THEODOLITE SURVEY - Civil Engineering short notes

THEODOLITE SURVEY


THEODOLITE SURVEY 

• Universal instrument 
• Accurately measure horizontal and vertical angle with accuracy pf 20 sec 
• The diameter of the graduated circle on the lower plate determines the size of theodolite 
• Size of theodolite varies from 8cm to 25cm 
• 8 cm to 12cm instruments are used for general survey and engineering work 
• 14cm to 25cm instruments arc used for triangulation work. 

CLASSIFICATION OF THEODOLITE 


1. Transit Theodolite: If the telescope of a theodolite can be revolved through a complete revolution about its horizontal axis in the vertical plane, it is called a transit theodolite . 

2. Non transit theodolite : If the telescope of a theodolite cannot be revolved through a complete revolution about its horizontal axis in the vertical plane, it is called a non-transit theodolite. eg: Plane or Y, and fa-crest theodolite. 

3. Vernier and manometer theodolite : According to verniers or micrometers fitted to read the graduated circles, theodolites are also classified as Vernier theodolites, and micrometer thodolites 

PARTS OF A THEODOLITE 


1. TELESCOPE 


2. LEVELLING HEAD 
• Consist of an upper tribrach and a lower tribrach ( trivet ) 
• Had 3 foot screws in between 

3. THE TWO SPINDLES 
• There are two spindles one inside the other. 
• The outer spindle is hollow 
• Inner spindle is solid 
• Axis of both spindle should coincide 

4. THE LOWER CIRCULAR PLATE / SCALE PLATE 
• The lower plate is attached with the outer spindle. 
• Its beveled edge is graduated from 0 to 360 in a clockwise direction. 
• The lower plate is attached to the upper tribrach with lower clamping screw and tangent 

5. THE UPPER PLATE / VERNIER PLATE :- 
• The upper plate, is attached to the inner spindle. 
• Vernier plate and scale plate are fixed using upper clamping screw. 
• The upper plate carries two Vernier with magnifiers placed 180apart. . 

6. STANDARDS / A FRAME 
• 2 standards stand up on the upper plate to support trunnion axis 
• The Vernier plate complete with the standards and telescope is called the alidade of the theodolite 

7. VERTICAL CIRCLE 
• Mounted on the trunnion axis 
• Graduations are in clockwise and anticlockwise direction from 0 - 90 in all 4 quadrants 
• Line joining 0 s will be parallel to the line of collimation 
• Line of collimation is horizontal if Vernier reads 0 

8. INDEX FRAME / T FRAME 
• T shaped frame mounted on trunnion axis in front of the vertical circle 
• Horizontal arm is called index arm 
• Vertical arm is called clipping arm 

9. PLATE LEVEL 
• 2 spirit level at right angle to each other on upper plate 

10. ALIDADE LEVEL 
• A long sensitive bubble tube attached to the top of index frame 

11. STRIDING LEVEL 
• Used to check the horizontality of the trunnion axis 

12. PLUM BOB 
• Suspended from the lower end of the trivet 


TERMS 

1. TRANSITING/ PLUNGING / REVERSING : process of turning the telescope about its horizontal axis through 180* in vertical plane. 

2. SWINGING THE TELESCOPE : turning the telescope about vertical axis in the horizontal plane, CW right , ACW left swing 

3. CENTERING : it means setting the theodolite exactly over a station mark. it is done by means of a plumb bob 

4. FACE LEFT:- If the vertical circle of the instrument is on the left of the observer, the position is called face left /// 

5. TELESCOPE NORMAL / DIRECT : It means "bubble up" and the "face" of the vertical circle left. 

6. TELESCOPE INVERTED / REVERSED : It means "bubble down" and the "face" of the vertical circle right. 

7. CHANGE FACE : shifting from left face to right face, includes transiting and swinging 

8. VERTICAL AXIS : The vertical axis is the axis about which the telescope can be rotated in the horizontal plane. 

9. HORIZONTAL /TRUNNION /TRANSVERSE AXIS : Axis about which the telescope can be rotated in a vertical plane 


ADJUSTMENTS 

1. PERMANENT ADJUSTMENTS 

i. Vertical axis perp. To trunnion axis 
ii. Axis of plate level perp. Vertical axis 
iii. Axis of altitude level // to line of collimation 
iv. Line of collimation coincide with axis of telescope 
v. Vertical must read 0 when line of collimation is horizontal 

