Question

A compacted earthfill embankment of 50,000 m3 final volume is being constructed as part of a motorway project. Material for the embankment is to be taken from a borrow pit, where the soil is found to have the following average properties: bulk density 1.940 Mg/m3 , water content 29.5% and specific gravity 2.69. The soil is mechanically excavated and transported in trucks which carry 6 tonnes of soil each when fully loaded. The soil is dumped on the embankment, spread and broken up, after which a sprinkler adds water until the water content is 38%. The material is mixed by rotary disc and compacted by sheepsfoot rollers until a dry density of 1.290 Mg/m3 is achieved. P.T.O. 3 Using phase diagrams for 1 m3 of fill, determine the following: (a) Dry density, void ratio and degree of saturation of undisturbed material in the borrow area. [10] (b) Volume of excavation needed in the borrow pit. [4] (c) Number of truck loads required to construct the embankment. [3] (d) Volume of water (litres) to be added per truck assuming losses from evaporation are negligible. [3]

Answer 1

We have used phase diagram to show the required data.

Note here that the data given are not practically correct as explained in the solution.