Your company has been awarded a contract to carry out excavation work for a proposed Reactor Building near the sea shore. The 80m by 100m rectangular building will consist of a central building surrounded by smaller utility buildings, all founded on a common base raft. You have 65 days to complete the excavation work. This will require excavating over 110,000 cubic meters of earth. To meet this deadline, you will need excavation equipment with a productivity of over 300 cubic yards per hour. You select a backhoe excavator with a 3 cubic meter bucket and haul trucks to transport the earth to the dumping yard 1000 meters away.

1. Reactor Building
Excavation Work

2. . Your company has been awarded to carry out the excavation work for the
proposed
Reactor building (RB) near the sea shore. The area is covered with vegetation
and the
suitable dewatering system shall be provided by others as per the requirement.
A brief
description of RB is given below.
RB is a rectangular building conglomerate (Oriented NS) and measuring 80m
along EW
by 100m along NS in plan at FGL (Finished Ground Level). RB Comprises of a
BG-1
situated centrally, flanked between BG-2 ( on North side ) and BG-3 ( on South
side) as
well as BG -4 (on East side ) and BG-5 (on West side). Remaining three utility
buildings BG-6 (Northeast corner), BG-7 (Southeast Corner), BG-8 (Southwest
Corner)
and BG-9 (Northwest corner) are situated along the diagonals of the BG-1
All the buildings are founded on the common base raft with top of raft at two
different
levels of 2m difference BG-1, 2 &3 at lower level and other buildings & BG-
4,5,6,7,8 &9
at higher level.
The mile stone for starting the raft work by other contractor shall be 120 days
from your
start date. The dumping yard is 1000m from the site. The necessary road work
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3. Site demarcation
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4. Top view of buildings after completion of whole
work
9 2 6
5 1 4
8 3 7
E
N
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5. Sectional elevation of site
Fig. Earth pressure diagram
Dry sand
Density=1542kg/cum
Wet sand
Density:1600kg/cum
Cohesive soil
Coefficient of cohesion C=60KN/sq.m
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6. Assumed schedule of work
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7. Assumptions
 Operator is of average skill with operation factor of
0.80.
 Visibility is good
 Factor of machine transmission is fair
 Rolling resistance is 100lb/ton
 Vegetation is present in the form of trees and bushes
at sea shore with light density
 Trees assumed are:
 Hard woods is less than 25%
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8.  Water table is at 4.5m below ground
level(G.L)
 Soil type is changing below water table and
dredge level of 13m
 Upto water table sand is dry hving bank unit
wt = 1542 kg/cum
 Below W.T soil is wet sandy having unit wt.1600 b
kg/cum
 Below dredge level of 13m soil is cohesive having
coefficient of cohesion 60 kN/sq.m
 Percent swell for dry sand = 15%
 For wet sand = 15%
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9. Reconnaissance
 SURVEYING
 Setting the R.L
 Marking the bounderies
 FENCING THE BOUNDERIES
 Placing cones etc.
 PLACING THE SIGNBOARDS
 ARRANGEMENTS FOR NIGHT LIGHTINGS
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10. TIME REQUIRED
 SURVEYING - 2 DAYS
 FENCING - 1 DAY
 SIGNBOARDS AND NIGHT LIGHTINGS - 1 DAY
 PROCURE EQUIPMENT – 1 DAY
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11. Site cleaning
 Crawler dozers equipped with special clearing
blades are excellent machines for land clearing
 Clearing land operations:
 Removing all vegetation above the ground
 Piling-up the removed materials in windrows
direction
 Selling the vegetation and removed trees
Required productivity= area/time = (14000
+8000)/8*3
= 917sq.m /hr
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12. Outside to center cleaning method
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13. Equipment selection
 Production factor for felling trees(power shift
dozer):
Table 1
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14. Considering 165 hp Dozer
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15. copyright@Amit kumar15

