1. REPORT
ON
CONSTRUCTION OF HIGH
LEVEL BRIDGE
BY:
CH.HARSHA VARDHAN(1210211216)
K.MANIDEEP (1210211227)
G.MANIKANTA REDDY(1210211224)
T.ABHINAY (1210211258)

2. CONTENTS:
Acknowledgement
Introduction
Alignment
Well components
Well parameters
Reinforcement
Dredging
Tilt and shift
Methods and corrections
Problems

3. ACKNOWLEDGEMENT
We are obliged to Sri.Ranavittal ,EE for giving us the opportunity to
undergo training at site in Anantapur district.
We are thankful to Sri.D.Madhusudana Reddy ,DEE, PR, for properly
guiding us throughout our training period.
We are grateful to Sri.V.Nagasekhara ,AEE, PR, for explaining various
concepts and clarifying all our doubts very patiently.
We would also like to thank Sri.Venu Prasad, site engineer, for helping
us out regarding technical doubts we had.
At last, but not the least we would also like to thank our HOD,
Mr.M.Ramesh for allowing us to undergo training.

4. INTRODUCTION
Well foundations are quite appropriate foundations for alluvial soils in
rivers and creeks where maximum depth of scour can be quite large. In
India technology of well foundation for design and construction is quite
well developed. Still there are situations where serious problems are
encountered at site during construction of well foundations.
In the Indian subcontinent there are many rivers where the depth of
alluvial deposits is very high and the scour around the pier foundations
can be very deep if the piers are located within the active channel of
river. For such condition well foundation is a very appropriate type of
foundation.
In India the technology for the design and construction of well
foundation is quite advanced. In all rivers, including large rivers with
torrential flow of water currents, well foundations were provided. In
the foundations of Howrah Bridge in Kolkata giant monoliths were
provided. In Second Hoogly Bridge also in Kolkata with one of the
longest span cable stayed bridges in the world having the central span
of 457 m being same as that of Howrah Bridge, an ingenius solution was
adopted. Instead of a monolith for the foundation of each tower of the
cable stay bridge, 2 well foundations up to 23 m dia were placed side by
side at 30 m center and interconnected by a 14 m deep beam. This
solution was construction-wise easier and more controllable and
quantity of material used was much less. These wells were constructed
purely by gravity sinking method.

5. PROJECT BREIFING:
 This bridge forms a part of a bye-pass project near P.kothapalli.
 The project is undertaken by Panchayat raj engineering
department of Government of Andhra pradesh.
 Total cost of the bridge over penna river is 14 crs.
 The contract is given to the company on MNT Grant.
Length 453.33m
Lanes 2
Spans 29
Formation level +340.014
High flood level +336.553

6. Alignment:
 Alignment of the bridge passes through :
Penna river between p.kothapalli and katrimala village
 Alignment crosses river at an angle therefore it is a Skew
alignment

7. Height of Bridge:
 Bridge is high level bridge i.e. formation level is above H.F.L.
 Height of bridge is determined by examining the clearance of
bridge over highway.
 Road level =340.014
 depth of slab = 1.7 m
 Actual formation level= m

8. WellComponents:
 Cutting edge
 Well curb
 Well steining
 Bottom plug
 Sand fill
 Top plug
 Well cap

9. Cutting edge:
•Cutting edge is the lower most part of a well it is the part which cuts
through the earth.
•The mild steel cutting edge shall be made from structural steel
sections.
• The cutting edge shall weigh not less than 40 kg per meter length and
be properly anchored into the well curb
• Sections are bent into shape by cold bending no heating is done.
Sections are curved and welded to form Cutting Edge.

11. Well curb:
•Well curb is a structure with outer wall of curb being straight and
inner at an appropriate angle which is fabricated over cutting edge.
•The internal angle of curb can be kept between 300
to 370
.
•It serves the purpose of transferring load from steining to bottom
plug.
•Thickness of well curb is 75mm more than that of steining to prevent
tilts. A fabricated well curb set atop wooden planks

12. Well steining:
 It is the longest part of well and it transfers load from well cap to
the well curb at desired depth.
 Track of length is taken by marking wells on 4 sides by gauges.
Steining is built in lifts of 1.5 m and each lift is aligned with
previous one.
 As per IRC 78:2001.The amount of vertical reinforcement
provided should not be less than .2% of cross sectional area of
steining.
 At the inner face reinforcement must not be less than .06% of
area.
 Transverse reinforcement must not be less than .04% of
volume/unit length of steining.

13. Bottom plug:
 Transfers the load of structure from well to the ground. It is cast
under water after the final depth of well is reached. No
reinforcement is provided. The mix should have min. cement
content of 330Kg/m3
Sand filling:
 Sand filling shall commence after a period of 3 days of laying of
bottom plug. It helps in increasing the weight of the foundation
which provides more stability to the structure. It also counteracts
buoyant force of water.
Intermediate plug :
 The function of the plug is to keep the sand filling sandwiched &
undisturbed. The concrete used for intermediate plugging is also
M25.
Top plug :
 After filling sand up to the required level a plug of concrete is
provided over it as shown on the drawing. It at least serves as a
shuttering for laying well cap.
Well cap:
 It is needed to transfer the loads and moments from the pier to
the well or wells below. It is designed as two way slab.

