Decided to use dump trucks to excavate and haul the fill mat

Decided to use dump trucks to excavate and haul the fill material. The empty weight of a truck is 40 tons. The distance between the borrow and the construction sites is 3.5 miles, and the road has an average uphill grade of 3.5% when travelling from the borrow site to the construction site. When fully loaded, the truck can carry 23 tons of fill material (LCY). You have investigated that the average tire penetration when the truck is loaded in 1.5 inches.

a. What is the grade resistance force against a fully loaded truck?

b. What is the rolling resistance force against a fully loaded truck?

c. What is the effective grade (%) against fully loaded truck?

d. What is the total resistance force against the truck when returning from the construction site to the borrow site?

I

Solution

Solution:-

(a) Grade resistance = loaded truck weight(t) x grade resistance factor(lbs/t)

                                    = 63 x 70 = 4410 lbs Answer

Where grade resistance factor = 20 x (grade %) = 20 x 3.5 = 70 lbs/ton

(b) Rolling resistance factor = 40 + ( 30 x penetration of tire )

                                                  = 40 +( 30 x 1.5) = 85 lbs/ton

       Rolling resistance = loaded truck weight x rolling resistance factor

                                       = 63 x 85 = 5355 lbs   Answer

(c) Effective grade (%) under fully loaded truck = grade (%) + rolling resistance factor / 20

= 3.5 + 85/20

= 7.75 %   Answer

(d) Total resistance force against the empty truck = Rolling resistance + grade resistance

= 40 x 40 + 40 x 70

= 1600 + 2800 = 4400 lbs    Answer

Where rolling resistance factor for empty truck = 40 lbs/ton