Stability Control of Underground Openings Under High-Stress and Deep Mining Environments

1. Introduction

Mining engineering plays a significant role in current society [1,2,3]. In fact, coal mining engineering significantly contributes to the development of the social economy [4].

Since raw coal production is abundant, mining depths are becoming larger. For in situ stress in rock masses before mining, when the buried depth becomes larger, in situ stress increases significantly, including vertical stress and horizontal stress. Under high in situ stress conditions, strata deformation and failure behavior become more apparent. For example, the deformation of roadways and chambers becomes larger. In certain cases, roof collapsing may occur. This poses a high risk to underground operators and equipment. Moreover, since the mining depth becomes larger, elastic energy accumulated in rock strata becomes higher. When accumulated high elastic energy releases suddenly, rock burst disasters may occur [5,6]. This creates more risks to the safety of underground staff [7].

To overcome the above issues, rock reinforcement and rock support methods should be used [8,9,10,11,12]. Although much research has been conducted to study rock reinforcement mechanisms and rock support mechanisms [13,14], the load transfer process between rock reinforcement bolts, rock support instruments and rock masses has not been fully understood.

Therefore, it is quite necessary to further study the rock reinforcement mechanism and rock support mechanism of bolts, cables, tendons, mesh and lining [15,16,17]. As such, we established this Special Issue named “Stability Control of Underground Openings Under High-Stress and Deep Mining Environments”. For this Special Issue, we aim at attracting researchers and engineers to submit their latest research regarding stability control of underground openings, especially in a deep mining environment. Through reading these published academic papers, readers can further and better understand the latest stability control methods and corresponding mechanisms in ground control areas in deep mining engineering.

2. An Overview of Published Articles

This Special Issue received 27 academic papers. Among them, 12 were successfully published. These academic papers are from China and Poland, and their topics are related to roadway reinforcement, strata control of roadways that are near gobs, the adaptability of anchor support, rock burst issues and rock failure around roadways. These academic papers used different methods to reveal rock reinforcement mechanisms and rock failure mechanisms, including in situ observations, numerical simulation, laboratory experimental tests and in situ engineering practice. For example, Zhou, et al. [18] indicated that under thick and hard roofs, the stress environment of roadways that are near gobs became more complicated. This even induced coal bursts in underground mining engineering. To solve this issue, they used numerical simulation methods to analyze the stress–energy evolution law of working faces, coal pillars and rock masses around roadways. Their results are valuable for readers to understand coal burst mechanisms in similar geological conditions. Wang et al. [19] indicated that layered composite roofs were composed of developed bedding fissures. This may lead to severe deformation and the failure of rock bolts in roadway roofs. Based on this background, they conducted in situ observation and found that minor shear deformation existed in rock bolts at the center of roadway roofs. Significant shear deformation existed in rock bolts in roof corners and lateral deformation was more than 176 mm. Then, numerical simulation was conducted with the commercial software FLAC^3D. They found that the main factors affecting rock bolt deformation included the strength of geological joints and the strength of the rock mass around openings. Their research is beneficial for understanding instability mechanisms and supporting the treatment of layered composite roofs. Pytel et al. [20] indicated that maintaining the stability of underground openings buried at a great depth was challenging. They developed a simplified analytical method for ductile ground support design in underground mining. Their proposed algorithm made it possible to conduct tracking of the rock burst phenomenon. This information is valuable when designing support parameters for underground openings. To sum up, these published academic papers in this Special Issue will help readers to better understand the interaction between rock masses and rock reinforcement instruments.

3. Conclusions

The stability of underground openings is significant in maintaining the normal operation of underground mines. As mining depth increases, the difficulty of maintaining underground opening stability becomes larger. Researchers have proposed various methods, instruments and facilities to guarantee the stability of underground openings in a deep mining environment. However, there are still a number of challenging issues. Therefore, it is quite necessary to continue studying in this research area. With the development of fundamental research, it is expected that the stability issues of underground openings can be minimized to a great extent.