Is gas more violent than a tiger? Good news for coal miners! This mine guard has a new way to conquer it

Coal accounts for 73% of my country's energy composition and is the "ballast stone" of my country's energy security. Under the current resource endowment of "rich in coal, poor in oil, and little gas" in my country, the development and utilization of coal resources is related to the sustainable development of the national economy. However, accidents such as gas anomalies, gas explosions, and coal and gas outbursts caused by coal seam mining are becoming increasingly serious, which has always been a key issue plaguing the development of my country's coal industry.

▲Zhao Pengxiang

In recent years, with the rapid development of social economy and the continuous improvement of scientific and technological levels, the incidence of coal mine accidents has dropped significantly, but the problem of gas disasters cannot be ignored. Professor Zhao Pengxiang, deputy director of the Safety Engineering Department of the School of Safety Science and Engineering of Xi'an University of Science and Technology, has been engaged in research and exploration in my country's coal field for more than ten years, and his scientific research work is centered on gas prevention and control.

Keep working hard and strive for a long-term goal. Zhao Pengxiang knows that "not afraid of hardship and fatigue" is the foundation of scientific research in the coal industry. In his scientific research career, half of the 365 days a year he is rooted in the coal mines, discovering and solving problems. To this day, he still remembers what he saw and felt when he first started his scientific research in 2010 and went deep into the Dafosi Coal Mine in the Binchang Mining Area of ​​Shaanxi Province to conduct research and investigation. Although it was tiring, it was more rewarding and satisfying. It is precisely the on-site training over the past decade that has allowed him to accumulate rich experience in the research of multi-field coupling theory of coal seam mining and gas extraction technology, and has made a series of innovative scientific research results.

Conquer the "tiger" of gas and protect the safety of mines. In the front line of the coal industry, Zhao Pengxiang's scientific research ideals were ignited and realized...

Love what you do

Zhao Pengxiang was born in Lanzhou, Gansu Province, east of Lancang River in 1987. Lanzhou is an important central city in western China and an important node city of the Silk Road Economic Belt. Born and raised in this land with rich historical accumulation, Zhao Pengxiang has developed a hard-working character and strengthened his determination to serve the country after completing his studies.

Before going to university, Zhao Pengxiang said frankly that he did not think much about his future studies and development direction. It was not until he was admitted to the safety engineering major of Xi'an University of Science and Technology in 2006 that he began to have a comprehensive understanding of the field of mining safety.

Xi'an University of Science and Technology is the predecessor of Xi'an Mining College and has a long history of coal mine research. The field of coal mine safety technology is also one of the main areas of the school's professional and disciplinary construction. According to reports, the coal-bearing area of ​​the Sanqin area is 57,000 square kilometers, and the predicted coal resources are 380 billion tons, ranking fourth in the country; the cumulative proven coal reserves are 170 billion tons, ranking third in the country. For Shaanxi, coal is not only an important resource for the benefit of the people, but also an important pillar of economic development. As the saying goes, "Do what you love." With the support of the rich local coal resources and the school's rich faculty, Zhao Pengxiang is determined to make his own achievements in the field of coal safety engineering.

During his postgraduate study, Zhao Pengxiang, under the guidance of his supervisor, formally delved into the research direction of gas prevention and control. It was this stage of research enlightenment that opened a window for his future scientific research. Through a series of scientific research practices, Zhao Pengxiang was truly exposed to gas prevention and control theory, gas experiments and on-site gas prevention and control practices. He also found that "this direction is very different from the traditional gas prevention and control. It is mainly after coal mining, the evolution law of overlying rock collapse is combined with gas prevention and control to carry out related field research." After going deep into it, he found that there is a huge space for exploration in this field, and he is determined to continue to explore this direction in the future.

Committed to innovating gas prevention and control technology

It all started with interest and ended with passion. During his doctoral studies, Zhao Pengxiang has always been keen on free exploration work, and scientific research in the coal field has given him unlimited space. In his opinion, doing research work that he likes, drawing nourishment from it, and getting a satisfactory result will give him a sense of accomplishment. Gas prevention and control research is what he wants, and he is willing to work hard and sweat for it.

After graduating with a doctorate and staying at Xi'an University of Science and Technology, Zhao Pengxiang has not stopped exploring the scientific frontiers in this field. In order to get in touch with more advanced scientific research technologies in research fields, he has also traveled to Australia, the United States and other places for academic exchanges and visiting studies. Especially during his visiting scholar period at Northern Arizona University in the United States, Zhao Pengxiang gained a deeper understanding of the local teaching methods, scientific research models and the "people-oriented" mining concept in the United States through what he saw and felt and in-depth exchanges with his co-mentor Professor Chun-Hsing Ho. All this also gave him a new thinking about his research field. Rooted in Xi'an University of Science and Technology for many years, he has been committed to the technical improvement of coal seam mining multi-field coupling theory and gas extraction technology, and has carried out a series of innovative explorations in this direction.

