SURVEYING 1 CE 215 CHAPTER -3-

Transcription

1 Civil Engineering Department SURVEYING 1 CE 215 CHAPTER -3- PROFILE AND CROSS SECTION LEVELING 1 2 1

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20 Example -1- The notes of profile leveling are recorded in a level note book where backsights, intermediate sights and foresights are placed in independent columns. The stations of points are noted in separate columns, Staff readings are also taken at salient points where marked changes in slope occur, such as that at X. 1. Reduce the levels by the height of instrument and (rise and fall ) methods and apply appropriate checks. 2. Draw the design line at the proposed grade. If you know a uniform downward gradient of 0.2 in 10 starts at point 1, having elevation of 107 m, then a uniform upward gradient of 0.1 in 10 starts at point X. 3. Find slope or (gradient) or (percentage grade) for the designed lines. 4. Plot cross section at station Compute the values of the height of embankment and depth of cutting. 39 Profile readings Cross-section readings at station Points Stations A Staff Reading (m) B.S I.S F.S B X C Points Station Staff reading (m) Remark B.S. I.S. F.S m m left m left m left m right m right m right B T.P.1 : 40 20

21 PROFILE (LONGITUDINAL SECTION) Solution 41 Solution ; 1. Reduce the levels by the height of instrument (rise and fall ) methods and apply appropriate checks. Difference in Staff Reading (m) Points Station Elevation (m) H.I (m) R.L(m) Remarks B.S I.S F.S Rise Fall A B.M B T.P X C

22 Solution ; 43 Solution ; Stations Distance (m) N.G.L (m) Grade Elev. (m) CUT (+) FILL (-)

23 Drawing Profile Graph Drawing Profile graph by using a software application (Microsoft Excel). Manually draw a profile and compute earthwork: Assume the horizontal axis is the distance and the vertical axis is the elevation. Use a larger scale for the elevation than the distance scale, usually 10 times larger. Draw the design line at the proposed grade. Compute the areas of cut and fill. Multiply area by width to get volumes. Gradient (percent grade) is the rise or fall in ft per 100 ft, or meter per 100 meter. 45 Plotting of profile leveling Provides a graphical representation of the ground points on a longitudinal section along the alignment. It is being used to determine the depth of cutting or filling on the proposed gradient (for highways, railways, canals, etc.), to study grade crossing problems, to select appropriate grade, to locate depth of sewer, tunnels etc. In this, a datum line is drawn along which distance of the stakes are marked and reduced levels are plotted along vertical lines drawn on the marked points. Segmented straight lines joining the reduced level points represent the longitudinal profile of the ground surface. Profile is generally drawn so that the vertical scale is much larger than the horizontal scale in order to accentuate the differences of elevations. Slope Line 1= [ (Grade Elevation last Grade Elevation first ) / Distance between them ]*100 S1= [( )/55]*100 S1= -2.18% S2= [( )/45]*100 S1= +1.11% 46 23

24 Elevation (m) ELEVATION (m) 9/27/2017 Profile (Longitudinal ) Section N.G.L (m) Grade Elevation (m) % +1.11% Distance (m) 47 N.G.L (m) Grade Elevation (m) DISTANCE (m) 48 24

25 CROSS-SECTION Solution 49 Solution ; Points Station Staff reading (m) Difference in elevation (m) B.S. I.S. F.S. Rise (m) Fall (m) H.I (m) R.L (m) Remark m m left m left m left m right m right m right B T.P. 1 : 50 25

26 51 ASSIGNMENT 1; Group -1- Following staff readings were taken with a level. The instrument have been shifted after the 4th, 7th and 10th reading. R.L. of the starting B.M. is m. Enter the reading in the form of a level book page. Find the R.L. of stations and apply usual checks , 3.745, 3.830, 2.275, 2.645, 0.385,0.960, 1.640, 2.845, 3.845, and Reduce the levels by the height of instrument method and apply appropriate checks. 2. Draw the design line at the proposed grade. If you know a uniform upward gradient of 0.1 in 10 starts at point 1, having elevation of m. 3. Find slope or (gradient) or (percentage grade) for the designed line. 4. Compute the values of the height of embankment and depth of cutting

27 ASSIGNMENT 1; Group -2- Following staff readings were taken with a level. The instrument having been shifted after the 4th, 7th and 10th reading. R.L. of the starting B.M. is m. Enter the reading in the form of a level book page. Find the R.L. of stations and apply usual checks , 3.745, 3.830, 2.275, 2.645, 0.385,0.960, 1.640, 2.845, 3.845, and Reduce the levels by the height of instrument method and apply appropriate checks. 2. Draw the design line at the proposed grade. If you know a uniform downward gradient of 0.1 in 10 starts at point 1, having elevation of m. 3. Find slope or (gradient) or (percentage grade) for the designed line. 4. Compute the values of the height of embankment and depth of cutting.t 53 Group -1- Group (upward 0.1 in 10) 2. (upward 0.15 in 10) 3. (upward 0.2 in 10) 4. (upward 0.25 in 10) 5. (upward 0.3 in 10) 6. (upward 0.35 in 10) 7. (upward 0.4 in 10) 8. (upward 0.45 in 10) 9. (upward 0.5 in 10) 1. (downward 0.1 in 10) 2. (downward 0.15 in 10) 3. (downward 0.2 in 10) 4. (downward 0.25 in 10) 5. (downward 0.3 in 10) 6. (downward 0.35 in 10) 7. (downward 0.4 in 10) 8. (downward 0.45 in 10) 9. (downward 0.5 in 10) 54 27

28 Note ; This assignment should be plotted by Microsoft Office - Excel Program. Deadline is the following week. 3% on your total mark