For Problem $13\mathrm{.}20,$ determine approximate dimensions

of retaining walls, check safety factors against overturning and slid$-$

ing, and calculate soil pressures for the wall shown. Also determine

the required stem thickness at their bases and select vertical rein$-$

forcing there, using $f_y=60,000,f_c^{\text{'}}=3000,q_a=5000psf,$

$=$ approximately $0\mathrm{.}18\frac{f_c^{\text{'}}}{f_y},$ angle of internal friction $=33{40}^{\text{'}},$

and coefficient of sliding friction $($concrete on soil$)=0\mathrm{.}45.$

Soil weight $=100l\frac{b}{f}{t}^3$ and concrete weight $=150l\frac{b}{f}{t}^3.$ h$=22$ft There is a surcharge of $200$psf$.$