A Thick Seam Of Coal Is Mined From The Floor 53380

A thick seam of coal is mined from the floor to a height of 13 ft at a depth of 1,450 ft. With reference to the stratigraphic column in the sketch and the rock properties given in Table 5.2, assume L=21 ft, then find:

(a) The safety factor with respect to tension of the immediate roof layer

(b) The layer above

(c) a reasonable bolting plan using the dead weight load approach.

Include (i) bolt length, (ii) nominal diameter, (iii) steel grade, and (iv) spacing Note: Entry width is 21 ft and overburden averages 144pcf.

A thick seam of coal is mined from the floor

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