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分析深井煤岩试验断口上矿物、结构、构造等的细观特征,追溯围压对其蠕变损伤机制的影响及调节作用,得到了围压分别为0、10和20 MPa的深井煤岩短时分级加载蠕变试验破坏断口的细观构造,分别对应解理断裂-节理裂隙、沿晶界断裂、沿晶界断裂-穿晶断裂。围压为0 MPa的单轴蠕变试验破坏断口,是煤岩受简单应力环境直接作用的结果,因此,其解理断裂和节理裂隙构造清晰、方向明确、内部新鲜且无夹杂。围压为10 MPa三轴蠕变破坏断口的沿晶界断裂间隙较宽、内部不干净、充填碎屑类夹杂,表明较强环向约束下的晶界较易于克服,且矿物结构以晶粒间的切向运动及力矩作用下的晶粒转动方式调整。围压为20 MPa的三轴蠕变试验,环向强约束使得晶界与晶粒的强度难以克服,最终破坏断口上的沿晶界断裂主要呈现弧形转动,穿晶断裂以剪切位移为主要特征,所以沿晶界断裂构造不太干净、内部充填围压先期作用时原生构造闭合后新产生的少量碎屑类夹杂,穿晶断裂间隙极小、新鲜、干净无夹杂。
The characteristics of minerals, structure and tectonics in the fracture of deep coal are analyzed. The effect of confining pressure on the mechanism of creep damage is traced back. By adjusting the effect of confining pressure on the mechanism of creep damage, When the graded-loading creep test breaks the mesostructure of the fracture, corresponding to the cleavage fracture-joint fracture, along the grain boundary fracture along the grain boundary fracture - transgranular fracture. The uniaxial creep test with a confining pressure of 0 MPa destructs the fracture, which is the result of the coal rock being directly affected by the simple stress environment. Therefore, the cleavage fracture and the joint fissure have a clear structure, clear orientation, and the interior is fresh and free of inclusions. The confining pressure is 10 MPa. Three-axis creep rupture fracture along the grain boundary fracture gap is wide, the internal clean, filled with debris inclusion, indicating that the stronger circumferential restraint of the grain boundary easier to overcome, and the mineral structure of the grain Between the tangential movement and torque under the action of the grain rotation adjustment. Under the confining pressure of 20 MPa, the triaxial creep test shows that the strength of the grain boundaries and grains is hard to be overcome due to the strong circumferential restraint, and the fracture along the grain boundaries at the final failure mainly shows arc rotation. The transgranular fracture has a shear displacement of Therefore, the fault structure along the grain boundary is not very clean, and a small amount of new clastic inclusions generated after the closure of the primary structure during the initial filling of the internal confining pressure is extremely small. The intergranular fracture gap is extremely small and fresh and clean without inclusions.