Introduction of Surveying & Levelling:
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Surveying & Levelling is an essential part of Architecture as well as in the construction process. They deal with determining the relative positions of various points as well as elevation levels on the surface of the earth. Both Surveying and Levelling has its types, classifications, methods and instruments for determining the positions.
So, in this post, we are discussing the Introduction of Surveying and Leveling. Also, its classifications and instruments used in Surveying and Levelling.
Surveying is the phenomenon, which deals with determining the relative positions of various points on or below the earth surfaces. The relative positions are also determining by measuring the vertical & horizontal distances and angles accurately by using various Surveying Instruments.
Surveying can also be understand by the various followings:
- To determine the relative positions of the existing features on or above the ground.
- To determine various quantities related to construction i.e. Volumes, Areas, etc.
- To mark the position of the proposed structure on the ground surface.
The method of Surveying is classified into two different types:
Plane Survey is for measuring small areas (less than 2500 sq. km). In this survey, we assumed that the curvature of the earth is to be flat. The spherical angles are assuming as plane angles. Plane Survey is less accurate than any other Survey.
Geodetic Survey is for measuring large areas (more than 2500 sq. km). In this survey, the curvature of the earth is taken into consideration. Also, it provides a high standard of accuracy. Also, it is more accurate than the Plane Survey. It is generally used for establishing reference points or control points.
Levelling is a method of surveying used for determining the difference of levels or the elevations levels of various points on the surface of the earth. It is also essential for determining the undulations of the earth surface for topographic mapping. Levelling plays an important role in the construction process for the layout markings, excavation levels, etc. Also, it is very useful for the designing of bridges, dams, railway canals, sewers, etc.
READ: CLIMATIC ZONES OF INDIA
Functional Classification of Surveying & Levelling:
1. Control Surveying-
It works on the principles of Geodetic Survey. The Survey of India is work on Conduct Survey.
2. Land Surveying-
Land Survey is also known as the Property Survey, Boundary Survey or Cadastral Survey. It is used for determining the boundaries and areas of lands.
3. City Survey-
City Survey is conducted in the limits of the city, for city or urban planning. It is useful for the marking or layout of streets, buildings, sewer lines, etc.
4. Topographical Survey-
Topographical Survey is defined by the shape or configuration of the earth surface. They are, for establishing the horizontal as well as vertical points on the earth surface.
5. Route Survey-
Route Survey is a type of Topographical Survey. These surveys are, for roads or the proposed routes for highways, railways, etc.
6. Mine Survey-
Mine Survey is used for underground works. For determining the relative position and levels of shafts, mines, boreholes, etc.
7. Hydro-graphic Survey-
Hydro-graphic Survey is conducted on or near the water body such as lakes, rivers, harbours, etc. Marine Survey is a special type of Hydro-graphic Survey.
8. Engineering Survey-
Engineering Surveys are conducted for collecting data regarding the designing and the planning. These surveys collect information regarding various construction works such as buildings, roads, bridges, dams, reservoir’s, sewers, etc.
9. Astronomic Survey-
Astronomic Surveys are conducted for the determination of latitudes, longitudes, azimuth’s angles, local time, etc. for various places on the earth surface. These surveys are, by observing heavenly bodies i.e. the Sun and the Moon.
10. Satellite Survey-
Satellite Surveys are conducted by artificial earth satellites. For determining the inter-continental, inter-dam and inter-island geodetic ties all over the world.
11. Construction Survey-
Construction Survey is also known as the Location Survey. These surveys are conducted for determining the information requires for the preparation of plans, sections, elevations, etc.
12. Geological Survey-
Geological Surveys are conducted for collecting data from different strata or surface of the earth for geological studies.
Instruments Used for Different Measurements:
1. Horizontal Distance-
Chains, Tapes, Tachometer, EDM (Electronic Distance Measurement), etc.
2. Vertical Distance-
Levelling Instruments, Tachometer, etc.
3. Horizontal Angles-
Magnetic Compass, Theodolites, (Wikipedia) Sextants, etc.
4. Vertical Angles-
Theodolites, Clino-meters, Sextants, etc.
Types of Measuring Scales:
1. Plain Scale-
A plain scale measures units and sub-multiples. Examples: Meters and Centimetres
2. Diagonal Scale-
A diagonal scale measures units, sub-multiples and its further sub-multiples. Examples: Meters, Centimetres and Decimetres.
3. Chord Scale-
The chord scale is for measuring angles, without using a protector or any other device. It is rectangular in shape.
SURVEYING & LEVELLING PDF
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