In Zhao Pengxiang's view, in the new era, the means of gas prevention and control must also undergo new changes. For a long time, the occurrence of gas accidents has been closely related to the coal seam conditions, gas conditions, coal seam mining technology and processes, etc. The migration of gas flows into the mining space after the disturbance of coal seam mining, which will pose a huge threat to the mining process. Therefore, the development of mine gas prevention and control cannot only study gas accidents based on gas itself, but should be combined with external environmental factors.

"In the process of gas accidents, mine pressure plays a vital role." Zhao Pengxiang introduced. Mine pressure refers to the stress caused by the deadweight of underground rock before mining. Because the rock before mining is in a state of force balance, the original rock is in a state of balance. When tunnels are excavated or mining is carried out, the original stress balance is destroyed, causing the redistribution of stress inside the rock. When the redistributed stress exceeds the ultimate strength of coal and rock, the coal and rock around the tunnel and mining face are damaged. This situation will continue until the coal and rock reach a new stress balance again.

"If we don't combine the study of mine pressure with gas prevention and control, it will be difficult for us to understand the mechanism of gas outburst, migration, outburst and related disasters," said Zhao Pengxiang. Combining the two will give us a more comprehensive understanding of the gas migration state during coal mining, and we can then arrange the gas extraction system in a targeted manner.

In order to better carry out research in related fields, Zhao Pengxiang's team divided the dominant channels for gas migration into three high-permeability areas at the "low, medium and high" levels, and then made corresponding technical selections based on the actual conditions of each coal seam for gas extraction. Starting from the disaster-causing mechanism of gas, they systematically studied the main controlling factors affecting the amount of gas outburst, including which related areas of the overlying rock formations the gas will migrate, seep, rise and diffuse to after the overlying rock formation collapses, and further refined the evolution and formation process and spatial morphology of these areas, and proposed key technologies for mining-induced pressure relief gas extraction in different regions, which further improved the efficiency of pressure relief gas extraction.

▲Visiting Scholarship Exchange

With the support of solid theoretical foundation and relevant technologies, Zhao Pengxiang successfully applied for a series of national and provincial and ministerial scientific research projects. In recent years, he has presided over and participated in 11 National Natural Science Foundation projects (presided over 2 general projects and 1 youth project), Shaanxi Province Outstanding Youth Science Fund Project and more than ten provincial and ministerial projects. In the pioneering practice of scientific research projects, his scientific research level has also been greatly improved.

Having been rooted in the coal mines for many years, Zhao Pengxiang found that it is sometimes difficult to obtain continuous data at the coal mine site due to the difficulty of observation. At this time, they need to move the on-site working surface to the laboratory in a similar proportion. In this context, in order to ensure the smooth progress of related work, the requirements for laboratory simulation materials and simulation devices will be higher. In the National Natural Science Foundation Youth Fund Project hosted by Zhao Pengxiang, he launched a series of explorations on the material development and solid-gas coupling mechanism of physical similarity simulation experiments. By combining experimental simulation with the field, he found that there is a close connection between the migration process of gas and every collapse of the rock formation. In order to better explore the relationship, Zhao Pengxiang conducted relevant research on the linkage evolution of the fracture field and seepage field in the high permeability zone during coal mining, making the relevant results more universal.

For a long time, coal and gas outbursts have been dynamic disasters controlled by geostress, gas pressure and coal body structure, and are prone to occur in coal seams with developed tectonic coal, and are widely related to tectonic coal. In particular, the combination of primary coal and tectonic coal will produce a series of deformation, expansion, migration and fusion under the joint action of geostress and gas pressure, and gas outbursts often occur in the "dislocation structure" of the coal body. Zhao Pengxiang's research is to find the distribution characteristics, migration process and migration law of the dislocation structure in tectonic coal, and combine it with the coupling relationship between gas desorption and seepage to carry out more innovative exploration.

In the research of a sub-topic of the National Natural Science Foundation key project, Zhao Pengxiang also developed a set of comprehensive equipment that integrates fracture observation, gas concentration detection, borehole spatial morphology and rock formation identification functions to target the fracture evolution of overburden and the detection of gas-rich areas in the overburden during deep coal mining. This equipment can present the previously invisible substances in the coal seams to scientists, thereby enhancing the transparency of gas disaster prevention and control, making the layout of the gas extraction system more handy, and greatly improving the efficiency of gas prevention and control.

The research will benefit the mining industry

Knowledge gained from books is always shallow, and one must practice to truly understand. In Zhao Pengxiang's view, research in the field of gas prevention and control is different from other fields. It is necessary to start from the site to discover and solve problems. Zhao Pengxiang's research experience over the years has been rooted in the front line of the mine. Even before he graduated with a doctorate, he had gone down the mine more than 900 times. After joining the work, he still insisted on this habit. In the past five years, he has gone down the mine 180 to 200 times every year. Although the days underground are very hard, sometimes he stays there for 12 to 13 hours, but he still enjoys it and has no complaints.

