A three-dimensional seismic response analysis of an asphalt concrete face rockfill dam constructed on a thick overburden layer at the upper reservoir of a pumped-storage power station was conducted using the nonlinear finite element method. The study focused on evaluating the seismic safety of the dam body and the seepage control system. The results indicated that, under the design seismic load, the peak dynamic displacements of the dam body in the horizontal, vertical, and axial directions were 23.87 cm, 10.44 cm, and 26.13 cm, respectively, and the peak accelerations were 2.98 m/s$^2$, 2.01 m/s$^2$, and 2.98 m/s$^2$, respectively. The maximum permanent deformations in the same directions were 18.42 cm, -61.60 cm, and -5.61 cm/18.69 cm, with a settlement ratio of 0.37%. For the asphalt concrete face slab, the peak dynamic displacements in the horizontal, vertical, and axial directions were 23.87 cm, 9.42 cm, and 24.86 cm, respectively. The maximum and minimum principal strains of the face slab after the earthquake were 1.29% and -0.74%. The maximum principal tensile strains of the geomembrane at the reservoir bottom during and after the earthquake were -1.43% and -1.50%. Under the seismic check conditions, the dynamic responses of the dam body, face slab, and geomembrane increased. Comprehensive analysis of the results shows that the seismic response patterns of the dam are consistent with the general characteristics of rockfill dams on thick overburden layers. The dynamic response of the asphalt concrete face slab around the reservoir and the geomembrane at the reservoir bottom did not exceed their respective safety thresholds, indicating that the dam exhibits high seismic safety under seismic loading.

Rapid urbanization in Egbeagu Amansea of Nigeria poses a significant threat to the maintenance of groundwater quality, thus creating a requisite to support effective water management with comprehensive data. This study investigated the hydro-chemical characteristics of groundwater in Awka North, Anambra State. Samples of groundwater were collected from seven boreholes and a hand-dug well during the wet season. These samples were analyzed for physiochemical parameters, such as pH, electrical conductivity (EC), total dissolved solids, total hardness, major cations (Ca$^{2+}$, Mg$^{2+}$, Na$^{+}$, and K$^{+}$), and anions (HCO$_{3}^{-}$, Cl$^{-}$, SO$_{4}^{2-}$, and NO$_{3}^{-}$). The study employed standard hydro-chemical methods, such as Piper and the United States salinity (USSL) diagrams to characterize water types and determine the dominant hydro-chemical processes influencing groundwater chemistry. The results of the Piper trilinear diagram revealed that bicarbonate (HCO$_{3}^{-}$ + CO$_{3}^{2-}$) was the dominant anion, hence reflecting carbonate dissolution in the aquifer. Sodium adsorption ratio (SAR) values ranged from 0.53–0.674, thus classifying all samples in the low (S1) category and indicating minimal sodium hazard for soil. EC values spanned 44–130.6 $\mu$S/cm, placing samples in the low (C1) to medium (C2) categories. The study confirms that the groundwater in the study area is suitable for drinking and irrigation purposes.

Strengthening or rebuilding dangerous sluices to restore their functions is an urgent issue calling for attention in order to guarantee the safety of people’s lives and properties. Based on analytic hierarchy process (AHP), this study analyzed in detail the influences of flood control capacity, seepage, structural and seismic safety, metal structure, electromechanical equipment, and engineering quality on the comprehensive evaluation of sluice gates. It also established a safety evaluation index system for the gates in service in the Tarim River Basin, and applied it to the safety evaluation of 25 sluice gates. The degree of importance of each sluice was quantified by the index of sluice building level and the design of water diversion flow; the calculation method of sluice risk index was established by combining the importance and the safety indices of sluices. The study demonstrated that the safety ranking of 25 sluice gates could corroborate with the safety appraisal results. The ranking of the urgency of derisking were more reasonable and in line with actual situations. This proposed method is simple, practical, and operable to scientifically evaluate the safety and risks of existing sluices, hence exhibiting considerable engineering value for the consolidation and sequencing of dangerous sluices pending for reinforcement.

Negative skin friction induced by surcharge loading represents a critical geotechnical issue, compromising the performance of pile foundations and associated superstructures. Although surcharge-induced negative skin friction has been extensively investigated for single piles, the underlying pile group effect and the effectiveness of isolation piles in mitigating dragload development remain insufficiently understood. To address these gaps, controlled laboratory model tests were conducted on a single pile and a 3 $\times$ 2 pile group subjected to surcharge loading. Axial strains along the pile shafts and pile-head displacements were continuously monitored to quantify the distribution characteristics of negative skin friction, evaluate pile group interactions, and assess the influence of isolation pile spacing on the reduction of negative skin friction acting on engineering piles. The results demonstrated that a pronounced pile group effect was generated under surcharge loading. Relative to the single-pile condition, the average negative skin friction acting on corner piles and center piles was reduced by 10.04% and 15.36%, respectively, indicating that the center pile was more strongly influenced by the pile group effect. Furthermore, the installation of isolation piles was shown to effectively decrease pile-head displacement, pile-shaft stress, and surcharge-induced negative skin friction. The mitigation efficiency was found to be strongly dependent on isolation pile spacing, with closer spacing producing a more pronounced shielding effect. As the spacing between isolation piles and engineering piles was reduced from 6$D$ to 2$D$, the reduction rate of average negative skin friction increased from 7.55% to 20.13%. However, the incremental improvement became progressively less significant when the spacing was smaller than 4$D$. These findings provide experimental evidence for the pile group behavior of surcharge-induced negative skin friction and offer practical guidance for the design and optimization of isolation-pile systems intended to mitigate dragload effects in pile-supported structures.

The problem of cracking gives rise to one of the most serious issues associated with the durability of reinforced concrete. To overcome this shortcoming, the objective of this study involved an experimental investigation of the mechanical properties and self-healing capability of concrete in the presence of bacteria and nanoparticles of silica. Five different mixes had been considered in the experiment and they were: (i) reference mix; (ii) bacterial concrete; (iii) nano-silica concrete; (iv) concrete hybrids made of bacteria and (v) of nano-silica in various ratios. Surprisingly, the mechanical properties and the durability of concrete were largely enhanced, given the existence of bacteria and nanoparticles of silica. A mix of concrete with 4% nanosilica and 106 cells/ml of bacteria indicated maximum compressive strength, which equaled to 58.2 MPa within 56 days compared with 40.2 MPa of the reference sample (44.8% improvement). Meanwhile, the splitting tensile strength could be improved up to 38.2%. Bacteria and silica improve pores refining, resulting in increased matrix density. As regards self-healing ability, impressive results were found in concrete hybrids. Crack-closure of the reference sample was 26.2%, while that of hybrid mix was 93.3%. Scanning electron microscopy (SEM) analysis revealed that hybrid samples included calcium carbonates and C-S-H gel in cracks, whereas self-healing contributed to 95.6% concrete strength restoration. Interestingly, the combined effects of bacteria and nano-silica could help manufacture highly durable self-healing concrete for the construction industry.