14. WELL PARAMETERS
Total numbers of wells to be sunk 28
Grade of concrete used for well
curb and steining
M30
Grade of concrete used for bottom
and top plugging
M15
Type of cement used OPC
Grade of steel used for
reinforcement
FE415
Thickness of cutting edge 10mm
Depth of the wells below ground: pier type-1 :8.6m
pier type-2:11m
Pier type-3:6.6m
Pier type-4:6.5m
Height of well curb: 1.5m
Thickness of well steining: 0.75m

15. Reinforcement
 Reinforcement in curb(1.5m)(Bottom)
1. Dia of bars used = 12/16mm
2. Spacing of curb rods = 0.15m
3. Total curb rods = 140
4. 12mm links are provided to the curb rod
5. centre to centre distance between curbs = 16.79m
6. For steining , an offset of 3inches is provided
7. curb defines the shape of frustrum
8. M20 concrete is used
 Steining ( above curb) [1.5m internal]
1. Dia of horizontal bars used is 12mm
2. Spacing of bars = 0.22m
3. Dia of Vertical bars=16mm @220mm centre to centre
4. Total no of bars = 7
5. No of vertical bars in steining = 95
6. No of horizontal bars in steining = 8

17. CONSTRUCTION OF WELL
Setting of well curb
Sinking of well
Bottom plugging
Sand filling
Closing of top by well cap

18. Setting of well curb
 The center of the well is marked accurately with help of
theodolite.
 Cutting edge is placed on the wooden sleepers such that center of
cutting edge coincide with the marked center.
 Reinforcements and formwork for curb is fabricated on the
cutting edge and concreting is done.
 After curing of well curb is complete the wooden slippers below
the curb are removed by making soil below them diluted by water
and is allowed to sink under its own weight.

19. Sinking of Well Fabrication of Formwork
Fabrication:
 The form work for casting are supported on the channels bolted
with steining on both sides.
 As per design lap is provided after every fourth reinforcement at
same section.
Concreting:
 Concreting is done by pumping the concrete to the mould by
concrete pump.
 The concrete is placed in 400mm thick layers along with
continuous vibrations.
 On average about 23 m3
of concrete is needed for casting of one
lift.

20. Dredging :
 In order to sink the well, continuous dredging is done.
 Soil is excavated from the dredge hole inside the well.
 The dredging operation is performed evenly along the hole
circular hole

21. Methods to promote sinking
Kentledge :Total of 125 concrete cubes of 1m3 in size are made for
kentledge loading which is approximately equal to 25t × 125.
Chiseling: When the boulders are very firmly cemented then chiselling
is done. In this soil is hit hard by sharp end chisel.
Dewatering: dewatering of dredge hole is done to reduce buyout force
on well thus promoting sinking.
Flushing with jet of water on the outside face of well reducing skin
friction
Tilt and shift:
 Tilt and shift are deviation of well from its proposed position and
orientation.
 Max. tilt allowed is 1/80
 Max. shift allowed is 150mm
Measures to avoid tilt and shift
 The outer surface of steining and curb should be kept as smooth
as possible.
 The radius of well curb should be kept more than the steining.
 The dredging should be done on all sides of well uniformly
Causes
 Eccentric dredging
 Can be caused due to boulder under one side

22. Method of checking tilt and shift
 Tilt and shift are calculated with the help of a level and total
station.
Method:
 Difference between height of points (1& 3)= R.L.(1)-R.L.(3)
 Tilt = [ R.L.(1)-R.L.(3)]/diameter Shift at bottom from top position
= tilt/ length
 Note : this process is repeated on sides (2 & 4) and in similar
manner tilt is obtained and then combined tilt and shift is
reported.
 Shift of well at top is measured by total station.
2
1 3
4

23. Correcting tilt and shift
 Regulation of Grabbing
 Eccentric Loading
 Strutting The well
 Water jetting or Digging Pit outside the higher side of well
 Pulling the well or caisson
 Excavation on the higher side outside the well
Problems:
Sand blowing- This problem occurs when well bottom rests on sandy
strata and dewatering is done below water table. In this sand from
ground gushes into the well and there is sudden sinking of well. This
sudden sinking is very dangerous and is very difficult to rectify.
Bridge scour -is the removal of sediment from bed such as sand and
rocks from around bridge, abutments or piers. Scour, caused by swiftly
moving water, can scoop out scour holes, compromising the integrity of
a structure.
Sand heaving-When a well passes through soft strata over a
considerable depth, the upward resistance acting on the outside
surface of the well is less than the weight of the well. In that situation
the well sinks down and quite often a heap is formed inside the dredge
hole.