Over the years, Zhao Pengxiang has been working tirelessly to carry out more than 30 corporate cooperation projects, and has provided on-site technical guidance on gas disaster prevention and control for high-gas or coal and gas outburst mines in major coal-producing provinces such as Shaanxi, Shanxi, Xinjiang, and Gansu. Zhao Pengxiang believes that coal mine disasters are a dynamic evolution process, and it is not possible to replicate related technologies to other working surfaces by conducting experimental research on a certain coal mine or a certain working face. All technical parameters vary from mine to mine and from face to face.

Under the guidance of this concept, Zhao Pengxiang innovated regional coal mining and disaster prevention technologies by carrying out scientific research project cooperation on coal seam gas extraction and gas control, filled the gap in the prediction method of gas outburst volume in thick and extremely thick inclined fully-mechanized caving working faces, promoted the transformation and industrialization of scientific and technological achievements, promoted scientific and technological progress in the field of coal mine safety, ensured safe and efficient production, and won high praise from management departments and industry experts.

Hard work pays off. Fortunately for Zhao Pengxiang, the severity of gas accidents in my country has decreased year by year in recent years. According to the International Coal Network, in 2022, the number of mine production safety accidents and the number of deaths decreased by 3.4% and 2.4% year-on-year respectively, the number of deaths in major accidents decreased by 12.3% year-on-year, the number of coal mine gas accidents and the number of deaths both decreased by 44% year-on-year, and no rock burst and fire deaths occurred. "Seeing these declining figures, I deeply feel that the work I do is valuable, and I am proud to be a coal mine safety person," said Zhao Pengxiang.

Dedicated to cultivating talents in the coal industry

Only with gratitude can we go far. Along the way, there are many people that Zhao Pengxiang wants to thank for his current achievements. Professor Li Shugang, his graduate tutor, is one of them. Over the years of scientific research, the "three self-principles" (self-centered, self-systematic, and self-justifying) proposed by Professor Li Shugang have had a subtle influence on the formation of Zhao Pengxiang's scientific research thinking. The tutor's rigorous and serious scientific research attitude and style of doing things for decades have further influenced Zhao Pengxiang's scientific research habits, allowing him to be more strict with himself on the road to climbing the peak of scientific research.

During his postdoctoral period, his supervisor Professor Lai Xingping also gave Zhao Pengxiang a lot of help and guidance. In addition, Professor Lin Haifei of the team and Professor Pan Hongyu of the School of Safety Science and Engineering also gave Zhao Pengxiang a lot of pertinent suggestions on the choice of research direction, career planning, research projects, etc. In Zhao Pengxiang's view, they are his mentors and friends, and even more so the guides on his scientific research path. He is lucky to be able to work hand in hand with them on the road of scientific research, and his heart is full of gratitude.

The torch is passed on forever. Under the influence of many mentors and friends, Zhao Pengxiang now hopes to contribute to the cultivation of relevant talents in the coal field. In recent years, with the decrease in the number of college students studying coal majors and the retirement of existing technical talents as they age, the supply of relevant professional talents is unsustainable, and there will be a greater gap in the professional and technical talents needed by coal mining enterprises. Faced with the current situation of the industry, Zhao Pengxiang is deeply worried. How to make students sincerely like research work in this field? Zhao Pengxiang is always thinking about it.

In the process of talent training for many years, Zhao Pengxiang always believed that education should not destroy children's nature. Therefore, he always formulates different training programs according to the different characteristics of different students. "Some students are more extroverted and flexible, so I will let them stay at the research site for a while, and then let them bring what they have learned on the site back to the laboratory; while some students are more introverted, I will let them participate in more laboratory work, and when they have achieved some results in the research, let them submit the relevant results to international conferences." Zhao Pengxiang said. In addition to studying, Zhao Pengxiang also encourages his students to actively participate in competitions such as the National Safety Engineering College Student Innovation Design Competition, and encourages them to exercise their abilities in practice.

As a university teacher, Zhao Pengxiang always sticks to his sense of responsibility, keeps the same work and rest time for many years, and insists on holding morning meetings with graduate students every day, using practical actions to cultivate students' habit of "finishing the work on the same day". He uses scientific guidance to improve the research efficiency of graduate students; through careful training, he cultivates the quality of graduate students to "not find excuses for failure, but only find ways to succeed" to face challenges. It is under the guidance of such teaching ideas of "teaching students in accordance with their aptitude" and "leading by example" that Zhao Pengxiang has trained many outstanding young students in the coal field.

"The golden scenery stretches for thousands of miles, forming a scene that reflects the vicissitudes of life. The weak trees in the sky are rootless, and the lone branches are full of leaves." For many years, the "Poplar Spirit" of Xi'an University of Science and Technology has been inspiring Zhao Pengxiang to continue to take root in scientific research and teaching. In the future, on this ideal land, he will continue to forge ahead and work tirelessly for the development of my country's coal safety cause!