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Volume 2, Issue 2, 2024

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Recent advancements have seen the integration of nanocomposites, composed of clay minerals and polymers, into cementitious materials to enhance their mechanical properties. This investigation focuses on the dynamics of clay-based cementitious nanofluids along a vertical plate, adopting a Jeffrey fluid model to encompass various phenomena. The effects of a first-order chemical reaction and heat generation/absorption are considered, alongside slip velocity and Newtonian heating conditions. The governing equations, represented as partially coupled partial differential equations, have been extended using a constant proportional Caputo (CPC) fractional derivative. Exact solutions were derived employing the Laplace transform technique. A detailed graphical analysis was conducted to elucidate the influence of pertinent flow parameters on the velocity, temperature, and concentration profiles. It was observed that the incorporation of clay nanoparticles results in a reduction of the fluid's heat transfer rate by 10.17%, and a decrease in the mass transfer rate by 1.31% at a nanoparticle volume fraction of 0.04. These findings underscore the nuanced role of nanoparticle concentration in modifying fluid dynamics under the studied conditions, providing a validated and precise understanding of nanofluid behavior in construction-related applications. This research not only supports the potential of nanotechnology in improving cementitious materials but also contributes to the broader field of fluid mechanics by integrating complex heating and slip conditions into the study of nanoparticle-enhanced fluids.

Open Access
Research article
Failure Criteria for Subway Tunnels Based on the Load-Unload Response Ratio Theorye
yichao chen ,
honglin cao ,
changchao tian ,
jianbin sun ,
wenhua ji
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Available online: 06-29-2024

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This study employs a combination of geological investigation, numerical simulation, and theoretical analysis to evaluate the applicability of the load-unload response ratio (LURR) theory in urban tunnels. The results indicate that using the sudden increase in the LURR at critical points or the equivalent plastic strain penetration between the tunnel and the ground surface as failure criteria for subway tunnels is feasible. Under critical instability loads, the equivalent plastic strain zones in the surrounding rock penetrate to the surface during the construction phase, leading to severe deformation of the tunnel chamber group and loss of load-bearing capacity in the surrounding rock. During the operation phase, the tunnel lining plays a primary load-bearing role. Under instability loads, a butterfly-shaped failure zone appears in the surrounding rock. These findings can be utilized for the quantitative evaluation of the overall safety margin of urban subway tunnels.

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This study outlines the essential thermal and mechanical properties of wood, steel, and gypsum board, focusing on their application in timber-steel and timber-timber connections, as well as in protected and unprotected connections involving one or more materials. These materials are widely used in structural components, serving various functions, from load-bearing to protective roles. A comprehensive summary of these materials was provided, emphasising the critical importance of understanding their properties for use in numerical simulations and other analytical methods commonly employed in structural design research. The properties of these materials significantly influence the behaviour of connections under various conditions, particularly in fire scenarios or other high-temperature environments. As such, knowledge of these properties is crucial for ensuring the accuracy of design calculations and simulations. Furthermore, selecting appropriate material properties from verified standards and documents contributes to the reliability of numerical analyses. This study aims to consolidate and present these verified properties to facilitate their application in both experimental and computational studies of structural connections.
Open Access
Research article
Site-Specific Seismic Ground Response and Liquefaction Potential Analysis of Ranau, Sabah
fatin najiha kamarudin ,
nurfarahin mohd idros
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Available online: 06-29-2024

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The 6.0 moment magnitude scale (Mw) earthquake that struck Ranau, Sabah, on June 5, 2015, resulted in seismic intensities of VI to VII, significantly increasing the seismic vulnerability of buildings in the region. This study presents an analysis of the site-specific seismic ground response and liquefaction potential for the Ranau District, East Malaysia. Ground response spectra were generated for 15 borehole sites, applying a 5% damping factor at ground level using both global and local input ground motions. Seven global and five local seismic records were processed using a one-dimensional equivalent linear approach via DEEPSOIL software. The LiqIT software, based on the Boulanger and Idriss method, was employed for the liquefaction analysis. Ground amplification in Ranau was found to range between 1.281 and 5.132, with peak ground acceleration (PGA) reaching an average maximum of 0.314 g at the surface. Soil periods across the region varied from 0.05s to 1s, consistent with the specifications outlined in the Malaysian National Annex for Sabah (MS EN 1998-1:2015). The results confirmed that the Ranau District is not prone to liquefaction, offering valuable insights for the structural design of future constructions in the area.

Open Access
Research article
Strength-Adaptive Blast Design for Optimized Rock Fragmentation and Controlled Ground Vibrations
nidumukkala sri chandrahas ,
yewuhalashet fissha ,
nageswara rao cheepurupalli
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Available online: 06-29-2024

Abstract

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Achieving efficient fragmentation and minimizing ground vibration in blasting operations necessitates a precise understanding of bench geology, structural dimensions, and the compressive strength of the rock. This study presents a novel blast design approach that integrates compressive strength-driven adjustments to decking lengths and firing patterns, aiming to balance effective fragmentation with safe peak particle velocity (PPV) levels. A series of 36 trial blasts was conducted to assess the impact of decking and firing configurations tailored to specific rock strengths, supported by advanced software simulations and field laboratory testing. Results indicated that a combination of 3.5 m decking length with a V-pattern firing arrangement yielded optimal outcomes for rocks exhibiting compressive strengths between 40 and 50 MPa. This configuration achieved a mean fragmentation size (MFS) of 0.21 m and a PPV of 1.11 mm/s, demonstrating its suitability for controlled and efficient blasting. The findings underscore the critical role of rock strength in guiding blast design and provide mining engineers with practical insights for improving blast efficiency and safety. This study contributes to the development of adaptable blasting models that account for geological variability, paving the way for more precise control over fragmentation and ground vibration in complex mining environments.
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