So the minimal uncontrolled roof-fall span, displacement Angle and caving Angle are studied by similarity simulation.
借助相似模拟试验，研究了顶板自然垮落的最小跨度、移动角和垮落角。
So the minimal uncontrolled roof-fall span, displacement Angle and caving Angle are studied by similarity simulation.
借助相似模拟试验，研究了顶板自然垮落的最小跨度、移动角和垮落角。
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