Fundamentals of surveying

Fundamental of surveying

Surveying:It is an art of determining relative position of point with respect to a reference surface Above or blow that surface and presented either graphically or numerically.

Types of surveying

1. Plane surveying: In this, the earth surface is to be considered as a plane, Spherical shape is to be neglected.

Remember: Plane survey is used for small area.

2. Geodetic survey: In this, actual shape of earth is to be considered and the earth curvature should be taken into account.

Remember: 

1. Geodetic survey is used for large area.

2. Area greater than 195.5 kilometre square.But before It was 260km square.

3.Geodetic survey is done by Survey of India

4. Mumbai sea port is taken as mean sea level in India.

Classification of surveying

1. According to surface nature or purpose.

A. Topographical survey: 

This Survey is used to obtain details of natural or artificial features on the earth.

B. Hydrographic survey: 

This Survey is to be done on or near water surface.

C. Cadastral survey: 

This survey is used for property boundaries for legal purpose.

D. Astronomical survey:

This survey is used to locate an exact location of point on the earth. This is also used to find out latitude, longitude . local time etc.

2 . According to instrument

a. Chain survey: Only linear measurement

b. Compass survey: Horizontal angle

c. Theodolite survey: Horizontal and vertical angle

d. Levelling: Vertical distance

e. plane table survey: For maping.

3. According to organisation

a. military survey.

b. Mine survey.

c. Geological survey.

d. Marine survey.

e. Archlogical survey.

Principles of surveying

1. Control network:

In this principle a point can be located with the help of two known point.

      or

A measurement can be done from at least two point.

2. Whole to part: According To this  major pont should be located first and after it Miner control point.

Remember: 

~Whole to part is to be more  preferred because  in this error decreases and does not effect whole structure.

~ Part-to-whole may also be possible but we do not prefer it. Because the error may be accumulated and may be expanded to a greater extent.

Scales

Scale:

It is  the ratio of map length to the ground length.

Representative fraction:

When a scale  is represented in its fraction form and the term is  known as a representative fraction.

 Scale = map length / ground length 

scale = 1cm/ 1m

R.f=1cm/100cm

Types of scale

1. Plane scale: This scale used two units of linear dimension and for 2D mapping.

2. Diagonal scale: This scale uses three unit of

 dimension and preferred four 3D mapping. Diagonal scale works on principle of similar Triangle.

 

3. Shrunk scale:

Shrunk scale= original scale x shrinkage factor.

Shrinkage factor= shrunk scale/ original scale.

   

By team an_engineer_bro