To address the lack of clear formulae for calculating the circumferential stress in steel epoxy sleeve-reinforced pipelines under internal pressure, this study constructs a mechanical model based on the specific stress characteristics of these pipelines. Using stress solution methods and deformation compatibility relationships, theoretical formulas for circumferential stress in the pipeline layer, epoxy resin layer, and sleeve layer under internal pressure are derived. The theoretical formulas are validated through numerical simulations using ANSYS software, which includes models with and without flanges. The calculations were performed for common pipelines with outer diameters of 219mm, 660mm, and 1219mm. The results show that the discrepancies between theoretical and numerical solutions of circumferential stress in all layers of both model types are within 10%. Specifically, the circumferential stress in the pipeline layer of the flanged model is lower than that of the non-flanged model and also lower than the theoretical values. The error between the theoretical and numerical solutions for pipelines of different diameters does not exceed 10%, confirming the validity and applicability of the theoretical formulas. This suggests that using the simplified mechanical model for circumferential stress calculations ensures a conservative approach for the structural assessment of pipelines. The formulas provided herein can serve as a reference for the design and evaluation of steel epoxy sleeve-reinforced pipelines under internal pressure.
This study investigates the stability of steel columns subjected to axial compression, focusing on square hollow sections (SHS) with both uniform and non-uniform cross-sections. The stability of fixed-free end SHS columns with uniform cross-sections was initially verified using analytical equations. To obtain the critical load and design buckling resistance for each SHS column, Finite Element Analysis (FEA) was employed. The results indicate that while analytical equations can validate the stability of uniform SHS columns, they are insufficient for columns with non-uniform cross-sections. Consequently, the FEA emerges as a robust alternative for analyzing columns with varying cross-sections along their length. This study highlights the necessity of numerical methods for verifying the stability of structurally complex columns, such as those with perforations for mechanical and electrical applications. The finite element model was validated and applied to non-uniform cross-section columns, providing insights into the stability of these columns under practical conditions. This research aims to offer an alternative analytical approach for structural engineering applications where column stability is critical, especially for non-uniform cross-sectional designs that facilitate handling processes in various engineering scenarios.
Recent observations of global warming phenomena have necessitated the evaluation of the service performance of asphalt pavements, which is substantially influenced by surface temperature levels. This study employed twelve distinct machine learning algorithms—K-neighbors, linear regression, multi-layer perceptron, lasso, ridge, support vector regression, decision tree, AdaBoost, random forest, extra tree, gradient boosting, and XGBoost—to predict the surface temperature of asphalt pavements. Data were sourced from the Road Weather Information System of Iowa State University, comprising 12,581 data points including air temperature, dew point temperature, wind speed, wind direction, wind gust, and pavement sensor temperature. These data were segmented into training (80%) and testing (20%) datasets. Analysis of model outcomes indicated that the Extra Tree algorithm was superior, exhibiting the highest R$^2$ value of 0.95, whereas the Support Vector Regression algorithm recorded the lowest, with an R$^2$ value of 0.70. Furthermore, Shapley Additive Explanations were utilized to interpret model results, providing insights into the contributions of various predictors to model outcomes. The findings affirm that machine learning algorithms are effective for predicting asphalt pavement surface temperatures, thereby supporting pavement management systems in adapting to changing environmental conditions.
The construction phase of concrete face rockfill dams is often marred by prominent panel cracking issues, with a lack of reliable foundations for anti-cracking design. To control tensile stresses and enhance crack resistance during construction, this study focuses on the primary factors influencing concrete panel stress in cold regions and the standards for crack resistance control. Through sensitivity analysis using simulation methods and incorporating case studies from typical projects, the mechanisms behind cracking were elucidated, and relevant recommendations were proposed. The research indicates that environmental temperatures in cold regions play a dominant role in load-related stresses, with daily temperature variations and cold waves acting as inducing factors. The impact of drying shrinkage is minimal under current conditions of adequate water curing, and the effect of panel deflection deformation is small. Regarding constraints, the influence of the bedding constraint is significant, whereas reinforcement measures have a minimal effect. Among performance parameters, casting temperature has a pronounced impact, as do autogenous volume changes and the coefficient of thermal expansion, while the influence of the adiabatic temperature rise varies insignificantly within a certain range. This study holds significant importance for the prevention of cracking in concrete face rockfill dam panels.
