老人病学
发表于 2025-3-25 04:40:13
Behaviour of Coal Measures Rocks,t, in an engineering sense, an easily definable state and can mean either reduction in strength or excessive deformation. For instance, stronger rocks, or rocks at low confining pressures will tend to fail through fracturing, with release of energy and dilation, accompanied by a reduction in load-be
entitle
发表于 2025-3-25 08:10:51
Design of Rooms and Pillars, of a room and pillar mine layout, or can be designed as a support element in a different type of mine layout. In Europe, these pillars tend to be used between longwall faces to protect access roads, while in the United States the multiple entry system utilizes two or more support pillars.
牵索
发表于 2025-3-25 13:01:52
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骂人有污点
发表于 2025-3-25 19:51:24
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斜谷
发表于 2025-3-25 22:59:13
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Barter
发表于 2025-3-26 00:53:52
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直觉好
发表于 2025-3-26 05:46:23
Book 1985 by the deformation characteristics of the rocks which surround them. The work is based on observatiollB by many engineers working for the National Coal Board‘s Mining Research and Development Establishment, and by research associates and postgraduate students at the University of Newcastle upon Tyn
表脸
发表于 2025-3-26 12:15:41
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Intersect
发表于 2025-3-26 13:16:00
R. D’Amelio,O. Cosivi,D. L. Heymannaring capacity from a peak to a residual strength. In coal mining the extreme manifestations of this type of failure will be associated with caving of strong sandstone beds overlying the coal seam during longwall mining, or possibly with collapse of isolated coal pillars in longwall, shortwall or room and pillar mining.
probate
发表于 2025-3-26 18:43:11
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