Ce 6413 Suvey Practical Ii Lptc 0 0 4 2

3

PREPARED BY

C.LOGANATHAN, M.E.,

Assistant Professor

CE 6413 SUVEY PRACTICAL – II LPTC 0 0 4 2

ANNA UNIVERSITY SYLLABUS

OBJECTIVE

At the end of the course the students will posses knowledge about survey field techniques.

1.  Study of theodolite.

2.  Measurement of horizontal angles by reiteration, repetition and vertical

angles.

3.  Theodolite survey traverse.

4.  Height and distances – Triangulation – Single Plane Method.

5.  Tachometry – Tangential system – Stadia system – Subtense bar system.

6.  Setting out works – Foundation Marking – Simple curve right/ left handed –

Transition curve.

7.  Field observation for Calculation of azimuth.

8.  Field work using total Station

Total Hours: 60

GENERAL INSTRUCTIONS

1. All the students are instructed to wear protective uniform, shoes and cap before entering into the laboratory.
2. Before starting the exercise, students should have a clear idea about the principles of that exercise.
3. All the students are advised to come with completed record and corrected field book of previous experiments, defaulters will not be allowed to do their experiment.
4. Don’t operate any instrument without getting concerned staff member’s prior permission.
5. All the instruments are costly. Hence handle them carefully, to avoid fine for any breakage.
6. Utmost care must be taken to avert any possible injury while on laboratory work. Incase, anything occur immediately report to the staff members.
7. One student from each batch should put his/her signature during receiving the instrument in instrument issue register.
8. Don’t adjust the permanent adjustment screws of theodolite and levelling instrument to avoid the collection of fine amount equivalent to the servicing charge of the particular instrument.

CONTENTS

Ex.No.

/

Name of the Exercises

/

Page No

THEODOLITE SURVEYING

01  / Study of theodolite. / 06
02  / Determination of horizontal angles by reiteration method / 09
03  / Determination of horizontal angles by repetition method. / 12
04  / Determine the vertical angle to the given objects. / 14
05  / Closed traverse by method of included angles / 16

TRIANGULATION SURVEY

06  / Determine the horizontal angle measured from satellite station. / 19
TRIGONOMETRICAL LEVELLING
07  / Determine the elevation of the objects by Single Plane Method. / 24
08  / Determine the elevation of the objects by Double Plane Method. / 28
TACHEOMETRIC SURVEYING
09  / Determination of tachometric constant by stadia method. / 33
10  / Determination of gradient of a line by stadia method. / 35
11  / Determination of gradient of a line by Tangential Tacheometry. / 39
12  / Determination of Area by Tangential Tacheometry / 44
13  / Determination of gradient of the line joining staff station and the target by Subtense Bar method / 47
SETTING OUT WORKS
14  / Setting out of the foundation for a building. / 52
15  / Setting out simple circular curve by long chord method. / 55
16  / Setting out simple circular curve by Rankin’s method. / 60
17  / Setting out transition curve. / 63

ASTRONOMICAL SURVEY

18  / Azimuth by the Ex – Meridian Observation on the sun / 66

ELECTRONIC SURVEY

19  / Field work using Total Station / 69

Exercise No .1 Date:

STUDY OF THEODOLITE

DESCRIPTION:-

The theodolite is the precise instrument designed for the measurement of horizontal angle and

vertical angle and has a wide applicability in surveying such as laying of horizontal angle,

locating points on line, prolonging survey lines, establishing grades, determining difference in

elevation, setting out curves etc.

PARTS OF A TRANSIT THEODOLITE:-

The telescope can be revolved through a complete revolution about its horizontal axis in a vertical plane.

A. Levelling head:

1.  A Levelling head consists of two parallel triangular plates known as tribrach plates.

2.  The upper tribrach has three arms each carrying a Levelling screw.

3.  The main functions of the Levelling head is,

(a) To support the main part of the instruments.

(b) To attach the theodolite to the tripod.

(c) To provide a mean for leveling the theodolite.

B. Telescope:

1.  It is mounted on a spindle known as horizontal axis or trunnion axis

C. Vertical circle:

1.  It is a circular arc attached to the trunnion axis.

2.  By means of vertical clamp screw and tangent screw the telescope can be accurately set at any desired position in vertical plane.

