You are working on a 1-km highway extension project that requires the construction of a 4-m tall soil embankment with a top width of 15-m and 2H:1V slopes. A borrow-pit (i.e., a place where soils are excavated, to then be placed elsewhere for construction projects) has been identified with e = 0.74, emax = 0.9, emin = 0.5. To avoid excessive road deformations, the soil will be compacted to a relative density of DR = 90% when placed in the embankment. Your boss estimates that extracting 100,000 m^3 of material from the borrow-pit should be enough for this project. Is your boss correct, or is more material than that needed? To decide, answer these questions: a) What volume of soil, as placed, is required to build the embankment? [Tip: draw the embankment] b) What is the void ratio of the material when placed in the embankment? c) What is the relative density of the material in the borrow-pit? d) When soil is extracted from the borrow-pit and then compacted it the embankment, how do Vs, Vv, and VT change? (i.e., do they increase, decrease, or stay the same?) e) For each 1m^3 of soil that is placed in the embankment, how many times more volume must have been extracted from the borrow pit? That is, what is (VT )borrow/(VT )emb?. [Hint: in question D, which parameter remained the same? Use that, and the definition of e, to express (VT )borrow/(VT )emb as a function of eborrow and eemb.] f) Use your work above to answer the original question: is your boss correct? Justify your answer

Principles of Geotechnical Engineering (MindTap Course List)

9th Edition

ISBN:9781305970939

Author:Braja M. Das, Khaled Sobhan

Publisher:Braja M. Das, Khaled Sobhan

Chapter3: Weight–volume Relationships

Section: Chapter Questions

Problem 3.24P

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You are working on a 1-km highway extension project that requires the construction of a 4-m tall soil embankment with a top width of 15-m and 2H:1V slopes. A borrow-pit (i.e., a place where soils are excavated, to then be placed elsewhere for construction projects) has been identified with e = 0.74, emax = 0.9, emin = 0.5. To avoid excessive road deformations, the soil will be compacted to a relative density of DR = 90% when placed in the embankment. Your boss estimates that extracting 100,000 m^3 of material from the borrow-pit should be enough for this project. Is your boss correct, or is more material than that needed? To decide, answer these questions: a) What volume of soil, as placed, is required to build the embankment? [Tip: draw the embankment] b) What is the void ratio of the material when placed in the embankment? c) What is the relative density of the material in the borrow-pit? d) When soil is extracted from the borrow-pit and then compacted it the embankment, how do Vs, Vv, and VT change? (i.e., do they increase, decrease, or stay the same?) e) For each 1m^3 of soil that is placed in the embankment, how many times more volume must have been extracted from the borrow pit? That is, what is (VT )borrow/(VT )emb?. [Hint: in question D, which parameter remained the same? Use that, and the definition of e, to express (VT )borrow/(VT )emb as a function of eborrow and eemb.] f) Use your work above to answer the original question: is your boss correct? Justify your answer

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