For the wall shown in Fig. $1.$ Calculate a$)$ the factors of safety with respect to

overturning and sliding and b$)$ compute and draw the soil contact pressure. Assume

the coefficient of friction at the base is $0\mathrm{.}45.$

A reinforced earth retaining wall is to be $30$ ft high. Backfill: unit weight, $120l\frac{b}{f}{t}^3,$

for the soil friction angle, $=34.$ Reinforcement: vertical spacing, $2\mathrm{.}5$ ft $,$

horizontal spacing, $3\mathrm{.}0$ ft $,$ width of reinforcement $=4\mathrm{.}75in.,f_y=38,000l\frac{b}{i}{n}^2,$

angle of friction between soil and reinforcement $=25,$ factor of safety against tie

pullout $=3,$ and factor of safety against tie breaking $=3.$ Determine:

a$.$ The required thickness of ties

b$.$ The required minimum length of ties