Geomatic Levelling Report

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FACULTY : ENGINEERING

TECHNOLOGY EDITION:

DEPAERTMENT OF CIVIL

ENGINEERING TECHNOLOGY REVISION NO: EXPERIMENT: LEVELLING

(ESTABLISH TBM) EFFECTIVE DATE: AMENDMENT DATE:

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FACULTY OF ENGINEERING TECHNOLOGY DEPARTMENT OF CIVIL ENGINEERING TECHNOLOGY

DEPARTMENT OF INFRASTRUCTURE AND GEOMATIC

ENGINEERING

LABORATORY INSTRUCTION SHEETS

COURSE CODE

EXPERIMENT NO. MG02

EXPERIMENT TITLE Levelling (Establish TBM) DATE

GROUP NO.

LECTURER/ INSTRUCTOR/ TUTOR 1)₂₎ DATE OF REPORT SUBMISSION

DISTRIBUTION OF MARKS FOR LABORATORY REPORT

ATTENDANCE/PARTICIPATION/DISPLINE /5%

INTRODUCTION: /5%

PROCEDURE: /5%

RESULTS & CALCULATIONS /15%

ANALYSIS /15%

DISCUSSIONS: /20%

ADDITIONAL QUESTIONS: /15%

CONCLUSION: /10%

SUGGESTION & RECOMENDATIONS /5%

REFERENCES: /5%

TOTAL: /100%

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TECHNOLOGY EDITION:

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STUDENT CODE OF ETHICS

DEPARTMENT OF CIVIL ENGINEERING TECHNOLOGY

FACULTY OF ENGINEERING TECHNOLOGY

I hereby declare that I have prepared this report with my own efforts. I also admit to

not accept or provide any assistance in preparing this report and anything that is in it is true.

1) Group Leader __________________________________________(Signature) Name : __________________________________

Matrix No. : __________________________________

2) Group Member 1 __________________________________________(Signature) Name : __________________________________

Matrix No : ___________________________________

3) Group Member 2 __________________________________________(Signature) Name : __________________________________

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TECHNOLOGY EDITION:

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1.0 INTRODUCTION :

Vertical Control in the general terms applied to say of the various processes each elevation of by points or differences in the elevation are determined. It is vital operation in producing necessary data for mapping, engineering design, and construction.

2.0 AIM :

To fly reduced level from known point (Benchmark or Temporary Benchmark) to unknown point.

3.0 EQUIPMENTS :

8.1 Level and Tripod (1 set) 8.2 Staff (2 sets)

8.3 Staff bubble (2 sets)

4.0 FIELD PROCEDURES :

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9.1.1 A series of measurements of level loop were considered as shown in figure 3.3 9.1.2 BM A was started first, so the first reading measurement from Setup 1 was a back sight to BM A, and the second reading was a foresight to CP1 known as a change Point. 9.1.3 The levelling staff then remains at CP1, while the instruments were moved to Setup 2. The sight reading to CP1 and foresight reading to CP2 and so on were taken.

9.1.4 Eventually, a Setup 4, a back sight reading was made to CP3, and foresight reading to A.

9.1.5 The traverse was then closed. This allows a check on the levels, since the sum of total loop changes in level should be zero.

9.2

Booking Procedures

9.2.1 The Rise and Fall Method

The terms that are commonly used in the Rise and Fall Method are:

BS = Back sight FS = Foresight

IS == Intermediate Sight, and RL = Reduced Level

9.3 Reduction (Calculation) Procedures

9.3.1 The surveys accuracy was checked and should be within tolerances given below or suitable for the project. This check should be applied before one leaves the job.

9.3.2 The following check the arithmetic of one’s level reductions and must be exact: ∑BS - ∑FS = ∑Rise - ∑Fall

(BS) – (FS) = RL (last BM) – RL (start BM)

2 Figure 3.3: A sample of leveling loop

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9.3.3 Misclosure should be:

±(20√K) mm, where K is the length of the traverse in km.

9.3.4 For example, misclosure is +30mm and the length of the loop is 0.7 km. Hence the misclosure limit is 20√0.7 = ±17 mm. Therefore, the misclosure of +30 mm is too big (means that the levelling work is not accepted).

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6.0 CALCULATION : 4 R E M A R K S B M 2= 2. 00 0 C P 1 C P 2 C P 3 C P 4 T B M 2 C P 5 C P 6 C P 7 C P 8 B M 2= 2. 00 0 D IS T 7 ₃₀ ₃₀ ₄₀ ₂₀ ₂₀ ₄₀ ₃₀ ₃₀ 7 A D JU ST E D R L 2. 00 0 1. 99 3 2. 00 4 2. 10 7 1. 99 5 2. 07 0 1. 99 5 1. 93 0 2. 05 7 2. 03 6 2. 00 0 C O R R E C T IO N 0 0 0 0 0 0 0 0 0 0 0 R E D U C E D L E V E L 2. 00 0 1. 99 3 2. 00 4 2. 10 7 1. 99 5 2. 07 0 1. 99 5 1. 93 0 2. 05 7 2. 03 6 2. 00 0 H oC FA L L 0. 00 7 0. 11 2 0. 07 5 0. 06 5 0. 02 1 0. 03 6 R IS E 0. 01 1 0. 10 3 0. 07 5 0. 12 7 F S 1. 38 3 1. 37 5 1. 28 2 1. 40 0 1. 32 0 1. 39 5 1. 32 8 1. 29 0 1. 30 6 1. 42 8 T = 13 .5 07 IS 0. 00 0 B S 1. 37 6 1. 38 6 1. 38 5 1. 28 8 1. 39 5 1. 32 0 1. 26 3 1. 41 7 1. 28 5 1. 39 2 T = 13 .5 07

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Misclosure = ± (20

√

k ) = 20

√

0.254 = 10.07. Total distance = 127 m K = Total distance × 2 = 127 × 2 = 254 m.

Arithmetic checks ( necessary for checking the reduction )

∑

(_{BS) -}

∑

(_{FS) = 13.507 km – 13.507 km = 0 km}

∑

(_{RISE) -}

∑

(_{FALL) = 0.316 km – 0.316 km = 0 km}

LAST (RL) – FIRST ( RL) = 2.000 m – 2.000 m = 0 (ok)

7.0 DISCUSSION

During the process of levelling, precaution that needs to be considered while carrying out the levelling includes,

 The tripod must be in the stable state and the bubble at the level must be in the centre.

 While reading the measurements, make sure that the crosshair are visible.  Put a nail below the staff for more precise readings.

 Put the level in its case before move to the next point.

The reading obtained did not contain any error. Therefore, the misclosure of the reading is checked by calculating the limit of misclosure allowed.The formula of misclosure limit was

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given by ±(20 √ D)mm , where D= length of traverse in km. The length of traverse of our set up was 0.254km. The misclosure allowed is ±10.07mm. The reading is acceptable.

The route we used for the levelling was from BM2 to TBM 2 and then back to BM 2. We had marked down the spot we set up the levelling equipment and also the stuffs to make sure that the reading obtained are more accurate.

8.0 CONCLUSION

The value of the misclosure that is 254 m indicates that our has been able to carry out the

levelling with a good accuracy and the value of

∑

(BS) -

∑

(FS) has been found as 0 km.

9.0 REFERENCES

http://www.levelling.uhi.ac.uk/tutorial1_9.html

W.SCHOFIELD , 2007 , Engineering Surveying , 6th Edition . Butterworth – Heinemann : Linacre House , Jordan Hill , Oxford OX 2 8DP , UK.