3.  The graduation in each quadrant is numbered from 0° to 90° in opposite directions.

D. Index Frame:

1.  At the two extremities, two Vernier are fitted to read the vertical axis.

2.  When the telescope is moved in a vertical plane, the Vertical circle moves relative to the Vernier with the help of which reading can be taken.

3.  A long sensitive bubble tube is placed on the top of the index frame.

E. Standards (or) A – Frame:

1.  This stands upon the Vernier plate to support the horizontal axis.

F. Two Spindles:

1.  The two axes have a common axis, which forms the vertical axis of the instruments.

G. Lower plate:

1.  It carries a horizontal circle graduated from 0° to 360° in a clockwise direction as silvered, beveled edge.

2.  By means of clamp screw and tangent screw this can be fixed at any desired position.

H. Upper plate:

1.  It also carries clamp and tangent screw to accurately with the lower plate.

2.  On clamping the upper clamp and unclamped lower clamp, the instrument can rotates on its outer axis without any relative motion between the two plates.

3.  If the lower clamp is clamped and upper clamp unclamped, the upper plate and the instrument can rotate on the inner axis with a relative motion between the Vernier and the scale.

4.  For using any tangent screw, its corresponding clamp screw, its corresponding clamp screw must be tightened.

I. Level tubes:

1.  This upper plate carries two level tubes placed at right angles to each other in which one is kept parallel to the trunnion axis.

2.  Theses can be centered with the help of foot screws.

J. Plumb Bob:

1.  This is suspended from the hook fitted to the bottom of the inner axis to canter the instruments exactly over the station mark.

TEMPORARY ADJUSTMENTS:

A.  Setting over the station:

1.  Centre the instruments over the station marked by a plumb bob.

2.  Level approximately with the help of tripod leg.

B. Levelling Up:

1.  Do these using three-foot screws similar to that of Levelling instrument.

C. Elimination of Parallax:

1.  By focusing the eyepiece for distinct vision of the cross hairs.

2.  By focusing the objective to bring the image of the object in the plane of cross hairs.

IMPORTANT TERMS:-

1.  Vertical Axis:- The axis about which the theodolite may be rotated in a horizontal plane.

2.  Horizontal Axis:- The axis about which the telescope along with the vertical circle of a theodolite may be rotated in a vertical plane.

3.  Axis of telescope:- The axis about which the telescope may be rotated is called axis of telescope.

4.  Axis of the level tube:- The straight line that is tangential to longitudinal curve of the level at its centre is called axis of the level tube.

5.  Centering:- The process of setting up theodolite exactly over the groundwork station is called known as centering.

6.  Transiting:- The process of turning the telescope in vertical plane through 180° about its horizontal axis is called transiting.

7.  Swing:- A continuous motion of the telescope about the vertical axis in horizontal plane is called swing the swing may be either in face left or right.

8.  Face left observation:- The observation of angles when the vertical circle is on the left side of scope.

9.  Face right observation:- The observations of angles when the vertical circle is on the right of the telescope.

10.  Changing the face:- The operation of changing the face of telescope from right to left and vice-versa.

11.  set:- A set of horizontal observations of any angle consists of two horizontal measures one on the left face and other on the right face.

12.  Telescope normal:- A telescope is said to be normal when its vertical circles is to its left and bubble of the telescope is up.

13.  Telescope inverted:- A telescope is said to be inverted or reversed when its vertical circle is to its right and the bubble of the telescope is down.

Determination Of Horizontal Angle –Reiteration Method. / Face : Right Swing : left / Avg.
Included
Angle / “
’
o
Included
Angle / “
’
o
Mean / “
’
o
B / “
’
o
A / “
’
o
Face : Left Swing : Right / Included
Angle / “
’
o
Mean / “
’
o
B / “
’
o
A / “
’
o
Sight to / A / B / C / D / E / A
Inst.
At / O

Exercise No .2 Date:

DETERMINATION OF HORIZONTAL ANGLE (REITERATION METHOD)

Aim:-

To determine the included angle between the given objects (A, B, C and D) by reiteration method.

Instruments Required:-

Theodolite, Tripod, Ranging rods.

Procedure: -

1.  Set the instrument over “O” which should be at the center of the arrangement of the given objects.

2.  Do all the initial adjustments and keep the vertical circle to left.

3.  Set Vernier A to 0°0’0” , bisect the ground point “A” and turn the telescope to bisect object B by loosening the upper clamp screw and upper tangent screw.

