Study On The Failure Law And Its Control Technology Of Roof In Extremely Thick Coal Seam Affected By Magmatic Intrusion

study on the failure law and its control technology of roof in extremely thick coal seamaffected by magmatic intrusion with two kinds of sections, and different stress, the locationand size of the igneous, established a total of1700FLAC3D model. The main conclusions areas follows:(1) The results of testing to the original rock strength by international advanced RBSTshowed that: Cohesion, tensile strength and angle of internal friction of the coal affected bymagmatic intrusion were reduced by33.3%,16.2%and75%compared with the coal notaffected.(2) Damage occurs mainly in the area of coal not affected in rectangular roadway withlocal rocks affected by magmatic intrusion, and shows asymmetric distribution whenhorizontal or vertical stress increasing; the damage area first increased and then decreasedwith the igneous away in rectangular roadway with a parallel coalbed affected by magmaticintrusion, and the damage area has a maximum value when the distance is2m from the roofsurface to magmatic intrusion layer; affect almost disappeared on coal due to magmaticintrusion when the distance is greater than4m; the increase of the thickness igneousexacerbated the change width, area of roof damage was "positive Keystone" or "rectangular"under high levels of stress or vertical, and the maximum depth of damage is3.5m.(3) Damage occurs mainly in the area of coal affected in arched roadway with local rocksaffected by magmatic intrusion when horizontal stress increasing, and the failure law is likesto above the law when vertical stress increasing; damage area of roof decreases with theincrease of distance increased from the roof surface to magmatic intrusion layer in archedroadway with a parallel coalbed affected by magmatic intrusion, affect almost disappeared oncoal due to magmatic intrusion when the distance is greater than3m; the extent of damage ismore uniform under high levels of stress or vertical, the larger depth of damage is1.87m invaults and arches.(4) The non-uniformity of situ stress distribution and the non-applicability of routinesupport are the main reasons that caused frequent roof falling in the roadway with local rocksaffected by magmatic intrusion, the support technology of pressure balanced and asymmetricsupporting can solve the problem of roof stability control. Due to the complexity of stress andsurrounding environment, supporting program of the roof with a parallel coalbed affected bymagmatic intrusion should be dynamicly designed.