Tuesday, March 4, 2014

Survey Method 03-Leveling

Leveling is a branch of surveying. The object of which:
I. To find the elevations of give points with respect to a given or assumed datum
II. To establish to point at a given elevations or at difference elevations  with respect to a given or assume datum

The first operation is required to enable the works to be destined wild the second operation is required in the setting out of all kinds of engineering works. Leveling deals with measurement in vertical plumes.

Level surface

A leveling surface is define as a curved surface which at each point is perpendicular to a directions of gravity at the point the surface of a steel water is a truly level surface. any surface pararal to the mean spheroidal of the earth is there for a level surface.

Level line

A level line is a line laying in a leveling surface. it is there for normal to the plumb line at all points.
Horizontal plane - Horizontal plane true a point is a plane tangential to the level surface at that point. It is there for perpendicular to the plumb line through the point.
Horizontal line
It is strength line tangential to the level line at a point. It is also perpendicular to the plumb line through the point

Vertical line

It is a line normal to the level line at the point it is commonly considered to be the line deference by plumb line.

Datum

Datum is any surface to witch elevations are reflect the mean sea level affords a convention datum world over, and elevations are commonly given as so much oblive or billow sea level. It is often more convenient, however to assume some other datum specially if only the relative elevations of points are required.

Elevations

The elevations of a point on or near the surface on a earth is it’s vertical distance above or below and arbitrarily assume level surface or datum. The deference in elevations between 2 points is a vertical distance between the 2 level surface in which the 2 points lie.

Vertical angle

Is an angle between to intersection lines in a vertical plane. Generally on of this line is horizontal. Mean sea level M.S.L.  is a coverage height of the sea for all stagers on the tides. At any perpendicular place it is derived by averaging the hourly time height over a long period of 19 years

Bench mark

Bench mark is a relative permanent point of reference hours elevations with respect to some assume datum is known. It is used ether as a starting points for leveling for as a point upon which to close as check.