16. Calculation sheet for land cleaning
 Taking 165 hp dozer (Medium dozer) CAT D6R
 Tree count method:
 Time(in min) per acre for
cutting=H(AB+M1N1+M2N2+M3N3+M4N4+DF)
Where,
A=effect of Tree density per acre(<400) on base
time=.70
H=hard wood factor affecting total
time=0.70(Assuming 0 to 25% hardwoods)
B=base time for dozer used per acre depend on size
and capacity for normal efficiency(49.5 mins-
hr)=34.41mins
M=minutes per tree in each diameter range
M1=.70, M2=3.40, M3=6.80, M4=0
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17.  N=no. of trees in each diameter range, from field survey
N1=50, N2=02, N3=0, N4=0
D=0, F=0
 Time in minutes per
acre=0.7(.7*34.41+.7*50+3.4*2+0+0+0)
=46.121 mins
 Increase time by 25% for grubbing operation because
separate provision for grubbing will increase time by
50%
 Time in mins per acre in cutting=1.25*46.121=57.651
mins=60
 Time in mins per acre for piling up the materials in
windrows=B+M1N1+M2N2+M3N3+M4N4+DF
=63.56+.5*50+1*2=90.56 mins
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18.  Total time in clearing=Time in cutting + time in
piling
=area of clearing*(time per acre+
time per acre in
piling)
=5.931(60+114)=1031.994 mins=17.2
hrs
 Days=17.2/8=2.15
=3 days(Matched to schedule)
Under assumed value, so no need to go for other.
 Provide extra time for selling and shifting of trees
etc.copyright@Amit kumar18

19. Haul road construction
 For 850 metres(Providing WBM)
 Stripping of top soil- 2 days
 Dust and other loose materials are cleaned-1 day
 Spreading coarse aggregates-1day
 Compacting laid aggregates- 0.5 day
 Spreading dry screening-1
 Compacting along with water-1
 Spreading of laterite soil/binder material-1
 Compaction using roller-1
 Allow layer to dry overnight
 Patch the hungry spots, holes ,ruts etc and roll those
spots- 1daycopyright@Amit kumar19

20. Material requirements for WBM
 The approximate loose quantity of materials
required for 75mm thick WBM grading-2 for base
coarse layer in cum per 10sq.m are(As per IRC):
 a)coarse aggregate size 63 to 45 mm=.91to 1.07
 b)stone screening type-B, 11.2 mm size=.18 to .21
for base course And 0.14 to 0.17 for surface
course layer
 Now quantity of material for total 1000m x 14m
length:
 Coarse aggregate=1.00*14000/10=1400cum
 Stone screening=.2*1400+ .15*1400=490cum
 Binder material=490cumcopyright@Amit kumar20

21.  Production of roller in compacted cubic yards per
hour=(16.3*W*S*L*efficiency)/n
 Where W=Effective compacted width per roller
pass in feet=7ft.
 S=avg. roller speed in mph=2.5mph(generally for
WBM)
 L=compacted lift thickness in inches=2.953
(75mm)
 N=no. of roller passes required to achieve
required density
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22. Specification of vibratory roller matching with
requirement:
TATA HITACHI BM3
Smooth Drum Vibratory Roller
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23. For base course
•Time taken in spreading of aggregate=1 day
•Production=(16.3*7*2.5*2.953*50/60)/2=350.976ccy/
hr=266.742ccum/hr
•Production in bank cu m/hr=266.742/0.7=381.06b
cum/hr
•Time taken in compaction=1400/381.06=3.674 hrcopyright@Amit kumar23

24. Steel drum
vibratory roller
Steel drum vibratory roller
doing compaction
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25. For binder course:
•screening compaction(two times dry and wet rolling)
Production=(16.3*7*2.5*2.953*50/60)/4=175.488ccy/hr
=133.371cum/hr
•Production in bank cum/hr =133.371/0.83=160.61b cum/hr
•Time taken in compaction=490/160.61=3.051 hr=0.5 day
Time taken to compact screening=2x3.051=6.102hrs=1 day
•Binder material(laterite soil in two layers) compaction is done
in wet
Time=6.1hrs=1day
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26. After 10 working days from the
start of construction of WBM
road
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27. Sheet piling
 Sheet piles are normally used to retain earth.
 Sheet pile used: section
900 mm
300
mm
• By considering 30% extra depth of embedment (for safety)
•Depth of embedment of sheet pile=20m
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28. Determination of depth of
embedment
 Submerged unit wt.=15.696-9.81=5.886kn/sq.m=¥
 Ka=(1-Sinᶲ)/(1+Sinᶲ)=(1-sin30)/(1+sin30)=.333
 Kp=1/ka=3; K’= Kp - Ka=2.67
 Pa
’=active pressure intensity at the dredge line=1/3
*4*1542 + 1/3 *9*(1600-1000) kg/sq.m
=20.169+17.658=37.827kn/sq.m
 a=depth of point of zero pressure below the dredge
line
i.e., a= Pa
’/(¥K’)=37.827/(5.886*2.67)=2.407m
 q at dredge line=15.127*4+17.658*9=219.43kn/sq.m
 Depth of embedment for the cohesive soil below
dredge line is given as,copyright@Amit kumar28

