Leakage associated with deformation joints seriously affects tunnel structures. Existing tunnel deformation joint waterproofing structures have high construction costs and inconvenient maintenance requirements. This work proposes a new tunnel deformation joint waterproofing structure. Specifically, this structure combines Ω type water stop, an externally attached water stop, and a concrete component. An impermeability test compares standard waterproofed specimens to improved specimens. Under a variety of deformation joint widths, fatigue loading times, and displacement difference, the variation law of the seepage quantity and impermeability pressure values are obtained. The study also examined the ability of the waterproofing membrane and waterproofing coating to improve on standard practices currently used. The seepage quantity test results indicate a positive correlation of displacement difference and fatigue loading times with seepage quantity. The larger the deformation joint width of the specimen, the more the new construction process demonstrated its ability to resist high fatigue loading times and large displacement differences. As the fatigue loading times increase, the impermeability pressure value of both types of specimens decrease; however, the impermeability pressure value of the improved specimen was less affected, which verifies an increased fatigue resistance. Both waterproofing membranes and waterproofing coatings improve the waterproofing ability of the standard specimen, while the impermeability law demonstrated similar results to the standard process specimen. Ultimately, these findings reveal the value of selecting appropriate deformation joint widths under different practical engineering conditions.

The artificial ground freezing method (AGF) is widely used in underground construction to reinforce the ground and ensure construction safety. This study systematically evaluates the implementation of the artificial ground freezing method in the construction of a metro tunnel cross-passage, with a focus on analyzing the soil’s thermo-mechanical behavior and assessing safety performance throughout the construction process. A combined approach integrating field monitoring and refined three-dimensional numerical simulation using FLAC3D is adopted, considering critical factors, such as freezing pipe inclination, thermo-mechanical coupling, and ice–water phase transitions. Both field data and simulation results demonstrate that increasing the density of freezing pipes accelerates temperature reduction and intensifies frost heave-induced displacements near the pipes. After 45 days of active freezing, the freezing curtain reaches a thickness of 3.7 m with an average temperature below −10 °C. Extending the freezing duration beyond this period yields negligible improvement in curtain performance. Frost heave deformation develops rapidly during the initial phase and stabilizes after approximately 25 days, with maximum vertical displacements reaching 12 cm. Significant stress concentrations occur in the soil adjacent to the freezing pipes, with shield tunnel segments experiencing up to 5 MPa of stress. Thaw settlement is primarily concentrated in areas previously affected by frost heave, with a maximum settlement of 3 cm. Even after 45 days of natural thawing, a frozen curtain approximately 3.3 m thick remains intact, maintaining sufficient structural strength. The refined numerical model accurately captures the mechanical response of soil during the freezing and thawing processes under realistic engineering conditions, with field monitoring data validating its effectiveness. This research provides valuable guidance for managing construction risks and ensuring safety in similar cross-passage and cross-river tunnel projects, with broader implications for underground engineering requiring precise control of frost heave and thaw settlement.

The creep characteristics of soft clays have been studied for decades. However, the lateral deformation of soils is not allowed during the commonly used one‐dimensional consolidation tests, which cannot describe the real deformation features of soils in practice. On the other hand, the influence of drainage distance on the mechanical properties of soil is still controversial, classified as hypothesis A and hypothesis B. For a better understanding of deformation characteristics of soft clay, especially which in long‐terms, a series of conventional oedometer tests as well as novel geometric confined consolidation tests was conducted on soft dredger fill. The results show that the secondary consolidation coefficient of the soil sample C_α would increase firstly, followed by a small decrease with the increase of consolidation pressure generally. C_α would decrease with the consolidation time and also be reduced by preloading. The strain at the completion of primary consolidation would increase with the drainage distance, but the C_α would be affected little. Both compression index C_c and C_α of soft clay would reduce after preconsolidation, in which two parameters show an approximate linear relationship. The creep coefficient of soft clay under the geometric confinement is larger than that under the oedometer test C_αε. However, the trends of the relationship between the creep coefficient and loading are consistent regardless of the confinement conditions.

Calcareous sands are widely distributed across the South China Sea’s continental shelf and coastlines. Understanding their mechanical behavior and microstructural evolution under cementation is critical for coastal engineering applications. While previous studies have investigated cemented calcareous sands, the comparative analyses of particle breakage and microstructural characteristics between cemented and pure sands remain limited. This study combines triaxial compression tests with X-ray CT scanning and Digital Volume Correlation analysis to systematically examine both material types. Pre- and post-loading CT scans enabled the detailed tracking of microstructural transformations. Results demonstrate that cemented specimens exhibit higher strength–stiffness properties with strain-softening behavior compared to pure sand under 200 kPa confining pressures. A quantitative analysis revealed greater particle breakage in cemented sand, while pure sand showed more pronounced increases in particle sphericity and the aspect ratio during deformation, accompanied by reduced porosity variation along specimen height (coefficient of variation decreased from 15.2% to 12.8% for pure sand. Microstructural analysis indicated moderate increases in pore sphericity and reduced anisotropy in both materials. Fractal dimension analysis demonstrated more significant structural reorganization in cemented sands. Both materials exhibited increases in key morphological parameters, including the throat equivalent radius, channel length, pore equivalent radius, and coordination number, with changes being more substantial in cemented sands. Within shear band regions, cemented sands displayed marked reductions in pore and throat quantities. These findings elucidate fundamental relationships between cementation effects and micro–macro mechanical responses, providing theoretical support for geotechnical applications involving calcareous sands.

In civil engineering projects, the practice of partial excavation or backfilling of slopes often results in landslide occurrences because of the redistribution of internal stress within the slope mass. This paper presents the findings from scaled-model tests conducted to investigate the reinforcement of high-fill embankment slopes using anti-slide piles. During the filling process, data were meticulously monitored using strain gauges affixed to the pile bodies and embedded earth pressure cells. The analysis focused on the mechanical behavior, including load–displacement relationships at the pile tops, bending moments, and earth pressures. This study was designed to investigate how anti-slide piles contribute to slope stabilization and to evaluate their load-bearing behavior throughout the backfilling process. Additionally, particle image velocimetry technology was used to capture the variation patterns of the soil surface displacement field, thereby revealing soil displacement deformation and the overall failure mechanism. By integrating mechanical responses with the analysis of the soil displacement field, a more profound understanding of the pile–soil interaction mechanism was attained. This experimental method provided a comprehensive depiction of the entire process, from the initial slope movement to its eventual deformation and failure. The research indicates that a reduction in pile spacing leads to a decrease in the maximum bending moment of the pile body, thereby enhancing slope reinforcement. For the same pile spacing, the pile located on the first-level slope platform shows the smallest horizontal displacement at its top after deformation. The soil on either side of the anti-slide pile disperses outward from the pile body, with the maximum displacement occurring directly beneath the pile tip.