Question

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48 A tunnel of length L = 200 m, height H = 72 m, and wide
6.3 m (with a flat roof) is to be constructed at distance d =-
beneath the ground (Fig. 12-49). The tunnel roof is to be supporto
Bolt entirely by square steel columns, each with a cross-sectional
of 960 cm². The mass of 1.0 cm of the ground material is 28
(a) What is the total weight of the ground material the colum
must support? (b) How many columns are needed to keep
compressive stress on each column at one-half its ultima
5.
strength?​

Answer 1

Answer:

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