4.  Read t\both Vernier. The mean of the Vernier readings will give the angle AOB

5.  In the same way bisect the other objects in clockwise direction and note down the readings.

6.  Since the graduated circle remains in a fixed position throughout the entire process, each included angle is obtained by taking the difference between two consecutive readings.

7.  On final sight to A the reading of the Vernier should be the same as the original settings. If not, note the reading and find the error due to slips ect., If the error is small, distribute it equally to all angles, if large, repeat the procedure and a fresh set of readings.

8.  Do the same procedure with the other face in anticlockwise direction.

A

B

E O

C

D

Results :-

The Horizontal Angle between the given points by

REITERATION method are ______

Determination Of Horizontal Angle –Repetition Method. / Face : Right Swing : left / Avg. Horizontal
Angle / “
’
o
Horizontal
Angle / “
’
o
No. of rep.
Mean / “
’
o
B / “
’
o
A / “
’
o
Face : Left swing : Right / Horizontal
Angle / “
’
o
No. of rep.
Mean / “
’
o
B / “
’
o
A / “
’
o
Sight to
Inst.At / O

Exercise No .3 Date:

DETERMINATION OF HORIZONTAL ANGLE (REPETITION METHOD)

Aim :-

To determine the included angle between two object stations P and Q by using repetition method.

Instruments Required:-

Theodolite, Tripod.

Procedure :-

1.  Set the instrument at “O” approximately at the middle of the given objects to avoid too obtuse and too acute angles.

2.  Do all initial adjustments and keep the vertical circle at left hand side.

3.  Set 0° at Vernier A with the help of upper clamp and tangent screws.

4.  Loosen the lower clamp screw and direct the telescope towards the objects P.

5.  Tighten the lower clamp and bisect point P accurately by lower tangent screw.

6.  Unclamp the upper clamp screw and turn the telescope clockwise towards “Q”

7.  Clamp the upper screw and bisect “S” accurately by upper tangent screw.

8.  Note the reading of verniers A and B to get the angle of POQ.

9.  Loosen the lower clamp screw. Turn the telescope to sight “P” again and bisect accurately by lower tangent screw.

10.  Repeat steps 5 to 9 until the angle is repeated to the required number of repetitions.(usually 3)

11.  Change the face to right, and set the Vernier A to 180° to eliminate graduation error in horizontal circle and note the readings similarity as above.

Calculation:-

To find the horizontal included angle divide the total angle by the number of repatriations.

Result: -

Average Horizontal angles of POQ, QOR, ROS, SOP

S P

O

Q

R

Determination of vertical angle :- / Face: Right / Avg. Vertical
Angle of Faces / “
’
o
Vertical
Angle / “
’
o
Mean / “
’
o
D / “
’
o
C / “
’
o
Face: Left / Vertical
Angle / “
’
o
Mean / “
’
o
D / “
’
o
C / “
’
o
Sight to
Instrument at

Exercise No .4

DETERMINATION OF VERTICAL ANGLE

Aim :-

To determine the vertical angle to the given objects.

Instruments Required: -

Theodolite, Tripod.

Procedure: -

1.  Set up the instrument at any convenient place to cover all the given points.

2.  Level the instrument with reference to the altitude bubble by using foot screws as in the case of horizontal bubble Levelling.

3.  Set the zero of the vertical Vernier exactly in coincidence with the zero of the vertical scale.

4.  Loosen the vertical plane until the focused object is bisected use tangent screw for accurate bisection.

5.  Read both the verniers C and D of vertical circle.

6.  Denote the depression angle with negative sign.

7.  Similarly bisect all other objects and find out the readings accurately.

8.  Change the face and follow the steps 4 to 6 above.

Results :-

The Vertical angle is = …………….

C

a

b

A B

Closed traverse: / Face : Right Swing : left / Avg.
Included
Angle / “
’
o
Included
Angle / “
’
o
Mean / “
’
o
B / “
’
o
A / “
’
o
Face : Left swing : Right / Included
Angle / “
’
o
Mean / “
’
o
B / “
’
o
A / “
’
o
Sight to / A / B / C / D / E / A
Inst.
At / P

Exercise No .5 Date:

CLOSED TRAVERSE BY INCLUDED ANGLE METHOD