Experimental study on the characteristics of spatiotemporal evolution of overburden deformation and failure in fully mechanized caving face
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Abstract
The deformation and failure test of the overlying strata during the roof collapse of the working face in the goaf is carried out by a similar simulation experiment method.A CCD camera is used to construct an experimental image data acquisition system, and digital speckle correlation methods are used to analyze the displacement field and collapse angle of the overlying strata, and the evolution of cracks, displacement evolution and skewness characteristics of the overlying strata collapsed area are studied.The research results show that the angle of the overburden strata angle changes continuously with the shape of the collapsed area, the height of the collapse gradually decreases until it becomes stable, and the area of the collapse gradually increases until it becomes stable.In the vertical direction, the collapse zone of the overburden layer exhibits a wide "W" type settlement, and the fissure zone and the curved subsidence zone exhibit a "V" type settlement; in the horizontal direction, the upper and lower overburden strata move to both sides, and the upper strata move to the middle, which will cause frictional sliding between the rock layers and produce bending moments on the unexcavated areas and coal pillars on both sides.The roof of the working face is skewed after lagging behind.The fall angle on the side of the cut is greater than that on the mining side, a rock shift angle is formed on the mining side, and the settlement curve is slow.According to the actual engineering background, the impact area of the surface collapse is calculated, which is coal mine mining has provided the necessary basis for the assessment of the impact range and degree of overlying rock strata and subsequent governance of mined-out areas.
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