Dam deformation monitoring is a critical technical measure to ensure the safe and stable operation of dams. It involves measuring the structural deformation response of engineering dams using monitoring instruments or technological means. By analyzing the regularity and trend of deformation monitoring data, potential safety anomalies can be forecasted and warned against, providing timely and reliable data for the formulation and implementation of risk removal measures. Horizontal displacement, as the most intuitive and effective reflection of the dam's state under the action of internal and external loads and foundation deformation, is an indispensable part of dam safety monitoring. Currently, the plumb line method and the tensioned wire method are mainly used for horizontal displacement monitoring of dams. A plumb line coordinate instrument measures the horizontal deformation in the upstream and downstream directions and the left and right bank directions through two axes, or the radial and tangential horizontal displacements for arch dams. Compared to other principles, optoelectronic plumb line coordinate instruments have better long-term stability and anti-interference ability and are widely used on engineering sites. However, the orthogonality of the two measuring directions of the instrument is often overlooked. This paper starts from the principle of the development of the plumb line coordinate instrument, analyzes the source of instrument orthogonal error, and combines data collection, structural analysis, and experimental verification. By applying methods such as least squares and regression analysis, an effective calibration calculation and error correction method is proposed. This method is then programmed into the developed plumb line coordinate instrument to meet the real-time correction and output of measured values, providing a reliable technical method for the accuracy and continuous real-time remote monitoring of dam horizontal displacement monitoring. It also offers a technical path for the orthogonality testing of plumb line coordinate instruments.
Pile foundations, as one of the main foundation forms for bridges and offshore wind power structures, are prone to scour pits around them under the long-term action of water flow, leading to a decrease in bearing capacity. Traditional pile foundation scour prevention measures, such as the construction of protective jetties and riprap protection, are cumbersome and ineffective. Considering the inevitable generation of a large amount of spoil in engineering construction, by optimizing the performance of cement-stabilized soil, it is expected to use the discarded spoil for pile foundation scour management. Aiming at the underwater anti-dispersive cement-stabilized soil based on kaolin, 67 sets of single-factor rotation experiments were carried out to study the effects of changes in the addition of anti-dispersive agents ethylene-vinyl acetate copolymer (EVA), hydroxypropyl methylcellulose (HPMC) from 0‰ to 1‰, cement content from 8% to 14%, and water content from 1.4 to 2 times the liquid limit on the anti-dispersion performance, fluidity, and 7d and 28d unconfined compressive strength of the cement soil. The results show that the anti-dispersive agent HPMC can maximize the anti-dispersion performance of the cement soil, with the addition increased from 0‰ to 1‰, the anti-dispersion performance of the cement soil increased by 76.1%, but the fluidity decreased by 54.0%, and the strength of the 28d age cement soil increased by about 52.9%. Anti-dispersive agents can be added to quickly improve the anti-dispersion performance of the cement soil in pile foundation scour management, but attention should also be paid to its weakening effect on the fluidity of the cement soil; the increase in water content has the greatest impact on the fluidity of the cement soil, with the water content increased from 1.4 times the liquid limit to twice the liquid limit, the fluidity increased by 80.3%; the cement content increased from 8% to 14%, the unconfined compressive strength of the cement soil increased by more than double, and the anti-dispersion performance increased by 26.8%. Based on the experimental results, the recommended mix ratio of kaolin-based cement soil for pile foundation scour repair is: 0.75‰ EVA addition, 1.6 times the liquid limit water content, 10% cement content.
The construction, maintenance, and repair of civil infrastructure demand substantial economic investment, underscoring the necessity of structural health monitoring (SHM) to mitigate property loss resulting from structural failures. Within the domain of SHM systems, the integration of fiber-optic sensors (FOS) is distinguished by their diminutive size, lightweight nature, resistance to corrosion, and straightforward installation procedures, thus garnering widespread recognition. Despite the voluminous publications addressing this subject, comprehensive surveys employing bibliometric and scientometric methodologies remain scarce. This review scrutinizes 1066 publications spanning the past decade through scientometric examination, delineating publication trends, journals of significant contribution, leading researchers, foremost affiliations, and the prevalence of keywords. The analysis reveals a consistent upward trajectory in research activity, with the United States and China emerging as pivotal contributors. Employing VOS viewer for clustering visualization, the study categorizes keywords into discrete clusters, elucidating the breadth of applications and the interconnectedness of topics based on the strength of their associations. This investigation stands as a novel contribution, furnishing a holistic overview of FOS research within SHM, charting historical and current trends, and pinpointing emergent research avenues. The findings are poised to serve as an invaluable repository for scholars endeavoring to incorporate SHM systems equipped with FOS into their forthcoming investigations.
