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Thermal Feasibility of Ground Source Heat Pump Systems for Civil Defense Facilities

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Persistently high cooling loads and strict safety requirements make thermal regulation in civil defense facilities particularly challenging. Conventional cooling systems often struggle to meet long-term efficiency, reliability, and concealment demands. This study evaluates the thermal feasibility of a ground source heat pump (GSHP) system with high concealment for application in the Zhushan civil defense facility in Nanjing, China, aiming to assess its suitability for managing continuous and intensive cooling demands. Numerical Modeling of Ground Heat Exchange A three-dimensional numerical model was developed to simulate coupled flow and heat transfer processes within the ground heat exchanger (GHE). The model incorporates unsaturated porous soil conditions, time-varying fluid flow rates, and environmental disturbances, enabling realistic representation of heat transfer between the circulating fluid, grout, and surrounding soil. This modeling framework provides a robust basis for eval...
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Sustainable Rockfall Protection Using Recycled Tyres for Enhanced Impact Resistance

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  Rockfall hazards present a serious risk to infrastructure in mountainous and hilly regions, demanding mitigation systems that are both mechanically robust and economically viable. Reinforced concrete rockfall barriers are commonly used, yet their performance under high-energy impacts depends heavily on energy-absorbing components. This study investigates innovative and sustainable approaches to enhance rockfall barrier performance, with a particular focus on replacing conventional materials with recycled alternatives. Numerical Modelling of Rockfall Impact A detailed finite element model of a double-anchored reinforced concrete rockfall barrier was developed using Abaqus/Explicit. The barrier was subjected to a high-velocity impact of 25 m/s from a 1 m diameter spherical rock, representing severe rockfall conditions. This numerical framework enabled accurate simulation of impact dynamics, deformation behavior, and energy dissipation mechanisms within the barrier system. Perfo...
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Accident Causality Analysis of Steel Structure Collapses During Construction

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Accidents in the construction sector are widely studied from the perspective of occupational safety, with emphasis on fatalities and injuries. However, construction accidents also have profound impacts on construction processes, project continuity, and structural integrity. Among these, steel structure collapses during construction represent critical events that require systematic investigation. This study addresses this gap by conducting a comprehensive analysis of the causes of steel structure collapses during construction. Steel Structure Collapses as Process Failures Structural collapses during construction are not isolated incidents but complex failures arising from multiple interacting factors. These events often disrupt construction workflows, cause economic losses, and undermine public confidence in engineering practices. Understanding collapses as process-related failures allows for a broader safety perspective beyond individual worker-related incidents. AcciMap Framework f...
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Phosphate Biomineralisation for Sustainable Biocementation in Civil and Geoenvironmental Engineering

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Over the past two decades, biocementation has emerged as a promising technique for ground improvement, crack healing, and the restoration of building materials and heritage stones. Most existing research has focused on calcite-based biocements produced through urea-hydrolysis pathways. However, the generation of ammonia by-products and limited durability in acidic environments restrict the large-scale and sustainable application of these methods. This review introduces phosphate biomineralisation as a novel and environmentally favorable alternative. Limitations of Conventional Calcite-Based Biocementation Microbially induced carbonate precipitation (MICP) and enzymatically induced carbonate precipitation (EICP) rely heavily on urea hydrolysis, which produces ammonia that must be treated or removed. This not only increases environmental risk but also raises operational costs. Additionally, carbonate-based biocements exhibit reduced durability under acidic conditions, limiting their ap...
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Numerical Wavefield Simulation Methods for Ultrasonic Analysis in Civil Engineering

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Interpreting ultrasonic waveforms in civil engineering structures is inherently complex, particularly when tilted boundaries cause multiple reflections, mode conversions, and overlapping echoes. Wavefield simulations have become an essential tool for analyzing such complex signal behavior and supporting non-destructive testing (NDT) applications. This study focuses on evaluating the accuracy and computational efficiency of commonly used numerical simulation methods for ultrasonic wave propagation in civil engineering contexts. Challenges in Ultrasonic Waveform Interpretation Ultrasonic inspections of large civil engineering structures often involve heterogeneous materials and complex geometries that distort waveforms. Tilted interfaces and internal defects introduce signal interference that complicates interpretation. Accurate numerical simulations are therefore critical for understanding wave behavior, validating experimental measurements, and improving defect detection reliability...
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Sustainable Civil Engineering Applications of Non-Metallic Fractions of Waste Printed Circuit Boards (NMF-WPCBs)

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The rapid growth of electronic waste has made the recycling of non-metallic fractions of waste printed circuit boards (NMF-WPCBs) a pressing environmental challenge. Due to their complex composition, NMF-WPCBs are often landfilled or incinerated, leading to secondary pollution and loss of valuable resources. This review addresses the urgent need for sustainable reuse pathways by examining the potential of NMF-WPCBs as functional materials in civil engineering applications. Multiscale Composition and Material Characteristics NMF-WPCBs are composed of polymers, glass fibers, and residual fillers arranged in a multiscale structure that governs their mechanical and chemical behavior. Understanding these characteristics is essential for their effective integration into construction materials. The review analyzes their physical, thermal, and microstructural properties, which influence bonding, durability, and overall performance in civil engineering systems. Enhancement Methods and Theore...
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Sustainable Civil Engineering Applications of Non-Metallic Fractions of Waste Printed Circuit Boards

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  The rapid growth of electronic waste has intensified the environmental burden associated with improper disposal of waste printed circuit boards (WPCBs). In particular, non-metallic fractions of WPCBs (NMF-WPCBs) are frequently discarded or incinerated due to their complex composition, leading to secondary pollution and resource loss. This paper provides a comprehensive review of the potential for incorporating NMF-WPCBs into sustainable civil engineering materials as an effective strategy for waste valorization and environmental protection. Composition and Characteristics of NMF-WPCBs NMF-WPCBs consist of a multiscale composite of polymers, glass fibers, and residual fillers, which collectively influence their mechanical, chemical, and thermal behavior. Understanding these characteristics is fundamental for evaluating their compatibility with construction materials. The review examines the microstructural features and material properties that govern performance when NMF-WPCBs a...
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