Abstract: A method for screening a key stratum for overburden separation grouting in a coal mine includes: selecting overall analysis objects based on coal mine planning; conducting a primary screening of the analysis objects based on a scope of a subsidence zone; conducting a secondary screening of the analysis objects based on whether there is an old goaf; determining key stratums for screened-in analysis objects, prioritizing the key stratums based on a number of separation spaces and a range of a separation height, setting a safe height based on a diversion fissure zone, and prioritizing numbers of groutable layers based on a potential separation space and a water resistance of a rock stratum; prioritizing the groutable layers based on a fault impact; and comprehensively analyzing grouting priority levels of the key stratums based on results of the three prioritizations, and grouting separation layers of the key stratums in order of priority.

Abstract: The application relates to the technical field of wiring accessories, in particular to a protective tube. The protective tube includes a tube wall and fluffy warp yarns, wherein the tube wall forms a pipeline for a cable to be threaded therein and includes cross-woven first warp yarns and first weft yarns; the fluffy warp yarns are on an inner surface of the tube wall and are fluffier than the first warp yarns, the fluffy warp yarns are cross-woven with the first weft yarns and form a plurality of intersections with the first weft yarns, and each of the fluffy warp yarns spans a plurality of the first weft yarns between two adjacent intersections. When the protective tube is subjected to external impact, the tube wall with stronger hardness can protect the cable; moreover, the fluffy warp yarn reduce the friction between the protective tube and the cable.

Abstract: The application relates to the technical field of wiring accessories, in particular to a protective tube. The protective tube includes a tube wall and fluffy warp yarns, wherein the tube wall forms a pipeline for a cable to be threaded therein and includes cross-woven first warp yarns and first weft yarns; the fluffy warp yarns are on an inner surface of the tube wall and are fluffier than the first warp yarns, the fluffy warp yarns are cross-woven with the first weft yarns and form a plurality of intersections with the first weft yarns, and each of the fluffy warp yarns spans a plurality of the first weft yarns between two adjacent intersections. When the protective tube is subjected to external impact, the tube wall with stronger hardness can protect the cable; moreover, the fluffy warp yarn reduce the friction between the protective tube and the cable.