In response to the escalating pressures of urbanization and population growth on the ecosystems and flood risks in Bor County, Jonglei State, South Sudan, this study proposes the implementation of Sustainable Urban Drainage Systems (SUDS) as a resilience-building measure. Through the design of open drainage channels featuring non-uniform flow, inclusive of main and sub-channels alongside infiltration wells, the research aims at mitigating flooding, enhancing water quality, and fostering sustainable development within the region. The necessity for managing substantial runoff volumes has been identified, with a decade of rainfall data employed to accommodate annual variability. The evaluation of SUDS techniques to mitigate flooding entails a customized design approach, integrating cost estimation with flood mitigation strategies and the assessment of short- and long-term co-benefits. Hydrological analysis of ten years of rainfall data facilitated the sizing of channels for storm events ranging from 2 to 5 years, with precipitation intensities between 73.82 and 93.08 mm/day, resulting in the planning of open trapezoidal channels with dimensions to support 5 $m^3/s$ flows. Moreover, infiltration wells, with diameters of 2–3 meters and depths of 3-5 meters, have demonstrated potential in reducing runoff volumes by up to 70% in a 0.5-hectare modelled area. The incorporation of drop structures aims to control slopes ranging from 6-15% in channels, thereby preventing erosion for flows up to 20 $m^3/s$. The adaptability of SUDS approaches, commonly applied in developed nations, to the tropical environment of Bor is scrutinized, highlighting the necessity for localized adaptation due to data limitations and modelling simplifications. The potential barriers posed by capital costs underscore the importance of a life cycle analysis. The success of SUDS implementation in Bor County is contingent upon community engagement, ensuring acceptance and ownership. It is recommended that low-cost, simplistic pilot projects, focusing initially on rain gardens and permeable pavements, precede large-scale implementation. Through strategic planning, SUDS hold the potential to enhance climate resilience in the expanding community of Bor County. An integrated technical analysis provides actionable solutions for flood mitigation, advocating for further monitoring and community-driven initiatives to transition SUDS from concept to reality.
High-grade highways are an important part of the modern comprehensive transportation system. However, due to frequent natural disasters, harsh meteorological conditions, and fragile geological environments, high-grade highway construction projects face significant risks, and how to specifically manage and control these construction risks to reduce them to a socially acceptable level has become a pressing technical issue. Therefore, this study combines the construction characteristics and risk features of high-grade highways, applies the Hall's three-dimensional structural theory to comprehensively identify potential risk factors from the dimensions of time, structure, and logic, and builds the logical dimension from four aspects: people, materials, environment, and management. To filter the main influencing factors, the Delphi method is adopted to construct a risk assessment indicator system, with the expert opinions fully taken into consideration. To address the subjectivity in the weight calculation process of risk assessment indicators, the Analytic Hierarchy Process (AHP) and Entropy Weight Method are used to calculate the subjective and objective weights, respectively. A combined weighting model is established based on game theory principles and is used to optimize the weights of the risk assessment indicators. In view of the fuzziness of risks during high-grade highway construction, fuzzy mathematics theory is introduced to construct the risk assessment model. In this study, this method is applied to the construction of the Elsiyah Highway to clarify the risk level of the project and propose targeted control measures. The results show that the risk level of the Elsiyah Highway project is relatively high. The risk level is conditionally acceptable, but measures must be taken to reduce the risks.
Decades of engineering practice have substantiated that the implementation of construction joints is a pivotal method for mitigating dam cracking. The integration of various joint types, notably transverse and induced joints, within roller-compacted concrete (RCC) arch dams has emerged as a promising strategy to curtail cracking and structural failure. This approach leverages the unique structural characteristics inherent to each joint type. Given the intricate, variable, and dynamic nature of thermal stress in RCC arch dams, the design process for crack prevention, particularly the configuration of induced joints, demands an accurate representation of the dam's operational conditions from construction through to service. Investigations in practical engineering contexts have revealed that the utilization of a contact unit simulation methodology, featuring an open/close iterative function for modeling the behavior of induced and transverse joints in RCC arch dams, proves effective. This method is complemented by the adoption of equivalent strength theory as the criterion for structural integrity assessment. A comprehensive process simulation encompassing the entire dam structure further enhances the efficacy of this approach. Such simulations facilitate a more granular examination of joint placement within the dam and the structural design of the joints themselves. As a result, induced joints can be optimally opened in alignment with design expectations, thereby alleviating tensile stress triggered by temperature reductions. This strategy assures superior construction quality of the dam's concrete body, contributing significantly to the longevity and safety of RCC arch dams.
