4 A set of dual tires spaced 375 inches centertocenter carry

(4) A set of dual tires spaced 37.5 inches center-to-center carry 45,000 lbs. each with a tire pressure uivalent single wheel u pavements 12, 18, and 24 inches depth. Comment on the effect of depth on the equivalency determinations [Hint: See Chapter 6 for ESWL calculations].

Solution

Solution:-

Given

Wheel load = 45000 lb

Radius of wheel(a) = (P/(p)) = (45000/(*125)) =10.7 inch

d = S – 2*a

     = 37.5 – 2*10.7 = 16.1 inch

When depth z = 12 inch

log₁₀ESWL = log₁₀P +0.301*log₁₀(z/(d/2))/(log₁₀(2S/(d/2)))

                   = log₁₀45000 + 0.301log₁₀(12/(16.1/2))/(log₁₀(2*37.5/(16.1/2)))

                  = 4.707

ESWL = antilog(4.707)

           = 50933.08 pound   Answer

When depth z = 18 inch

log(ESWL) = log45000 + 0.301log(18/(16.1/2))/(log(2*37.5/(16.1/2)))

                  = 4.76

ESWL = 57543.9 pound Answer  

When z = 24 inch

Log(ESWL) = log(45000) + 0.301log(24/(16.1/2))/(log(2*37.5/(16.1/2)))

                   = 4.8005

ESWL = 63168.41 pound ANSWER

When depth increases, then equivalent single wheel load also increases.