Extensive Survey Camp PDF
Extensive Survey Camp PDF
Extensive Survey Camp PDF
1. INTRODUCTION
The second stage work of investigation includes the survey work at the
site in order to collect the data necessary for the design of project elements,
preparation of drawings, estimates etc. the office work is confined to the
designs, drawings and estimates of the project.
The catchment area of proposed New Tank determined from the toposheet is
14 Km2.
The rainfall of a bad year is always taken as 2/3 of mean amount of rainfall.
Assuming as 20%
100
Yield from catchment (14X106) x 10.6 cum/year
100
= 1.48 X 106 cum/year.
The need for irrigation can be summarized in the following four points:
Less rainfall:
When the total rainfall is less than that needed for the crop, artificial
supply of water is necessary. In such a case, irrigation system should be
developed at the place where more water is available and then, the means to
convey water to the area where there is deficiency.
Non-uniform rainfall:
It adds water to the soil to supply moisture essential for the plant
growth.
It washes out all diluted salts in the soil.
It reduces the hazard of soil piping.
Duty:
Delta:
Delta is the total depth of water required by a crop during the entire
period from the day of sowing to harvesting.
Crop period:
Crop period is the time, in days, that a crop takes from the instant of
its sowing to its harvesting.
Base period:
Base period for a crop refers to the whole period of cultivation from
the time of first watering for sowing the crop, to the last watering before
harvesting.
Relation between duty (D), delta (D) and base period (B) in metric
system
Let there be a crop of base period b days. Let one cumec of water be
applied to this crop on the field for B days.
Now, the volume of water applied to this crop during B days (V)
V = (1x60x60x24)m3
By definition of duty (D), one cubic meter supplied for B days matures D
hectares of land.
= Volume/Area
Therefore
Or
Consumptive use:
2. A study of the rocky out crop and a few boring is done to note the nature
of the foundation.
4. Nature and extent of land, roads, bridges, etc. that would be submerged by
the construction of the dam.
Keeping the above points in view, a thorough study was done were the final
choice of the site was made.
The following topography and geological features affects the selection of site
for earthen dam.
1. The water storage should be largest for the minimum possible height and
length. The site should be located in a narrow valley.
6. Value of the property and land likely to be submerged by the proposed dam
should be sufficiently low in comparison with the benefit expected from the
project.
After selection the site, final and precise investigation was carried out. In the
present survey work it was assumed that a choice of site was made and the
type of dam to be constructed is of earthen dam, with this assumption the
detailed survey were carried out which includes.
A. Longitudinal and cross section along the centre line of the bund.
1. Set the levels near the P.B.M and carry out temporary adjustment.
2. Keep staff on permanent B.M and take readings and enter it as back sight
in the field book.
4. If the staff is invisible shift the level and note down the last reading as fore
sight, after shifting the level and temporary adjustment take readings of that
point and note down it as back sight.
Object: -
To obtain the Profile of the valley along the assumed center line of the
dam.
To estimate the quantity of earthwork for the proposed construction of
the bund the following points should be considered:-
TOP WIDTH
Top width of earth dam should be sufficient to keep the seepage line
well within the body of dam. It should withstand earthquake and wave
action. For small dams, top width is generally governed by minimum road
way requirements.
FREE BOARD:-
The Minimum height of free board for wave action is 1.5hw where hw =
max.ht. of wave.
Fetch is defined as the longest unobstructed distance for wind to blow from
one edge of reservoir up to the dam on u/s side of the dam. (Fetch can be
measured from capacity contour sheet) V is wind velocity in kms/hr.
1. Molitor’s formula
hw = 0.032 x sqrt (v x F)+0.763-0.271 x sqrt (sqrt(F))
F = 0.32km
v = 40kmph
hw = 0.673m
h/3
2. Zoned embankment type earth dam: It is the one in which the dam is
made up of more than one material. The most common type of a rolled
earth dam section is that in which a central impervious core is flanked by
zones of material considerably more pervious. Shown below is a typical
cross-section of a Zoned Embankment type earth dam.
