Under the condition that the working face was directly covered with hard roof, the abrupt breaking of hard roof release significant amount of energy, thus prone to triggering dynamic disasters such as roadway instability or rockburst. This paper based on the engineering background of the Xieqiao Coal Mine's 11,618 working face, a numerical simulation method was put forward to study the dynamic response of roadway under the disturbance of hard roof breaking and proposed an evaluation index I for roadway stability. Research indicates that the elastic energy released during the periodic weighting of the hard roof is higher than that released during the first weighting. Under the dynamic disturbance caused by hard roof breaking, the peak stresses of the roadway was slight decreased, accompanied by a significant increase in the range of stress concentration and plastic zone expansion. Roadway deformation patterns are significantly influenced by hard roof breaking, with noticeable increases in deformation on the roof and right side. During the period of hard roof breaking, the possibility of instability of the roadway increase significantly due to the disturbance caused by the dynamic load. The research results reveal the instability mechanism of roadway under the condition of hard roof, and provide a more reliable basis for evaluating the stability of roadway.
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http://dx.doi.org/10.1038/s41598-024-66376-4 | DOI Listing |
Sci Rep
December 2024
College of Energy and Mining Engineering, Shandong University of Science and Technology, Qingdao, 266590, China.
The Layered Composite Roof Structure (LCRS) is a common bearing structure consisting of multiple layers of rock above a coal seam, and the energy stored in this structure plays an important role in the occurrence of rockburst. Few studies have been conducted on the theoretical modeling of energy storage in LCRS. This study theoretically developed a bending energy storage model for LCRS under three conditions, and the theoretical model was verified by simulation and experimental data.
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November 2024
School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo, 454003, Henan, China.
To address the issues of uncertain pressure relief effectiveness and poor control of surrounding rock caused by the composite nature of the roof strata in the gob-side entry retained (GER), as well as significant changes in strata's thickness and stability differences, this study focuses on the airway of the panel 3113 N in Longtan Coal Mine. Through field detection, theoretical analysis, and on-site applications, a stable mechanical model of the hard roof strata is established, elucidating the factors influencing fracture and instability in composite roof strata. The results indicate that roof stability of the GER depends on the position and ultimate load-bearing capacity of the hard roof strata, which in turn affects roof pressure relief effectiveness.
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November 2024
College of Emergency Management, Nanjing Tech University, Nanjing, 211816, China.
Sensors (Basel)
November 2024
School of Mines, China University of Mining and Technology, Xuzhou 221116, China.
Influenced by various factors such as the complex environment and high key layers in coal mines, hydraulic fracturing technology has gradually become the main means of controlling the hard roof strata to prevent and control rockburst in recent years, which can effectively release the stress on the roof, reduce the intensity of pressure, and ensure the safe and efficient mining of the working face in coal mines. However, the current research on hydraulic fracturing to prevent and control rockburst is mostly limited to optimizing fracturing parameters and monitoring and evaluating fracturing effects, and there are few studies on blank sections, which cannot guarantee the overall prevention and control effect of rockburst, or increase unnecessary construction costs. In this paper, for the directional long borehole staged hydraulic fracturing project, triangular-type blank sections and regular-type blank sections are defined, and the rockburst prevention and control effects of fracturing sections and triangular-type blank sections during fracturing are compared and analyzed by the underground-ground integrated microseismic monitoring technology and transient electromagnetic detection technology, and the rockburst prevention and control effects of fracturing sections and regular-type blank sections during the coal extraction period are compared and analyzed by the underground-ground integrated microseismic monitoring data such as microseismic energy level and frequency as well as the online stress monitoring data.
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September 2024
Department of Industrial Engineering & Management, Ariel University, Ariel 4076414, Israel.
Teleoperation services are expected to operate on-road and often in urban areas. In current teleoperation applications, teleoperators gain a higher viewpoint of the environment from a camera on the vehicle's roof. However, it is unclear how this viewpoint compares to a conventional viewpoint in terms of safety, efficiency, and mental workload.
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