-TS exhibits remarkable mechanical properties, withstanding a maximum compressive stress of 477 kPa and supporting a maximum load-bearing depth of 186 cm. This innovative approach holds promising implications for advanced root phenotyping studies, fostering the investigation of root heterogeneity and the development of selective expression under controlled conditions.