Question

A tunnel of length L = 130 m, height H = 7.3 m, and width 5.5 m (with a flat roof) is to be constructed at distance d = 47 m beneath the ground. (See the figure.) The tunnel roof is to be supported entirely by square steel columns, each with a cross-sectional area of 893 cm2. The mass of 1.0 cm3 of the ground material is 2.1 g. (a) What is the total weight of the ground material the columns must support? (b) How many columns are needed to keep the compressive stress on each column at one-half its ultimate strength? (a) Number (b) Number Units Units

Answer 1