29.  So ,∑ Ray1-D(4C-q)(h+ D/2)=0
=>-
30.254*(1.33+.5)+141.264*4+26.487*5.5+45.525(8.5
+ 2.407/3) – D(4*60-219.43)(8.5+ d/2)=0
=>1078.844-175.78D-10.34D2=0 => D=4.789 m
 Provide 30% extra for safety, D=1.3*4.789=6.226m
 Total length of sheet pile at a
point=13+6.226=19.226m
 Provide depth of embedment 20m with steel sheet
pile.
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30. Contd..
 Required sheet piles =
= 166+133+166+110+250+250
= 1075 sheet piles
Estimated duration =20 days
= 1075/20 = 53 piles /day
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31.  Maximum capacity available is 20 piles /day for
20 m depth
 Taking two vibratory pile driver = 40 piles /day
No. of days= 1075/40
= 26 days
• 6 day more than the allocated time period.
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32. Specification of pile driver
LRB 155
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33. Excavation
 Time allocated to excavation work=65
days(excluding holidays)
 Required productivity of excavator=volume to be
excavated/no.of hours allocated
=(volume of excavated earth from site + volume
of excavated earth for haul road preparation)in
cum/time in hrs
=(109440 + 13650)/(65*8)
=236.712b cum/hr =236.712bcum/hr
0.76bcum/blcy
=311.463blcy/hr
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34.  Available excavators: Back hoe, Front shovel
 We have to do excavation below ground level so
we have selected backhoe for our excavation
purpose.
 Method of excavation used is excavating earth
and moving backward.
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35. copyright@Amit kumar35

36.  Selecting 2.5cy bucket size,
Productivity=277.78bcy/hr
<reqd productivity
 Selecting 3.0 cy bucket size,
 bucket fill factor=100%=1.00(not in percent)
 Efficiency=45min-hr=45/60=.75
 Cycle time=20sec(from table 2)
 Volume correction=1.15
 Hoe productivity=(3600*3*1.00*0.75)/(20*1.150
=352.350bcy/hr
• To dump earth we need hauling equipment
• Select truck of 18.3 cy heaped capacitycopyright@Amit kumar36

37. Hoe ZAXIS 470H
Brand: Tata Hitachi
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38. Specification of truck:
TATA tipper LPK 2518HD9S Engine 239
flywheel horse power
Struck capacity:12cum-=14.9cuyd
Heaped capacity=18.3 cuyd
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39. No. of buckets required to fill truck
=size of truck/volume of one bucket with
correction for fill
=18.3/3=6.1=6 or 7
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40. Truck cycle time
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41. Calculation for production with 6
buckets
 Production ( 6 buckets and 4 trucks) = (4 x 18 x
60 ) / 8.28 = 522 lcy / hr
 Production ( 6 buckets and 5 trucks) = (18 x 60)/
2 = 540 lcy/hr
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42. Calculation for production with 7
buckets
 Production ( 7 buckets and 4 trucks) = (18.3 x
60)/2.33 = 472 lcy/hr
 Production ( 7 buckets and 3 trucks) = (3 x 18.3x
60)/8.5 = 388 lcy/hr
 Case is time constrained:
so selecting maximum value from both cases
Maximum value case: 6 buckets and 5 trucks
Productivity=540lcy/hr
=540 x 0.87=405 bcy/hr
With 45 min-hr efficiency, P=405 x45/60=353 bcy/hr
= 268b cum/ hr
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43.  Time required for excavation=
volume to be excavated /
productivity
= 123090/268 = 460 hr. = 58
days
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44. Planned schedule:
Activity Duration(days
excluding holidays)
Equipments
Site visit 1
Reconnaissance &
sample collection
1
Planning for work
procedure
1
Procurement of
equipment & human
resources
1
Site cleaning 3 Dozer:D6R model 3306T
Sheet piling 26 Pile driver: LRB 155
Haul road 10 Roller: HITACHI BM3
Excavation 58 Hoe: ZAXIS 470H
Truck :TATA tipper LPK
2518HD9S
Site hand over 1
Total=102copyright@Amit kumar44

45. THANK
YOU
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