Search results

The purpose of this paper is to understand a flameproof distance necessary to avoid the flame harms to underground personnel which may have great significance to the safety of underground personnel and the disaster relief of gas explosions in coal mines.

Through a roadway with a length of 100 m and a cross-section area of 80 mm×80 mm, the flame propagation of premixed methane-air deflagrations were simulated by using AutoReaGas software for various fuel concentrations (7, 8, 9.5, 11, and 14 percent), fuel volumes (0.0128, 0.0384, 0.064, and 0.0896 m3), initial temperatures (248, 268, 288, 308, and 328 K), and initial pressures (20, 60, 101.3, 150, and 200 kPa).

The maximum combustion rate for each point follows a changing trend of increasing and decreasing with the distance increasing from the ignition source, and it increases with the fuel volume increasing or the initial pressure increasing, and decreases with the initial temperature increasing. However, increasing the initial temperature increases the flame arrival time for each point. The flameproof distance follows a changing trend of increasing and decreasing with the fuel concentration increasing, and it linearly increases with the fuel volume increasing or the initial temperature increasing. However, the flameproof distances are all 17 m for various initial pressures.

Increasing initial temperature increases flame arrival time for each test point. Flameproof distance increases and then decreases with fuel concentration increasing. Increasing fuel volume or initial temperature linearly increases flameproof distance. Initial pressure has little impact on the flameproof distance.

The COVID-19 pandemic has brought profound changes to all sectors of society including the construction sector. The main purpose of this study is to explore and provide insights into the impact and changes that have occurred in the construction sector due to COVID-19 and to present a mitigation framework to minimize the effects.

The scope of this study is limited to peer-reviewed articles in Scopus or Web of Science indexed journals. A systemized review was performed with bibliometric and content analyses of articles related to the impact of COVID-19 on the construction sector.

Through content analysis, the main topics discussed in the selected articles were grouped into 10 categories. Most of these studies were found to have focused on the challenges, impact, and health and safety at construction sites resulting from the pandemic. The study further identified 39 subtopics through detailed content analysis and organizes them into the categories of negative impacts, positive impacts and opportunities and barriers to COVID-19 safety guidelines in the construction sector. Moreover, the study developed a systematic mitigation strategy based on the recommendations of the literature review to reduce the impact of the current pandemic on the construction sector. The mitigation strategy presents separate set of measures regarding safety guidelines, process improvements, government intervention, psychological support and technology adoption.

The research insights provided in this study are useful for practitioners in guiding them to design effective strategies for addressing the challenges of the COVID-19 pandemic and future crises. Furthermore, a systematic presentation of the impacts, challenges and mitigation measures in this study will help researchers to identify existing gaps in the literature and explore other aspects of the impact of the pandemic on the construction sector.