In response to the mechanical performance alterations of PVC-P geomembranes due to improper handling or subgrade particle action during construction and operation, a series of axial tensile tests on PVC-P geomembranes with various scratch damages were conducted. Multifactorial variance analysis was performed using Python, and a multivariate regression model for the fracture strength and elongation at break of scratched PVC-P geomembranes was developed using SPSS. The precision of the regression model was evaluated using parameters such as the coefficient of determination (R2), mean absolute error (MAE), mean absolute percentage error (MAPE), and root mean square error (RMSE). The results indicated that the fracture strength and elongation at break of PVC-P geomembranes are significantly affected by a combination of scratch angle, length, and depth. The impact on elongation at break is greater than on fracture strength, with the scratch angle having the most significant effect. The developed multivariate regression model yielded R2 values of 0.98 and 0.97 for fracture strength and elongation at break, respectively. The MAEs were 0.62 kN/m and 7.96%, and the MAPEs were 3.06% and 5.13%, respectively. The RMSEs were 0.84 kN/m and 12.08%. The high fitting accuracy of the model suggests its utility for evaluating the mechanical performance of PVC-P geomembranes with scratch damage.
This study introduces a novel methodology for optimizing the design of small dams in the Western Desert of Iraq, a region characterized by its vast expanse and significant flood water influx, particularly in the Horan Valley. The approach integrates Geographic Information Systems (GIS) with a custom-developed Visual Basic program, termed the Optimal Height and Location Model (OHALM), to determine the most effective dam height and location. The initial phase of the study involved utilizing GIS to identify potential dam sites in Horan Valley, based on a set of defined criteria. Subsequently, OHALM was employed to ascertain the optimal dam height, taking into account economic factors such as minimal evaporation losses and maximal water storage capacity. The study culminated in the selection of 13 proposed small dam sites, with height estimations ranging between 12.5 to 14 meters, allowing for a total water storage capacity of approximately 303 million cubic meters. This capacity expansion resulted in an increase of the valley's water body area from 15 square kilometers to 90 square kilometers. Comparative analysis of these proposed dam heights with those of existing structures in the valley revealed a relative variance of 10.4% in the upstream, 7.2% in the midstream, and a comparable percentage in the downstream areas. The research highlights the efficacy of integrating GIS and Visual Basic programming for the strategic development of water resource management systems, particularly in arid regions. This innovative approach demonstrates the potential for significant improvements in water storage and management, addressing the critical need for sustainable water resources in arid environments.
In the realm of civil engineering and industrial construction, the infusion of waste materials into road pavements has emerged as a pivotal strategy for augmenting the attributes of asphalt mixtures while concurrently mitigating the environmental repercussions associated with waste. This investigation delineates a dry method for the preliminary treatment of waste paper, preceding its amalgamation into asphalt mixtures. The focal point is the incorporation of waste paper and Cement Kiln Dust (CKD) as modifiers in Stone Mastic Asphalt (SMA). It is posited that the inclusion of waste paper fibers can substantially elevate the SMA's flexibility and crack resistance. Simultaneously, CKD is purported to bolster the asphalt's strength and durability through its cementitious characteristics. A series of SMA blends were formulated, integrating waste paper and CKD in varied proportions ranging from 0.2% to 1% by weight. Subsequent evaluations encompassed analyses of air voids, density, drain-down characteristics, Indirect Tensile Strength (ITS), and Marshall Stability. The outcomes revealed that the drain-down test exhibited enhancements in volumetric parameters, notably density and air voids. Concomitantly, there was a 33% increase in Marshall Stability and a 37% improvement in ITS. Additional advancements were observed in Marshall Flow, Tensile Strength Ratio (TSR), and skid resistance. In summation, this study establishes that waste paper, when appropriately treated and amalgamated with CKD, can be efficaciously utilized in SMA mixes, yielding mixtures with superior volumetric and mechanical properties. This methodology not only augments the stiffness and minimizes binder drainage but also enhances rutting resistance. Most crucially, it paves the way for sustainable and ethical practices in the reuse and recycling of waste materials.
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