METHOD FOR DETERMINING RANGE OF DANGEROUS ROCK FORMATION OF ROADWAY CEILING

摘要

A method for determining a range of a dangerous rock formation of a roadway ceiling comprises: selecting a region where a tested pulling force limit is less than 1.2 times a designed support body anchoring force; in the selected region, and within a range no more than 0.5 m away from the support body of the pulling test, arranging drilling holes and drilling to obtain a drilling speed per meter, performing comparison to obtain a fastest drilling speed and a slowest drilling speed, calculating a ratio of the drilling speed per meter to the slowest drilling speed, and obtaining a ceiling rock formation range in which the ratio is greater than 2.0; performing detection on a ceiling drill hole using a drill hole imaging apparatus, obtaining a schematic diagram of ceiling crack distribution, and obtaining a ceiling loose material and crack range; and comparing the ceiling loose material and crack range with the ceiling rock formation range in which the ratio is greater than 2.0, so as to determine a ceiling rock formation range having a danger of collapse. The method determines the possibility of a ceiling becoming unstable and collapsing step by step according to three aspects, i.e., a working capacity of a support body, lithologic strength of a ceiling, and looseness and cracking, and has wide coverage, high accuracy, and high operability.