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Freeze–thaw cycles are frequently overlooked as a pivotal factor contributing to leakage and structural failures in clayey soil-impermeable barriers used in landfills or tailings repositories in regions subject to seasonal freezing. This investigation explores the recovery and residual strength properties of Jilin ball clay undergoing six freeze–thaw cycles, and assesses the pore structure characteristics through a series of nuclear magnetic resonance (NMR) tests. The results indicate that normal stress has a greater impact on peak recovery strength than dry density and rest periods. Cohesion increases earlier and more significantly during rest periods compared to internal friction angle. Although the pore diameter remains consistent within the micropores during the freeze–thaw cycles, the soil's structural integrity undergoes notable changes. The concluding analysis provides valuable insights for the construction and management of impermeable barriers in landfills or tailings repositories within seasonally frozen areas. [ABSTRACT FROM AUTHOR]

The problem of heavy metal pollution in soil has become a global concern and an urgent environmental issue. Heavy metal Pb2+ is not biodegradable in the natural environment but can rapidly accumulate in the food chain. Consequently, handling Pb2+ pollution is challenging. Adsorption plays a crucial role in controlling the migration and transformation of pollutants in soil, reducing the concentration of metal components. This study focuses on two types of sand with different particle gradations to investigate the migration and adsorption of Pb2+. The research employed isothermal static adsorption and dynamic adsorption tests. The results indicate that the penetration time of the sand column decreases significantly with an increase in initial concentration, flow rate and the proportion of sand 2, and the maximum reduction time is more than 80%. The static equilibrium adsorption data fit better with the Langmuir model, while the dynamic penetration test data align more closely with the Thomas model, with R2 values exceeding 0.9. The adsorption experiments reveal that smaller particle sizes in the sand sample lead to more significant adsorption of Pb2+ in water. Consequently, natural sand sites are unable to effectively prevent the pollution of heavy metal Pb2+ without treatment using specialized methods. The findings of this study can serve as a reference for the remediation and control of heavy metal Pb2+ contaminated sand sites. [ABSTRACT FROM AUTHOR]

This note examines the interaction between the helices of a multi-helix anchor in terms of the mobilized drained capacity response in tension. Assessments are made on the basis of centrifuge tests in dense silica sand, supplemented with data from existing studies. The centrifuge tests were designed to isolate potential anchor installation effects from those due to the interactions between helices. The data show that additional helices will only contribute to anchor capacity if they are located outside the region of soil mobilized in the failure mechanism of the lower helices. In the dense sand considered in these centrifuge tests, this required helices to be separated by greater than nine diameters, and hence for the lowermost helix to be located at a depth greater than nine diameters. This separation distance is much higher than suggested in previous studies, which tended to attribute the low or nil contribution of additional helices to the soil disturbance generated during anchor installation. Key words: helical anchor, sand, capacity, centrifuge tests, plate. Cette note examine l'interaction entre les helices d'une ancre multi helices en termes de reponse en capacite drainee mobilisee. Les evaluations sont effectuees sur la base d'essais en centrifugeuse dans du sable de silice dense, completes par des donnees provenant d'etudes existantes. Les essais en centrifugeuse ont ete con'us pour isoler les effets potentiels de l'installation d'ancrage de ceux en raison des interactions entre les helices. Les donnees montrent que des helices supplementaires ne contribueront a la capacite d'ancrage que si elles sont situees en dehors de la region du sol mobilisee dans le mecanisme de defaillance des helices inferieures. Dans le sable dense considere dans ces essais de centrifugation, cela impliquait de separer les helices de plus de neuf diametres et donc de placer l'helice la plus basse a une profondeur superieure a neuf diametres. Cette distance de separation est beaucoup plus grande que ne le suggeraient les etudes precedentes, qui tendaient a attribuer la contribution faible ou nulle d'helices supplementaires a la perturbation du sol generee lors de l'installation de l'ancre. [Traduit par la Redaction] Mots-cles: ancre helicoidale, sable, capacite, essais en centrifugeuse, plaque., Introduction Helical anchors have seen widespread use in the electrical power industry and are now being increasingly considered as tie-down anchors for structures subject to uplift loading, tiebacks for slope [...]

