Question

Q2. The figure below shows the extreme dimensions for excavation for a basement construction which is 10 ft. outwards from the basement walls. The site has a limited space for storing the excavated material hence it has to be hauled to a different location. Using the higher end of the swell percentage for dense clay calculate the amount of soil to be hauled and the loads required if one dump truck can haul 21 cu. ft. of soil. Also, compute the loads to back fill the soil after basement construction if the same dump truck is utilized with a shrinkage percentage of 90% and the depth of excavation is 12 ft. 14' 52" -14- - 12" 12 48' 48' 80

Answer 1

Hi,

Solution as follows:

Part 1) Volume of Soil to be hauled and number of haul truck loads

Given Data:

· Capacity of each haul truck = 21 cy

· Depth of excavation = 12 ft

· [Assume swell factor = 1.25]

Since the work site does not have enough space, the total excavation quantity needs to be hauled off.

Since the above quantity is in bank state, it is denoted as bcy.

In earth work operations, soil to be hauled is measured in loose state and truck capacity is also given in loose cubic yards (LCY).

Quantity of earth to be hauled off = BCY x Swell factor = 1984 x 1.25 = 2480 LCY

Number of truck loads = LCY / Capacity = 2480/ 21 = 118.1 say 119 loads

Part 2) Volume of Soil to be back filled and number of haul truck loads:

Given Data:

· Capacity of each haul truck = 21 cy

· Depth of excavation = 12 ft

· Shrinkage factor = 90% = 0.9

· [Assume swell factor = 1.25]

Back fill volume = Excavation volume – volume of basement = 1984 – 917.33 = 1066.67 cy

Since the above quantity is in compacted state, it is denoted as ccy.

In earth work operations, soil to be hauled is measured in loose state and truck capacity is also given in loose cubic yards (LCY). However the back fill volume is in compacted cubic yards (CCY). To convert CCY to LCY, we need to apply swell and shrinkage factor.

Number of loads = LCY / Capacity = 1481.48/ 21 = 70.55 say 71 loads