2. TEMPORARY ADJUSTMENTS 
i. Centering 
ii. Levelling 
iii. Elimination of parallax 

MEASUREMENT OF HORIZONTAL AXIS 

1. REPETITION 
• Used when finer degree of accuracy is required than the least count 

2. DIRECTION / REITERATION / METHOD OF SERIES 
• Suitable for measurements of angles having common vertex point 

ERRORS ELIMINATED IN REPETITION METHOD 
• Error due to eccentricity is eliminated by taking both Vernier reading 
• Error due to inadjustment of line of collimation and trunnion axis is eliminated by taking both fac ereading 
• Error due to inaccurate graduations are reduced by talking reading from different part of graduated circle 
• Error due to inaccurate bisection is eliminated by taking average of multiple observations



video below has  the previous year questions asked for kerala psc civil engineering technical exams



Comments

Post a Comment

Popular posts from this blog

UNITS OF MEASUREMENTS, PAINTING COEFFICIENT, OUT TURN, QUANTITY CALCULATION

Image
  DEDUCTION  • MASONRY : < 0.1 m2 - no deduction  • PLASTERING :  < 0.5 m2 - no deduction  0.5 - 3 m2 - one side deduction  > 3 - both side deduction  • End of beams, rafters, purlins < 0.05 m2 - no deduction  • Bearing of floors, roof slabs etc. - no deduction DIGREE OF ACCURACY  • Volume - 0.01 m3  • Area - 0.01 m2  • Dimension - 0.01 m  • Weight - 1kg  QUANTITY CALCULATION  PCC  • Maximum size of aggregate 40 mm  • For 1 m3 PCC - 0.95 m3 coarse aggregate is required  RCC  • Maximum size of aggregate 20 mm  • For 1m3 RCC - 0.90 m3 coarse aggregate is require  RCC For 1:1.5:3  Wt of cement = (1/3) x 0.90 x 1440 = 432 kg  Wt of sand = (1.5/3) x 0.90 x 1600 = 747 kg  PCC For 1:4:8  Wt of cement = (1/8) x 0.95 x 1440 = 171 kg  Wt of sand = (4/8) x 0.95 x 1660 = 760 kg PLASTERING  1:3 - 0.14 m3 / 10 m2 (sand) cement = (1/3) x 0.14 x 1440 = 67 kg  1:4 - 0.15 m3 / 10 m2 (sand) cement = (1/4) x 0.15 x 1440 = 54 kg  1:5 - 0.15 m3 / 10 m2 (sand) cement = (1/5) x 0.15 x 1440 = 43 kg
Read more

MACHINE TOOLS - SHAPER MACHINE

Image
The shaper is a machine tool used primarily for:  1. Producing a flat or plane surface which may be in a horizontal, a vertical or an angular plane.  2. Making slots, grooves and keyways  3. Producing contour of concave/convex or a combination of these Working Principle: The job is rigidly fixed on the machine table. The single point cutting tool held properly in the tool post is mounted on a reciprocating ram. The reciprocating motion of the ram is obtained by a quick return motion mechanism. As the ram reciprocates, the tool cuts the material during its forward stroke. During return, there is no cutting action and this stroke is called the idle stroke. The forward and return strokes constitute one operating cycle of the shaper.  Construction: The main parts of the Shaper machine is Base, Body (Pillar, Frame, Column), Cross rail, Ram and tool head (Tool Post, Tool Slide, Clamper Box Block). Base:  - The base is a heavy cast iron casting which is fixed to the shop floor.  - It supports
Read more

OPEN QUIZ RANKLIST 3

 1 56 / 63 HaRitHa 2 54 / 63 Sebin 3 53 / 63 Anuja sundareshan 4 53 / 63 Arun aravind 5 52 / 63 Faiz 6 51 / 63 aparna B 7 51 / 63 Veni 8 51 / 63 Anaswarakp 9 51 / 63 Akshay k 10 51 / 63 Minnu 11 50 / 63 Zehmat 12 50 / 63 Hima 13 49 / 63 Sreejith tk 14 48 / 63 AISHU 15 47 / 63 Prasee 16 47 / 63 Aswaniraj 17 46 / 63 Mumtaz 18 46 / 63 Ganga 19 45 / 63 Hannath N M 20 45 / 63 Arya... 21 44 / 63 Greesh 22 44 / 63 ANU M 23 43 / 63 Archana 24 43 / 63 Nirosha 25 43 / 63 CG 26 43 / 63 Nisham 27 43 / 63 Nikhil Murali 28 43 / 63 Suneesh 29 43 / 63 Aswathy 30 43 / 63 remya basanth 31 42 / 63 Haritha 32 41 / 63 Mohamed Hafeez 33 41 / 63 Aswati 34 41 / 63 salma  35 41 / 63 Akhila Ag 36 40 / 63 Gp 37 40 / 63 Aleena 38 40 / 63 Aami 39 40 / 63 Vrindha  40 39 / 63 Aiswaryasajeevan  41 38 / 63 Spread a smile 42 38 / 63 ashlin stanly 43 38
Read more