Based on the fluidic jet theory, this study proposes an effective vortical oscillatory grouting technology. The fluid switching mechanism and pressure pulse characteristics are investigated through numerical simulation and experiment. The slurry diffusion performance of oscillatory grouting is compared with that of steady-pressure grouting under various soil parameters and slurry parameters. The effects of soil interface on diffusion behavior are also studied. The results show that the growth and dissipation of the vortex within the tool generate periodic oscillatory fluid, which further produces pressure pulses. During oscillatory grouting, the pressure recovery process inside the fluidic oscillator reduces the pressure of the soil. With the increase in porosity and particle size, the pressure of the soil grouted by oscillatory pressure is noticeably reduced. Despite the lower pressure of the soil, oscillatory grouting demonstrates better diffusion performance, owing to the dynamic flow field and pressure fluctuation. The performance of oscillatory grouting is also influenced by the oscillatory frequency and pressure pulse amplitude. When the soil interfaces are taken into consideration, different fluid domains exhibit complex slurry diffusion patterns. It is observed that the interface that is perpendicular to the grouting direction has a greater influence on grouting behavior. The oscillatory grouting diffusion behavior is more sensitive to the soil interface. This study is expected to improve grouting efficiency and promote the development of new grouting technology.

Currently, industries seek to optimize the development of technology from energy-saving, economic, and environmental perspectives. Dissolved air flotation (DAF) is one of the most effective wastewater treatment systems. However, it requires considerable energy and causes significant operating costs. A recently emerged application of using fluidic oscillators (FOs) to generate microbubbles has attracted extensive attention, as it consumes much less energy and has proven to be a more energy-efficient technique. In this article, a microbubble generator based on FOs is introduced into the flotation tank, and an energy-saving water treatment system, namely fluidic air flotation (FAF), is presented. Using the computational fluid dynamics (CFD) method, the flow pattern of the FAF is investigated. It is observed that FAF generates a dynamic flow pattern, which is beneficial for bubble removal. At the upper part of the separation zone, the flow pattern exhibits a wavy shape. The flow pattern at the lower part switches between clockwise and counterclockwise. The air distribution of the separation zone is also studied. It is found that the height of the “white water” zone almost linearly decreases with the increase in bubble diameter and diffuser size. FAF consumes almost no energy and occupies a small area, and it is expected to provide a promising solution to develop a new generation of the wastewater treatment system.

Traditional pressure grouting technology operates under steady pressure conditions, causing the grout to easily flow along preferential pathways. This results in uneven grout penetration and increased economic costs. This study proposes swirl grouting technology, which effectively improves this problem. To verify the effectiveness of swirl grouting, a fan-shaped blade tool was also proposed. The grout penetration performance was investigated through experimental studies. The length, width, height, weight, and uniformity of the grouted bodies produced by the swirl grouting method were compared with those produced by the steady pressure grouting method. Then, the mechanisms of swirl grouting were analyzed through transparent disc visualization experiments. The results demonstrated that, at different water–cement ratios, the swirl device increased the penetration length in the X, Y, and Z directions by 43.3%, 27.8%, and 45.8%, respectively, compared to the conventional straight device, and by 57.3%, 39.4%, and 55.6%, respectively, compared to the fan blade device. Moreover, the swirl device increased the weight of the grouted stone body by 54.9% compared to the conventional straight device and by 91.0% compared to the fan blade device, significantly enhancing filling efficiency. The uniformity coefficient of the swirl device permeation decreased by 56.6% and 51.0%, respectively, compared to the conventional straight device and the fan blade device, resulting in a more uniform grout distribution. The transparent disc visualization experiment further revealed the advantage of the swirl device in promoting the migration of fine particles, with a significant increase in average penetration distance and a penetration shape closer to a regular circle. The rotating flow path of the swirl device imparts additional rotational momentum and multidirectional penetration capabilities. The resulting turbulence accelerates the mixing of grout with the soil matrix, facilitating the migration of fine particles, expanding flow channels, and reducing flow resistance. This combination of effects enhances penetration efficiency and reduces energy loss. This study offers significant practical application value for improving engineering quality, construction efficiency, and reducing costs.

Underwater bottom-sitting shell structures face threats from underwater explosion shock waves. To investigate the damage characteristics and dynamic response of bottom-sitting shell structures under underwater explosion shock waves, three-dimensional numerical models of semi-spherical and semi-cylindrical bottom-sitting reinforced concrete (RC) shells under underwater shock waves were established based on the Arbitrary Lagrangian–Eulerian (ALE) algorithm using LS-DYNA software. The influences of the shock wave transmission medium, explosive equivalent, explosive distance, hydrostatic pressure, and reinforcement on the damage characteristics and dynamic response of semi-spherical and semi-cylindrical bottom-sitting RC shell structures were studied. The results indicated that the damage and center vertical deformation of RC shells under underwater shock waves are significantly greater than those under air shock waves. With an increase in explosive equivalent or decrease in explosive distance, the damage and center vertical deformation of RC shells are increased. The damage to the inner surface of RC shells is more severe than the outer surface. The damage and center vertical deformation of RC shells can be reduced by bottom reinforcement and an increase in the diameter of the steel bar. The ‘hoop effect’ caused by hydrostatic pressure restrains the horizontal convex deformation and slightly decreases the macroscopic damage and vertical center deformation of the semi-spherical RC shell with an increase in hydrostatic pressure within the range of 0–2.0092 MPa. The hydrostatic pressure restrains the horizontal convex deformation of the semi-cylindrical RC shell. However, inward concave deformation of the shell center is increased by hydrostatic pressure, inducing an increase in the damage to and center vertical deformation of the semi-cylindrical RC shell. These findings may offer a reference for the construction and design of protective measures for underwater bottom-sitting shell structures.