Chapter 15, Problem 15.5PFS

Part 3: Problem-Solving. Solve the following problems. Show all calculations. 1. A retaining wall 5.80m high supports soil that has the following properties: Unit weight = 17.3 kN/m³ Angle of internal friction = 26 deg. Cohesion = 14.5 kPa a) Calculate the normal pressure acting at the back of the wall assuming no tensile crack occurs in the soil. b) Find the location of the tensile crack measured from the surface of horizontal backfill. c) Determine the active pressure acting on the wall in tensile crack occurs in the soil. 2. The soil material is supported by a retaining wall to a height of 6m. The unit weight of the soil is 16 kN/m³ and the angle of internal friction is 29 deg. Assume the soil is cohesionless. a) Determine the earth pressure on the wall. b) Find the total active pressure if surcharge of 14 kPa is applied on the surface of horizontal backfill. c) Locate the position of the total pressure from the bottom.

Question 3 (20 points): The traffic volume on a 2-lane highway is 1600 veh/hr in each direction Page 3 of 6 with a density of 20 veh/mi. A large dump truck enters the traffic stream from an adjacent construction site at 20 mph and carries on this way for 2 miles before turning off to the dump site. Because flow is so high in the opposite direction, no one can pass the truck. As a result, traffic back up behind the truck at four times the density (i.e., 4x20 = 80 veh/mi) at a volume of 1000 veh/hr. How many vehicles get caught in the traffic congestion before the truck exits the highway?

How can construction project managers find a balance between speeding up schedules and the risks of making more mistakes and needing rework, especially when using methods like fast tracking?