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] .

Expansive soils are susceptible to cracking due to significant moisture fluctuations, which can potentially lead to structural instability. Although geogrid reinforcement is widely used to control soil swelling and shrinkage, its effects on cracking behavior are not fully understood. This study investigates the influence of geogrid reinforcement on the cracking behavior of expansive soils by comparing soil samples reinforced with two layers of geogrid to unreinforced samples under evaporation conditions. Crack development was monitored using high- resolution imaging and fluorescence tracing to measure crack depth and calculate surface crack ratio. Additionally, moisture content distribution and evaporation rates were assessed. The results show that geogrid reinforcement reduced the total crack ratio by 1.34% and decreased average crack depth by 43.5%, leading to a more uniform crack distribution with smaller openings. Both internal and external cracks facilitated moisture exchange between the soil and atmosphere. The frictional and interlocking effects at the soil-geogrid interface effectively inhibited cracking and reduced moisture migration. The uniaxial geogrid also induced anisotropy crack restraint, with environmental exposure and geogrid orientation playing critical roles in crack control. Overall, these findings demonstrate the effectiveness of geogrids in enhancing the stability of expansive soils and limiting atmospheric influence through crack suppression.

In order to address the issue of surface deformation in wintering foundation pits in seasonal frozen soil areas due to excavation and freeze-thaw, an indoor scale model test was conducted to examine the displacement relationship between pit wall soil and supporting structures under freeze-thaw conditions, as well as the temperature change and water migration of soil surrounding the foundation pit. The distribution mode of surface settlement under excavation and freeze-thaw conditions was examined and a surface settlement calculation model was established based on the maximum value of surface settlement. The water will move from the frozen to the unfrozen region as a result of the freeze-thaw cycle. About 1.1 m is the freezing depth. An increase in surface settlement will result from the coordination of deformation between the soil and the supporting structure during freezing and thawing. The greatest surface settlement value following the initial freeze-thaw cycle is 1.082 mm, which is around 215% greater than that of excavation. The skewed distribution is comparable to the surface settlement curves produced by excavation and freeze-thaw cycles. The calculated model's results and the measured settlement values agree rather well.

Rainfall infiltration affects permafrost-related slope stability by changing the pore water pressure in soil. In this study, the infiltration responses under rainfall conditions were elucidated. The instantaneous profile method and filter paper method were used to obtain the soil-water characteristic curve (SWCC) and hydraulic conductivity function (HCF). During the rainfall infiltration test, the vertical patters of volumetric moisture contents, total hydraulic head or suction and wetting front were recorded. Advancing displacement and rate of the wetting front, the cumulative infiltration, the instantaneous infiltration rate, and the average infiltration rate were determined to comprehensively assess the rainfall infiltration process, along with SWCC and HCF. Additionally, the effects of dry density and runoff on the one-dimensional vertical infiltration process of soil columns were evaluated. The results showed that the variation curve of wetting front displacement versus time obeys a power function relationship. In addition, the infiltration rate-time relationship curve and the unsaturated permeability curve could be roughly divided into three stages, and the SWCC and HCF calculated by volumetric moisture content are more sensitive to changes in dry density than to changes in runoff or hydraulic head height.

The efficiency of geosynthetics has been proven in stone column -reinforced foundations. In this paper, loading tests were conducted on three stone column -reinforced foundations, experiencing four freeze -thaw cycles. The effects of geosynthetic encasement and lateral reinforcement were investigated on the behavior of ordinary stone column (OSC) - reinforced and geosynthetic encased stone column (GESC) - reinforced foundation. The results showed that particles of OSCs spread into foundation soil during freezing and thawing, and top of OSCs were replaced by foundation soil. The temperature gradient along the depth in OSC-reinforced foundation was smaller than in GESC-reinforced foundations, resulting in a lower negative pore pressure at the beginning of freezing. However, it was found that geosynthetic encasement helped maintain the integrity of GESCs, and increased the stress concentration ratio (SCR) during thawing, which led to a lower excess pore pressure in GESC-reinforced foundations. The lateral reinforcement was also found to not only reduce the differential settlement between GESCs and soil during thawing, but also restrain the frost heave during freezing. The tensile membrane effect of lateral reinforcement redistributed the stress and the overburden pressure throughout the freeze -thaw process. More water moved upwards during freezing in the OSC-reinforced foundation, leading to a larger amount of frost heave. However, the moisture migration became complex in the OSC-reinforced foundation, as OSCs were damaged by freeze -thaw cycles.