TRANSITION
FILTER
RIP RAP
ROCK TOE
CORE
(IMPERVIOUS)
DIAPHRAGM
PERVIOUS FOUNDATION
IMPERVIOUS
CH MH
SM 4:1 2.5:1
CL ML
CH MH
Though any one of the tables can be used for preliminary selection of
the bund section the current practice has been in favour of Strange’s table.
1. Dumped
2. Placed (also called “Pitching”)
The minimum weight of each rock for rip rap is calculated by using
Iribarren – Hudson formula.
K 'S 3h3
W
(Cos Sin )3 (S 1)3
W= Minimum weight of Rock to be placed on rip rap in kN.
Fine Thickness
1) If the bottom of the cut off wall permeates into the impermeable layer
then cut off is called positive cut off wall. This type has the advantage of
reducing seepage loss, but the disadvantage of increasing neutral stress
due to water thus decreasing the factor of safety of slope – stability on u/s
side.
2) If the bottom of cut off wall does not permeate into loose stratum
completely, cut off is called “ Partial cut off wall”
The Minimum bottom width of cut off wall is 4m, side of at least 1:1 or
flatter slope may be provided in case of overburden. ½:1 or ¼:1 may be
provided in soft rock and hard rock respectively. It also prevents seepage,
erosion, and mass, instability, boiling and piping.
The toe drain is placed at D/s side toe of each dam. In small dams
only drains are provided. In large dams embankment will be saturated
below the phreatic line. And tow drain acts as a disposal zone of the
drainage water. Its height varies from 5% of dam height (above tail water
level), with external drainage system, to as much on 20% in small dams
with no internal drains. The Rock toe designed like protective filter except
for the gravel zone. The top width of rock toe will have the dimension same
as of berm.
If A1, A2, A3 … An, are the areas of successive contours, H being the
contour interval, then by Prismoidal rule. The storage capacity can be
calculated.
Using Prismoidal rule
V=
H
( A1 An ) 4( A2 A4 A6 ......) 2( A3 A5 A7 .......) cubic meter.
3
A = in sqm.
V=H/3((A1+An)+4(A2+A4+A6+...)+2(A3+A5+A7+...))
H/3 0.333333333
(A1+An) 17.02498046
4(A2+A4+A6+...) 173.222217
2(A3+A5+A7+...) 67.210416
858192.04 cum
85.82 ha-m
A detailed survey at the waste weir site is necessary to design the body wall of
waste weir, the approach and draft channel and other protective works and to
arrive at the cost of their work. In choosing the site for waste weir the
following points must be borne in mind:-
1. A saddle disconnected from the tank bund is the best site for a surplus
work.
3. The height of body wall must be minimum possible and should be located
as far as possible in cutting.
4. The soil should be hard both at the weir site and along the draft channel.
5. There should be natural diversion to lead the water safely from the bund.
A contour canal has been provided for the proposed bund. Its alignment is
similar to the figure shown below.
Channel alignment is meant to estimate the cost of the channel and cross
drainage works, and also to determine the gross command area.
The following points were kept in view while aligning the channel.
The area enclosed between center line of bund, the mother valley and the
final alignment is defined as gross command area. This area can be
calculated by using Planimeter or by constructing squares.
f 5/3
1 / 2392
Longitudinal slope of channel S= 3340Q1 / 6
Doddaballpur Taluk,
Bangalore district.
5. Bund
812.00 m.
T.B.L.
811.00 m.
M.W.L.
810.000 m.
F.T.L.
4. 19.20 m.
Max height of Bund
8. Canal
HIGHWAY PROJECT
The positioning or the laying out of the center line of the highway on
the ground is called the alignment. The horizontal alignment includes the
straight path, the horizontal deviations and curves. Changes in gradient
and vertical curves are covered under vertical alignment of roads.
