Stability Mechanism Of Roadway With Soft And Coal-Rock Interbedded Roof And Its Control

The number of roof accidents and the casualties caused by these accidents stay at a high level among coal mining accidents in our country. The occurrence of these accidents has a close relation with roof lithology and its structure and strength as well as the support parameters. Meanwhile, the control mechanism and technology for the stability of roadways with soft and coal-rock interbedded roof are also the hot spots and difficulties for mining personnel.The 16# coal seam is composed of 16-1#,16-2#,16-3#,16-4# and parting in Laoshidan coal mine of Shenhua Wuhai coal group corporation limited. Mining roadway drives along the floor of the16-4# coal seam, whose roof is an interbedded structure composed of thin stratified coal-rock. Compared to general roadways, this roadway generates bigger deformation in its initial stage of excavation and is apt to cave and loss of stability, which pose a great threat to the safe production of coal mines.Thus, it is of great scientific and engineer significance to study the stability mechanism of roadways with soft and coal-rock interbedded roof and its control technology.This paper sets the roadway with soft and coal-rock interbedded roof of the 16# coal seam in Laoshidan coal mine as its research object. Deformation characteristics and fissure evolution law of the air return roadway of 16404 working face has been investigated and surveyed in the field; Field monitoring has been conducted to study the deformation and failure characteristics as well as the evolution law of surrounding rock fissures of haulage roadway in different stages; Characteristics of the roadways with soft and coal-rock interbedded roof are elaborated based on engineer geology and a definition to the connotation of soft and coal-rock interbedded roof is given; Main factors influencing the stability of the roadway are summarized through generalization and analysis; Theoretical analysis is conducted to study the stress state of interbedded roof by using composed rock beam model and mechanism for the loss of stability is revealed; The process of loss of stability of roadways with soft and coal-rock interbedded roof is studied by using finite difference calculation software FLAC2D; deformation and failure law of the adjustment of structural bearing of the roadway is summarized(weakness of structure rigidity-adjustment of stress-stability or loss of stability of the structure); Influences of different roadway sections and bolt intervals as well as the pre-tension of bolt and cable on the stability of roadway surrounding rocks are investigated by using numerical calculation, on these grounds, technology for surrounding rock control of roadways with soft and coal-rock interbedded roof is put forward; Control principles for the management of key process of bolt support are established, based on field technological management idea of "4M1E" method.The research conclusions are applied to field experiment, which yield favorable technological and economic results.