This study investigates the dynamic evolution of cracks in expansive soil under varying wet-dry cycles, employing a self-developed three-dimensional spatiotemporal crack evolution model testing system. The research includes experiments, spatial moisture migration analysis, resistivity monitoring, and crack distribution inference to elucidate the crack development mechanisms. The findings reveal distinct stages in moisture evaporation at different soil depths, characterized by initiation, stability, deceleration, and residual phases. The influence of wet-dry cycles on evaporation rates is pronounced, particularly in deep soil layers. Resistivity changes in expansive soil during moisture evaporation display specific phases, demonstrating their potential to characterize crack development. The study validates the feasibility of assessing crack development through soil resistivity changes. Crack formation initiates at weak points on the soil surface, with subsequent elongation and secondary crack development, resulting in a crack network. Further moisture evaporation and volume shrinkage widen cracks, while wetting leads to crack healing. Total crack length, average width, and area crack ratio decrease exponentially with soil depth, but increase at different depths with more wet-dry cycles. Volume crack ratio initially rises and then stabilizes, while volume shrinkage capacity diminishes until equilibrium. Wet-dry cycles promote crack development, modifying particle arrangements. This research underscores that soil cracking and crack development result from the evolving balance of moisture-induced stresses in space, stemming from non-uniform moisture distribution. In conclusion, this study sheds light on crack development mechanisms in expansive soil under wet-dry cycles, offering valuable insights for soil engineering and geotechnical applications.

In this paper, an experiment study was carried out to identify the fundamental behavior of geosynthetic-encased stone column (GESC) reinforced foundation under freeze-thaw cycles. Three loading tests under four freeze-thaw cycles were considered. A 10-m thick reinforced foundation unit consisted of four floating GESCs with 2.5-m underlain clay layer, and the foundations were preconsolidated to three different initial degrees of consolidation (U = 1.0, 0.6 and 0.3, respectively). The results showed that soil near GESCs had a larger frozen depth due to the excellent heat transfer ability of GESCs. An extra uneven subsidence of soil also appeared around GESCs. Voids could be found between foundation soil and the loading plate after thawing, which indicated that only GESCs carried the overburden pressure. The GESCs showed outward bending under lower initial degree of consolidation, while inward bending under higher one. A bulging failure was observed on frozen part of GESCs, especially at the connection of encasement in foundation with lower initial degree of consolidation. In the first freezing process, a rapid decrease in frost heave force was noticed, inferring the fracture of frozen soil. The stress on GESC was found to almost have no change until complete freezing, when the soil was freezing and the stress on soil exceeded that on GESC. Negative pore pressure was observed in the foundation soil, and the absolute value decreased with the increasing overburden pressure. Both the peak positive and negative pore pressures were reduced as the foundation was preconsolidated to a higher degree. The freeze-thaw cycles were also found to generate excess pore pressure in soil during thawing. Moisture migration was also analyzed using Electrical Resistivity Tomography (ERT) method, and the results showed that moisture tended to go upwards and outside the reinforced unit from thawing to freezing, while downwards and inside the unit from freezing to thawing.

Frost heaving in soils is a primary cause of engineering failures in cold regions. Although extensive experimental and numerical research has focused on the deformation caused by frost heaving, there is a notable lack of numerical investigations into the critical underlying factor: pore water pressure. This study aimed to experimentally determine changes in soil water content over time at various depths during unidirectional freezing and to model this process using a coupled hydrothermal approach. The agreement between experimental water content outcomes and numerical predictions validates the numerical method's applicability. Furthermore, by applying the Gibbs free energy equation, we derived a novel equation for calculating the pore water pressure in saturated frozen soil. Utilizing this equation, we developed a numerical model to simulate pore water pressure and water movement in frozen soil, accounting for scenarios with and without ice lens formation and quantifying unfrozen water migration from unfrozen to frozen zones over time. Our findings reveal that pore water pressure decreases as freezing depth increases, reaching near zero at the freezing front. Notably, the presence of an ice lens significantly amplifies pore water pressure-approximately tenfold-compared to scenarios without an ice lens, aligning with existing experimental data. The model also indicates that the cold-end temperature sets the maximum pore water pressure value in freezing soil, with superior performance to Konrad's model at lower temperatures in the absence of ice lenses. Additionally, as freezing progresses, the rate of water flow from the unfrozen region to the freezing fringe exhibits a fluctuating decline. This study successfully establishes a numerical model for pore water pressure and water flow in frozen soil, confirms its validity through experimental comparison, and introduces an improved formula for pore water pressure calculation, offering a more accurate reflection of the real-world phenomena than previous formulations.