Requirements:
Short
Easy
Safe
Economical
To plan a road network for efficient and safe traffic operation, but at a
minimum cost.
The cost of the construction, maintenance and renewal of pavement
layers and the vehicle operation costs must be given due considerations.
To arrive at a road system and lengths of different categories of roads,
which could provide maximum utility and can be constructed within the
available resources during the plan period under consideration.
To fix up date wise priorities for development of each road link based on
utility as the main criterion for phasing the road development program.
To plan future requirements and improvements of road in view of
anticipated developments.
To work out financing system.
A shortest route may have very steep gradients and hence not easy for
vehicle operation. Similarly, there may be construction and maintenance
problems along a route, which may otherwise be short and easy. Roads are
often deviated from the shortest route in order to cater for intermediate
places of importance of obligatory points.
Obligatory points
Traffic
Geometric design
Economics
Other constructions
In hilly areas, additional care has to be given for setting up the
alignment and the factors governing are as follows:
Stability
Drainage
Geometric standards of hill roads
Resisting length
Map Study
Reconnaissance Survey
Preliminary Survey
Location of Final Alignment
Detailed Survey
Materials Survey
Design
Earth Work
Pavement Construction
The following points may be kept in mind while aligning any type of
road:
DESIGN SPEEDS
Minimu
Minimu
Minimu
Minimu
Ruling
Ruling
Ruling
Ruling
Road
ion
m
NH&SH 100 80 80 65 50 40 40 30
MDR 80 65 65 50 40 30 30 20
ODR 65 50 50 40 30 25 25 20
VR 50 40 40 35 25 20 25 20
Mountain Steep
Classification of
Absolut
Absolut
Absolut
Absolut
Absolut
Ruling
Ruling
Ruling
Ruling
Ruling
Ruling
e
NH&SH 36 23 23 15 80 50 90 60 50 30 60 33
0 0 0 5
MDR 23 15 15 90 50 30 60 33 30 14 33 15
0 5 5
ODR 15 90 90 60 30 20 33 23 20 14 23 15
5
VR 90 60 60 45 20 14 23 15 20 14 23 15
While undertaking the initial alignment of the new highway project , it was
required that in the final alignment , we provide a smooth curve between 150
m chainage and 210 m chainage and another curve between 480m chainage
and 540m chainage. we have designed the curve as follows.
e+f= v^2/127 R;
where
0.22= 40*40/(127*R)
R req= 57.27 m
R Provided = 200m.
L= 104.55 m
HIGHWAY PROJECT
0 0.180 0.00 A1
60 0.00 7.87 A2
H/3 20
(A1+An) 0.00
4(A2+A4+A6+...) 36.04
2(A3+A5+A7+...) 3.28
872cum
H/3 20
(A1+An) 0.000
4(A2+A4+A6+...) 59.88
2(A3+A5+A7+...) 25.76
1718.2 cum
d) Pumping system
e) Distribution system.
2. Sewerage project:
a) Sewerage system
DATA:
a) Geological
b) Hydrological
c) Sanitary conditions
FACTORS:
Proposing slow sand filter & chlorination for the treatment of water.
Q max
Water surface area of filter =
Filtration rate
3153 .6
= 876 m2
150
L x B = 219
2B x B = 219
B = 10.46 m, say
B = 11.0 m, L = 22 m
Providing filter sand depth of 1 m, gravel depth varying from 30-75 cm say
50 cm, 50 cm free board and water depth of 1 m.
WQH
BHP where W= 1000 kg/m3(unit weight of water)
75 c
m x p = 80%
2gd
= flQ2
12.1 d5
(12.1 x .2255)
hf = 15.19 m
Providing a pipe of 22.5 cm & adding 10% minor loss due to valves.
‘H’ = Suction head (3m) + Delivery head (13.12 m) + Friction loss (hf) = 4.316
m + 3.0 m
= 23.436 m
(75 x .8)
BHP = 7.6 KW
6.0 ABBREVIATIONS: