Based on thermal–fluid–solid coupling law in coal and gas outburst, a multi-physical field numerical analysis model is built for the whole outburst process. The response laws of stress, gas pressure, temperature, and seepage in different areas and different time nodes around coal and rock mass in the coal and gas outburst under high stress condition are discussed. Research results show: Firstly, the stress response law of the coal and rock mass around the burst hole is initial vibration–sudden attenuation–late stability. Secondly, the gas pressure response law in different areas is that the gas pressure response rate decreases gradually with the increase of the distance from the outburst. Thirdly, the adsorbed gas contained in the broken coal near the outburst port is desorbed rapidly and expands to do work, and the temperature changes dramatically after outburst occurs. In contrast, with the increase of stress, the proportion of elastic potential in total coal and gas outburst energy increases, and the proportion of elastic potential is positively correlated with stress. The critical gas pressure under the energy condition of coal and gas outburst decreases with the increase of stress. It illustrates that the lower gas pressure can also meet the energy condition of coal and gas outburst under high stress.

Deep mining will increase the likelihood of coal and gas outburst accidents and do harm to the safety of coal mining. In this study, a coal and gas outburst experiment under deep high-stress conditions was carried out and stress-gas pressure-temperature response laws in coal and rock surrounding the burst hole were evaluated. The experimental results showed that the stress response around the burst hole was intense and stress variation decreased as distance from the position to burst port increased. The gas pressure in the coal decreased sharply and oscillated several times during the burst process. The maximum rebound range was 0.05 MPa during this process. The decreasing rate of gas pressure reduced with the increase of the position-burst port distance. The temperature response near the burst port was stronger than peripheral area. The gas internal energy was still the main energy source of coal and gas outbursts, accounting for 75% of the total energy, and played a key role in the burst process. The contribution of elastic potential energy was 22% under deep high-stress conditions in this study. Based on the analysis of burst energy, the gas and stress were key factors of an outburst. K E Y W O R D Scoal and gas outburst, deep high-stress conditions, elastic potential energy, gas internal energy, multiphysics field | INTRODUCTIONCoal and gas outbursts which are dynamic phenomena of mine gas are caused by throwing numerous coals and rocks carrying a great deal of air into the mining space suddenly. [1][2][3][4][5] In the transportation industry, the ejected coal gas can spread for even thousands of meters against the wind or fill in the entire roadway on other conditions. 6-10 A mixture of coal and gas and the fire source in the roadway may cause gas explosions, coal dust explosions, gas and coal dust explosions, and so forth, which seriously harm the safety of mine workers and cause large financial losses. [11][12][13][14][15][16] A series of hypotheses on the mechanism of coal and gas outbursts have been established in major coal-producing countries, including China, Canada, Australia, and Poland, by means of theoretical analysis, laboratory test, numerical simulation, field test, and so forth, 17-21 mainly gas, geostress, synthesis, chemical nature, and synthetic action

Industrial solid waste red mud discharge has caused serious environmental problems. This study utilized red mud as an additive to loessial silt being used for roadway subgrade material. In this study, unconfined compressive test, direct shear test, electrical resistivity test, and hydraulic conductivity test were conducted on red mud stabilized loessial silt (RMLS) with different red mud dosage (DR) to investigate DR effect on mechanical-electrical-hydro properties. Scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses were carried out to reveal the mechanism from micro perspective. The results showed addition of appropriate amount of red mud (30–42%) effectively improved unconfined compressive strength of treated loessial silt but reduced resistivity and hydraulic conductivity. Significant correlation between resistivity and strength performance of RMLS mixture was developed. Microscopic analysis indicates red mud addition will promote generation of hydration products such as calcium silicate hydrations (C-S-H), calcium silicate aluminates hydrations (C-A-S-H), and ettringite (Aft), which will tightly connect surrounding particles of loessial silt and hydrates. Red mud particles adhere to surface of soil particles and fill in pores between them improving a compact and stable structure. This study demonstrated the feasibility of using red mud as a stabilization material for roadway subgrade and proved that resistivity measurement is a nondestructive testing method to evaluate mechanical properties for RMLS mixture.

China has seen a rapid increase in its construction industry in recent years; however, safety conditions of their workers have not improved owing to low education levels and increasing age trend of construction personnel. This study analyzed construction occupations in China from 2010 to 2018 using descriptive analysis, ANOVA and factor analysis. The results showed May, July and August as the deadliest months during the peak of construction activities in the year. No particular day was established as having a higher risk than other days in the week. The most vulnerable times of the day are from 9 AM to 10 AM and 2 PM to 4 PM. A mathematic modeling based on factor analysis, which is the construction safety evaluation score equation, was developed to illustrate regional distribution, and Qinghai Province ranked the worst in construction safety in China. Problems such as poor labor and environment safety management procedures and false reporting or concealed reporting of construction accidents were revealed. Suggestions for improving China’s construction safety were also generated. This study enriched statistical analysis results of construction accidents in China and evaluation modeling with an abundant database will serve as a reference for stakeholders and researchers to improve the construction safety situation in China.

In the process of rapid development of information technology, to promote the further construction of new smart cities, comprehensive utilization of cloud computing technology, big data technology and Internet of Things technology will help improve the convenience of residents’ lives. The development of blockchain technology provides more possibilities for the construction of new smart cities. The use of blockchain and other new technologies to build a smart city big data platform can realize a point-to-point communication mechanism. At the same time, this can also establish a more reliable trust agreement. It is conducive to the realization of applications such as smart IoT, government affairs, and big data. Using the blockchain big data platform to build a new type of smart city can break information islands and achieve the purpose of data sharing and information security. This is a key issue that must be paid attention to in the current construction of new smart cities. In this link, it is necessary to strengthen the research and analysis of blockchain technology to understand the problems that exist in the process of building a smart city on a big data platform. This article discusses the application advantages and related strategies of a smart city big data platform based on blockchain technology.