Analyzing kinetics of deformation of boundary rocks of mine workings
S. Nehrii1, S. Sakhno1, I. Sakhno1, Т. Nehrii1
1Donetsk National Technical University, Pokrovsk, Ukraine
Min. miner. depos. 2018, 12(4):115-123
https://doi.org/10.15407/mining12.04.115
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ABSTRACT
Purpose is to analyze nature of rock deformation and to estimate experimentally state of mine workings being supported under the conditions of areas disturbed by coal mining.
Methods. The studies involved field instrumental observations within measuring points equipped with contour benchmarks. Express method was applied to determine height and width of the mine working; typical supported areas were designed; and photographs were taken. The research was conducted in a belt roadway and ventilation raise of western longwall 11 (c18 seam of MM “Pivdennodonbaske No. 1”), and in their connections with the longwall.
Findings. It has been determined that the longwall effect in the mine working, being supported repeatedly, is 80 – 60 m in front of a stope; vertical convergence within the area is more than 1.0 m; floor rise share is almost 76%; and share rate is more than 3 mm/day. It has been specified that local destruction of anchor fitting as well as almost 70% of deformation of frame support is observed within the zone of the longwall affect. It has been identified that potential inrush area from the belt roadway is between supports 3 and 9 of a face zone support; i.e. distance from the seam edge is more than 2.4 m. It has been proved that the use of rigid protective structures is not efficient in the context of soft floor rocks since the protective structures function like dies. Condition of the belt roadway, being constructed and supported behind the longwall, is satisfactory; boundary deformations are within the range of the support flexibility.
Originality. Regularities concerning deformation of boundaries of mine workings under the conditions of unstable wall rocks of c18 seam (MM “Pivdennodonbaske No. 1”), when the mine workings are being constructed and supported behind a stope to be used repeatedly for following longwall, have been determined. Regularities of the process when rocks are forced out into a mine working cavity remained after protective structure, being constructed along a mine working at the boundary of the worked-out area, have been identified as well as regularities of vertical convergence rocks within terminal sites of the longwall.
Practical implications. The findings can be used to develop measures and means for the stability of development mine workings under the conditions of unstable wall rocks and measures to prevent their fall within the tail longwall sites.
Keywords: stability of mine workings, rock mass, deformations, supports, conver
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