Field and numerical investigation on roof failure and fracture control of thick coal seam roadway

An, Yanpei; Zhang, Nong; Zhao, Yuemin; Xie, Zhengzheng

doi:10.1016/j.engfailanal.2021.105594

Cited by 37 publications

(14 citation statements)

References 34 publications

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“…In the meanwhile, the fragmentation of the coal is more developed due to the influences of tectonic stress, which explains the differences in mechanical properties between the coal and the rock mass. According to a comprehensive analysis based on literature 7 , 8 , the roadway with coal-rock composite roof is typical of the following deformation characteristics: ① The coal seam differs significantly from the rock stratum in properties, accompanied by a higher possibility of the separation and collapse of the coal seam from the rock stratum after roadway excavation is started. ② Since cross cracks are widely distributed in the coal, the deformation of the surrounding rocks denotes the propagation of the cracks, which will easily lead to the embrittlement and fragmentation of the coal seam.…”

Section: Introductionmentioning

confidence: 99%

Model experiment research on HPTL anchoring technology for coal-rock composite roof in deep roadway

Xie

Zhang

et al. 2023

Sci Rep

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Since the western region of China, which is typical of extraordinary resource endowments, has gradually emerged as the major mining zone in China, the mining of thick coal seams and roadways with coal-rock composite roof have become more and more common in this region. However, it is extremely difficult to realize safe and effective maintenance and control of such roadways due to the differences in natural endowments of coal-rock masses. With the roadway with coal-rock composite roof of Hulusu Coal Mine in western China as the engineering background, experiment research on large-scale similarity model was conducted through comprehensive measures such as the pneumatic loading system, the surrounding rock stress monitoring system, the roadway deformation monitoring system, the bolt load monitoring system, and the displacement field monitoring system in this paper. According to the results of the experiment, the control effects of the three support systems on the roadway with coal-rock composite roof were significantly different. When the single support of short anchor bolts was applied, the comparatively low initial anchor-hold failed to constrain the initial micro deformation of the roof. Consequently, wide-range fractures of the roof were triggered at a loading pressure of 0.8 MPa. In the meanwhile, the deep surrounding rocks witnessed a downward inflection point in stress, accompanied by the possibility of the collapse of the thin-layer anchorage zone at any time. As for the support combining both short anchor bolts and long anchor cables, though a reinforced effect on the bolt anchorage zone could be achieved with the help of the cables, the active reinforcement capacity of the bolt was limited. The bolt anchorage zone was the first to be damaged at a loading pressure of 0.9 MPa, which would subsequently affect the effective bearing capacity of the deep surrounding rocks. In the application of the single support of high-strength long anchor bolts, the long bolts with high pre-tightening force were able to lock multiple groups of coal-rock strata to form a thick-layer anchorage bearing structure capable of withstanding a load as high as 1.0 MPa. The crash and collapse of the coal wall eventually caused the subsidence of the roof. Based on the intense dynamic load experiment and the feedbacks of engineering application outcomes in the field, it was concluded that the high-pretension thick-layer (HPTL) anchoring technology can effectively constrain the deformation of roadways with coal-rock composite roof with favorable application outcomes.

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Section: Introductionmentioning

confidence: 99%

Model experiment research on HPTL anchoring technology for coal-rock composite roof in deep roadway

Xie

Zhang

et al. 2023

Sci Rep

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“…At present, relevant scholars have carried out a lot of research work on the stability and control technology of the roof-rib bearing system and have achieved fruitful research results. An et al took the thick-coal-roof roadways as the research object, studied the evolution law of the roof failure area under the condition of insufcient support, and proposed an improved support with thick anchoring structure and roof reinforcement, which efectively reduced the damage height of the thick coal roof [5]. Bai et al studied the process of progressive roof failure in a wide coal roadway from waterrich roofs based on the UDEC method.…”

Section: Introductionmentioning

confidence: 99%

Stability Analysis of Roof and Rib and Source Control Countermeasures of Ultrahigh Roadway in Deep Coal Mine

Zhu

Hua

2023

Shock and Vibration

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Driven by the high original rock stress and engineering disturbance, the ultrahigh roadways of about 7∼8 m appear in the deep coal mine. Based on the field measured data, the stability in different zones of roof and rib is divided. From shallow to deep, the roof forms potential leakage and falling zone, metastable zone, and stable zone, and the coal rib forms potential spalling zone, crack developed zone, and transition zone. Based on the theory of transverse isotropy, the mechanical analysis model of layered roof is established, the real stress state at any point of layered roof is deduced, the roof failure criterion is constructed, and the theoretical solution of the failure depth of layered roof is obtained. The mechanical model of pillar bar of the splitting coal body in the potential spalling zone is established, and the deflection deformation expression of the pillar bar is derived. In view of the deformation and failure characteristics of the roof and rib, this paper puts forward the cooperative integrated support technology based on high-strength prestressed cables and deep-shallow hole grouting, which effectively reduce the hidden danger of roof falling and eliminate the formation of ultrahigh roadway from the source.

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“…As a common phenomenon, after excavating deep underground openings, the equilibrium state of the original rock mass is broken. With the redistribution of high ground stress, cracks evolution will occur in and outside the short bolts anchorage zone and will tend to develop in a large scope [5], which increases the difficulty of roof control in the deep roadway [6]. During roadway driving in deep coal measures, micro damage and irreversible plastic zones occur [7], and roof fall will happen progressively, which stops the operation of mining machines and poses a big threat to human security.…”

Section: Introductionmentioning

confidence: 99%

Damage Data Analysis of Deep Coal Roadway Roof and Application of Long Anchorage and Zone Linkage Support Technology

Wang

Zhang

et al. 2022

Sustainability

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China’s energy structure mainly depends on coal resources, which will still play the dominant role in economic development in the future. With the mining depth increasing, the deep roadway construction will be exposed to a complex stress environment, increasing the difficulty of roof control and further hindering the mining activities. The problem of deep roadway excavation causing significant fracture scope of surrounding rock in and outside the anchorage zone has attracted much attention. For the large crack scope existing in the roadway roof of deep underground openings, this paper focuses on the exploration of upgrading the support system. In order to solve this problem, we investigated the zone damage of the roadway roof with the discrete element model using the UDEC trigon method and damage quantified evaluation with data analysis. The long anchorage and zone linkage support technology was proposed based on the damage control effect of varying lengths of supporting bolts. The purpose of extending the length of bolts is to link the more severely damaged rock mass in the shallow part to the minimum damaged part in the deep place, aiming to form the thick anchor zone to mobilize the rock mass in each zone to participate and bear the load together. Furthermore, the onsite application of long anchorage and zone linkage technology gained good control effects in the selected typical roadway with different geological conditions. The results show obvious resistance in cross-section shrinkage, integrity maintenance, and minimization of crack scope in the roadway roof. The promotion of long anchorage zone linkage technology can help the mine with similar situations uplift the efficiency of working and guarantee the safety of miners during mine service life in the deep coal roadway.

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Field and numerical investigation on roof failure and fracture control of thick coal seam roadway

Cited by 37 publications

References 34 publications

Model experiment research on HPTL anchoring technology for coal-rock composite roof in deep roadway

Model experiment research on HPTL anchoring technology for coal-rock composite roof in deep roadway

Stability Analysis of Roof and Rib and Source Control Countermeasures of Ultrahigh Roadway in Deep Coal Mine

Damage Data Analysis of Deep Coal Roadway Roof and Application of Long Anchorage and Zone Linkage Support Technology

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