Featured Application: The proposed bracing system provides a novel solution for controlling peak seismic responses and for eliminating residual deformation for conventional concentrically braced frames. Multi-story steel frames are popular building structures. For those with insufficient seismic resistance, their seismic capacity can be improved by installing buckling-restrained braces (BRBs), which is known for high energy dissipation capacity, and the corresponding frame is denoted as BRB frame (BRBF). However, BRBFs are frequently criticized because of excessive residual deformations after earthquakes, which impede the post-event repairing work and immediate occupancy. Meanwhile, self-centering braces (SCBs), which were invented with a particular purpose of eliminating residual deformation for the protected structures, underwent fast development in recent years. However, the damping capability of SCBs is relatively small because their hysteresis is characterized by a flag shape. Therefore, this paper aims to combine these two different braces to form a hybrid bracing system. A total of four combinations are proposed to seek an optimal solution. The multi-story steel frames installed with BRBs, SCBs, and combined braces are numerically investigated through nonlinear static and dynamic analyses. Interested seismic response parameters refer to the maximum story drift ratios, maximum floor accelerations, and residual story drift ratios. The seismic analysis results indicate that the frames using the combined bracing system are able to take the advantages of BRBs and SCBs. [ABSTRACT FROM AUTHOR]

The revised smooth particle hydrodynamics method based on the Riemann solution has been used to simulate the interaction process between waves and perforated caissons. In contrast to wave surfaces and opening boundaries of the flume under different wave conditions, the accuracy of the numerical wave flume is verified, and the numerical results are highly consistent with the linear regular wave theory. The reflection coefficient comparison between the values calculated from the smooth particle hydrodynamics method and the test data shows good agreement. The smooth particle hydrodynamics method adopted in this article can be employed to study the reflection coefficient of perforated caissons under conditions of non-overtopping, unbreaking waves. The effects of the related factors on the reflection coefficient are also investigated, including the relative dissipation chamber width B/L and the wave steepness H/L. The wave surface and velocity vector distribution of water particles surrounding the wave dissipation chamber are discussed, including the vortex flow and wave reflux caused by the wave dissipation chamber, which play a significant role in wave energy consumption. The results of this investigation can be used in the hydrodynamic design of perforated caissons and may provide a reference for offshore structural engineering structures. [ABSTRACT FROM AUTHOR]

The revised smoothed particle hydrodynamics method based on Riemann solution has been used to calculate the total horizontal wave force acting on a perforated caisson with a top cover. The interaction process between the wave and perforated caisson is simulated in a two-dimensional numerical wave flume which is verified by linear regular wave theory, water particles flowing in or out of the dissipation chamber are also described in this article, including the distribution of velocity vector. The effect of main non-linear influence factor on total horizontal force is examined here; wave pressure distribution along the height of the perforated caisson in front, inner side or the rear wall of the dissipation chamber is also presented in order to exhibit the more practical performance of perforated caisson with a top cover. The relationship between the total horizontal force and top cover height is anglicized, and the influence of top cover height on components of the total horizontal force is discussed here. A comparison between the numerical total horizontal force results and values tested from the test data is finished; it can be seen that the numerical results agree well with the test data. It is concluded that the smoothed particle hydrodynamics method described in this article can be utilized to calculate the total horizontal force on a perforated caisson with a top cover. [ABSTRACT FROM AUTHOR]

Submarine immersed tube tunnels have been applied in ocean engineering to cross oceans; they have also been used in lakes and rivers. Although the tube tunnel has some advantages such as convenient construction such as low risk and less impact on the surrounding environment, the slope of the excavation foundation pit can collapse easily while the tube tunnel can sink and capsize due to different pore pressures. In order to investigate the construction mechanics effect of a submarine immersed tube tunnel subjected to different pore pressures, two-dimensional finite element analysis is used to simulate the construction of the tube tunnel. During the numerical calculation of a tube tunnel subjected to different pore pressures, the sliding trend of the excavation foundation pit is evaluated while its stresses and deformations are analysed. It can be observed that the two side slopes inside of the excavation foundation can easily slide when not properly reinforced. Without increased loading at their top sides, the tube tunnel structures collapse. [ABSTRACT FROM AUTHOR]