levelling

STUDENTS NAME ID.NO. ENROLLMENT NO.KAKADIYA KRUSHAL 13PES-35 130080125006DHRUVIT KARDANI 13PES-03 130080125007SHYAM GOVANI 13PES-09 130080125005UTKARSH DUBEY 13PES-34 130080125033VISHAL LAPSIWALA 13PES-22 130080125010SMIT PATEL 13PES-07 130080125030

BIRLA VISHVAKARMA MAHAVIDYALAYA (ENGINEERING COLLEGE) VALLABH VIDYANAGAR

SUBJECT: ELEMENTS OF CIVIL ENGINEERING (CODE-2110004) BE First Level First Semester (Self Finance)TOPIC: LEVELLING PREPARED BY:

LEVELLING

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A surveying method that yields elevations at definite points along a reference line.

Profile leveling establishes a side view or cross sectional view of the earth’s surface

Primary use is for utilities:A. HighwaysB. CanalsC. SewersD. Water mainsE. SidewalksF. Retaining wallsG. Fences

All of these need accurate information about the topography along the route.

Definition:

Characteristics

May be a single segment.

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May be straight segments connected with curves.

May be multiple segments which change directions with angle points.

Procedure

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It is a common practice to use a procedure called stationing.

1. Stations are established at uniform distances along the route.

2. Standard station distance is 100 feet.

3. Half or quarter stations are used when the topography is very variable.

4. The distance from the starting point to the station is used as the station identification.

Procedure-cont.

Intermediate foresights: foresights taken at stations that are not used as benchmarks or turning points.

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Intermediate foresights are recorded at each standard

station and at additional stations as needed to define the

topography of the route.

Purpose is to define the topography along the

route.High points

Low points

Changes in slope

Critical points

Roads

Highway

Gutters

Sidewalks

Defining an Object Because profile leveling is used to measure the

cross section of and the location of objects along a route, one important issue is determining how many stations are required to define the object.

The answer is, it depends on the object and the use of the data.

For example: how many stations would be required to define the cross section of a standard trapezoidal ditch?

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An Object-Ditch --contA ditch may have been a trapezoid

when constructed, but over time it will change its shape.

What is the effect on the number of stations if a channel has developed in the bottom of the ditch?

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An Object-Street

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Another common object is a street.The number of stations required to define

the cross section of a street depends on the required information.◦Do you need to know the height of the curb?

Turning Points-cont.

When distances to foresights become too long or when the terrain obstructs the view of the instrument, turning points are established.

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Foresights on turning points and benchmarks are true foresights.

Profile leveling is differential leveling with the addition of intermediate foresights.

Profile Data Table:

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STA BS HI FS IFS ELEV

ExampleIn the first example the existing sidewalks

were used as benchmarks because they were part of the finished design.

When there are no existing structures that can be used for a benchmark, or when all of the existing structures will be removed during construction, a benchmark must be established out side of the construction zone.

In this situation, the notes are started different.

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Profile with side bench mark

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Step 1 The principles are the same. The difference is that in this case the BS is taken on the

benchmark not the first station.

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The notes use the same column--they just start with the BM instead of 0.0.

STA BS HI FS IFS ELEVBM1 8.2 108.2 100.0

Step 2 Record the first foresight. In this example the first foresight (0+00) is an intermediate foresight.

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STA BS HI FS IFS ELEV

BM1 8.2 108.2 100.0

0.0 9.2 99.0

Step 3 Add additional intermediate foresights as needed until the first

turning point is reached.

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STA BS HI FS IFS ELEV

BM1 8.2 108.2 100.0

0.0 9.2 99.0

156.5 6.5 101.7

358.6 1.3 106.9

Step 4 Move the instrument and continue recording foresights.

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STA BS HI FS IFS ELEVBM1 8.2 108.2 100.0

0.0 9.2 99.0

156.5 6.5 101.7

358.6 2.1 109.0 1.3 106.9

458.6 5.2 103.8

522.6 7.7 101.3

598.2 5.4 103.6

Step 5Close the loop:

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STA BS HI FS IFS ELEV

BM1 8.2 108.2 100.0

0.0 9.2 99.0

156.5 6.5 101.7

358.6 2.1 109.0 1.3 106.9

458.6 5.2 103.8

522.6 7.7 101.3

598.2 10.4 114.0 5.4 103.6

BM1 14.0 100.0

Sum 20.7 20.7

0 = 100.0-100.0 0

AE =K M =0.1 x 598.2 x 2

5280=0.047