PECivilExam.com Breadth Exam (morning session): This practice exam contains 40 mixed questions and answers, each set being from all five areas of civil engineering:
PROBLEM (Earth work) An embankment cross section is shown in the Figure, the soil in the embankment has to be compacted, and the soil dry unit weight is106 lb/ft3, moisture content is12.5%. The borrowed soil will be brought in a 10 cubic yard truck at haul with a void ratio of 0.7 and a moisture content of 10%. The borrowed site soil has a void ratio of 1.0 & specific gravities, Gs=2.67. What will be the number of haul truck loads for 100 ft length of embankment construction? a. b. c. d.
314 numbers of trucks 414 numbers of trucks 360 numbers of trucks 276 numbers of trucks
1. Solution: Vol. of Embankment per 100 ft length= {(24+74)/2} x 16 x 100=78400 ft 3 Moist unit weight of truck γ =(1+w)Gs γw /(1+e)=2.67x62.4(1+0.1)/(1+.70)=107.80 lb/ft 3 The dry unit weight of truck γd = γ /(1+w)=107.8)/(1+.1)=98.0 lb/ft 3 Weight of dry soil per truck= 10 x 27 x 98=26460 lb Dry weight of Embankment compacted soil= 78400 x 106=8310400 lb Number of truck= 8310400/26460=314 number of trucks Correct Solution is (a)
PROBLEM (Soil Classification) A soil sample has been given in the following value. What is the AASHTO soil classification? Sieve No-10 No- 4 No-200 L.L PI a. b. c. d.
9.
Passing 100% 80% 37% 44 12
A-7-6 A-7-5 A-7 A-4
Solution: Soil passing #200 sieves is 37% which is greater than 35%; therefore it is a silty clay soil. So it falls under A-7 on AASHTO classification chart. Also, PI=12<(LL-30=14), Therefore, it is A-7-5. Correct Solution is (b)
Solution: L=30 ft WLL=200 #/ft WDL=300 #/ft Considering, DL factor=1.4 and LL factor=1.7 WuDL= 1.4 x 300=420.00 #/ft WuLL= 1.7 x 200 =340.00 #/ft Moment for uniformly Dead Load, MD= WuDLL2/8 Moment for triangular live Load, ML=0.0642 WuLL L2 Mu= WuDLL2/8 + 0.0642 WuLL L2= 47250.00+19645.20= 66895.20#-ft = 66.90Kip-ft Correct Solution is (a)
