Failure characteristics and control technology for large‐section chamber in compound coal seams—A case study in Tashan Coal Mine

Abstract

The coal production exploited from extra‐thick coal seams accounts for 45% of China's total coal production. With large coal output, the extra‐thick coal seams require that the chamber section be more than 100 m2. In case of parting (the noncoal rock, usually mudstone, sandwiched in the coal seam) in the extra‐thick coal seams, the integrity of the coal seams will be damaged and the large‐section chamber is extremely easy to occur rib spalling and roof leakage, which will increase the chamber's supporting difficulty. To solve such problems, this paper took the electromechanical chamber in Tashan Coal Mine as the engineering background and analyzed the deformation and failure characteristics of this chamber surrounding rocks by the numerical simulation method during the excavation process. The results indicated that the failure areas of surrounding rocks were mainly in partings, chamber ribs, and chamber dome with the failure depths of 15 m, 10 m, and 5 m, respectively. Based on the obtained deformation and failure characteristics, the supporting method of grouting integrated with high‐strength bolts and anchor cables was put forward. The grouting method was firstly used to improve the integrity of the chamber surrounding rocks, and the high‐strength bolts and anchor cables were used for supporting. Then, the supporting parameters of the bolts and anchor cables and the grouting parameters were optimized by the numerical simulation method. The optimized parameters were applied in the electromechanical chamber in Tashan Coal Mine, and the on‐site chamber ribs lateral displacement and roof separation amounts were only 0.018 m and 0.012 m, respectively, indicating that the surrounding rocks were controlled effectively.

Mechanism and Integrated Control of “Rib Spalling: Roof Collapse—Support Instability” Hazard Chains in Steeply Dipping Soft Coal Seams

“…erefore, decreasing the pressure on the coal wall and increasing the shear strength and cohesion of the coal were the main methods for preventing the coal wall from spalling. However, no sensitivity or coal dip analyses were conducted in [34,37], while the findings in this study are corroborated by the above analyses.…”

“…Nevertheless, the increment in the force from the equipment is limited, as is the element strength increment. Wang [34] and Tai et al [37] proposed a plane strain model of coal wall carving and reported that both tensile and shear failures were related to the roof pressure, shear strength, and characteristics of the coal. erefore, decreasing the pressure on the coal wall and increasing the shear strength and cohesion of the coal were the main methods for preventing the coal wall from spalling.…”

“…e available mechanical models [37][38][39] do not apply once the support's load-bearing characteristics are changed. A single support was selected for analysis to facilitate this study, and its loading conditions are depicted in Figure 13.…”

Study on the Development Height of Overburden Water-Flowing Fracture Zone of the Working Face

“…These problems are all related to the deformation and damage of the overburdens caused by the mining of coal resources. Therefore, how to effectively predict the deformation and cracking of the overburdens of the mining coal seams has a very important practical significance for the protection of the overlying aquifers and surface water resources and the prediction of mine water damage accidents [4][5][6].…”

Deformation Mechanism and Stability Control of Roadway Surrounding Rock with Compound Roof: Research and Applications

“…The roof of a compound roof roadway is prone to abscission and subsidence, while both sides are loose coal, therefore, under the pressure of the overlying strata, the interaction between the compound roof and the two sides makes the condition of the surrounding rock worsen, which will lead to instability and even the collapse of the roadway. According to incomplete statistics, over 30% of coal layer roadways in China have compound roofs and this percentage is increasing with the increase of mining depth [7][8][9][10]. The maintenance of roadways with compound roofs has become a choke point for mines in China to extend to deeper areas.…”