บทที่ 3 การวัดระยะทาง 2

• 1. 11/23/2010 1 3 (Distance Measurement) Version 2 .. 3 Three Types of Distances - Vertical - Horizontal - Slope

2. 11/23/2010 2 , Slope, Vertical and Horizontal Distances Techniques of Distance Measurement (Pacing) (Odometer) (Stadia) (EDM [Electronic Distance Measurement]) (Subtense bar) (Taping) 3. 11/23/2010 3 5 Odometer Wheel Surveying, 4/E by Jack McCormac Copyright 2005 by John Wiley & Sons, Inc. All rights reserved. Figure 3.2 (p. 39) Subtense bar. (Courtesy of Leica, Inc., formerly Kern Instruments and Wild Heerbrugg Instruments.) (Subtense bar [Tacheometry]) 4. 11/23/2010 4 Surveying, 4/E by Jack McCormac Copyright 2005 by John Wiley & Sons, Inc. All rights reserved. Figure 3.3 (p. 40) Distance measurement with a subtense bar. (Subtense bar) Surveying, 4/E by Jack McCormac Copyright 2005 by John Wiley & Sons, Inc. All rights reserved. Figure 3.4 (p. 41) Stadia readings. (Stadia) 5. 11/23/2010 5 Surveying, 4/E by Jack McCormac Copyright 2005 by John Wiley & Sons, Inc. All rights reserved. Figure 3.7 (p. 44) WILD D12002 electronic distance measuring instrument. (Courtesy of Leica, Inc., formerly Kern Instruments and Wild Heerbrugg Instruments.) (EDM [Electronic Distance Measurement]) Error (x mm + y ppm) EDM Error (1 mm + 2 ppm) (5 mm + 5 ppm) Surveying, 4/E by Jack McCormac Copyright 2005 by John Wiley & Sons, Inc. All rights reserved. Figure 3.8 (p. 48) Woven tape. (Courtesy of Keuffel & Esser a Kiatos Company.) (Taping) 6. 11/23/2010 6 Distance Measurement by Taping Surveyors and Engineers Tapes (Steel Tapes) 1/4-3/8 30, 60, 100 150 Invar Tapes 65% 35% Lovar Tapes steel tapes invar tapes Cloth (or metallic) Tapes 5/8 Fiberglass Tapes metallic tapes Taping Equipment for Field Party Chaining pins or Taping pins Hand level Tension handles Clamp handles Pocket Thermometer Range poles Plumb bobs 7. 11/23/2010 7 Hand Level 14 Hand level This is the simplest type of hand level. It is useful for estimating slope & elevation changes. This instrument is called the Abney level. It can be used to measure slope, vertical angles and stadia distances. 8. 11/23/2010 8 Taping on Level Ground poles pin 0 Normal Tape: Adding Tape: 0 +1126768 = 68 + 0.60 = 68.60 Subtracting Tape: 1 0236768 = 68 - 0.40 = 67.60 9. 11/23/2010 9 Horizontal Taping Using Plumb Bobs At Both Ends of the Tape 30 10. 11/23/2010 10 () pin () 11. 11/23/2010 11 () 2 () pin 12. 11/23/2010 12 () pin () pin 13. 11/23/2010 13 () (30 * 3) + 8.426 = 98.426 pin Standard Conditions for Steel Tape Use (Metric) 30.000 m tape - = 20 C - = 50 Newtons (11.24lbs) 14. 11/23/2010 14 Horizontal Measurement on Sloping Ground Breaking Tape Method Slope Measurements breaking tape 15. 11/23/2010 15 Example 1 125.450 2 50 H=Lcosa = 125.450 Cos 250= 125.970 Proportional errors 30 29.9995 Constant errors 16. 11/23/2010 16 Example 2 220.450 30 30.003 Lc = (30.003x220.450)/30 = 220.472 Temperature correction 17. 11/23/2010 17 Example 3 220.450 32 30 20 0.000011 Ct = 0.000011 (32-20)220.450 = 0.029 Lc = 220.450+0.029 = 220.479 Tension correction 18. 11/23/2010 18 Example 4 220.450 50 25 4 .. 2100 . .. 20 Cp = (25 20) 220.450/(4x2100) = 0.131 Lc = 220.450 + 0.131 = 220.581 Sag correction W2 = w2L2 W = 2 ; w = 19. 11/23/2010 19 Example 5 220.450 50 0.04 25 50 4 20.450 Lc = 220.450-0.053-0.001 = 220.396 2 3 2 0.04 50 4 0.053 24 25 x Cs m x 2 3 2 0.04 20.450 0.001 24 25 x Cs m x 20. 11/23/2010 20 Example 6 30 20C 10 30.003 5 . . 0.04 ./ A B 7 . 9 AB () (C ) A-1 30.000 15 1-2 30.000 15 2-3 30.000 15.5 3-4 30.000 15.5 4-5 30.000 15.5 5-6 30.000 16 6-7 30.000 16 7-8 30.000 16 8-B 21.508 16.5 Example 6 () 8 = -0.308 30.003 30.000 0.026 30.000 Ct m 2 (7 10)261.508 0.008 5 10 2,000,000 Cp m x x 2 3 2 0.04 30 8 0.294 24 7 x Cs m x 2 3 2 0.04 21.508 0.014 24 7 x Cs m x 21. 11/23/2010 21 Example 6 () = -0.013 () (C ) A-1 30.000 15 0.0000116(15-20)30 -0.00174 1-2 30.000 15 0.0000116(15-20)30 -0.00174 2-3 30.000 15.5 0.0000116(15.5-20)30 -0.001566 3-4 30.000 15.5 0.0000116(15.5-20)30 -0.001566 4-5 30.000 15.5 0.0000116(15.5-20)30 -0.001566 5-6 30.000 16 0.0000116(16-20)30 -0.001392 6-7 30.000 16 0.0000116(16-20)30 -0.001392 7-8 30.000 16 0.0000116(16-20)30 -0.001392 8-B 21.508 16.5 0.0000116(16.5-20)30 -0.001218 Example 6 () AB 261.508+0.026+0.013-0.008-0.308 = 261.205 22. 11/23/2010 22 (Obstruction) (b) Ca = -b2/2L L b Example 7 30 0.43 Ca = -b2/2L = -(0.43)2/2(30) = -0.003 30-0.003 = 27.997 23. 11/23/2010 23 () Ch = -h2/2d A B L S d Ch u h Example 8 50 1:100 h = 50(1/100) = 0.5 = 0.52/(2x50)=-0.002 . = 50-0.002 = 49.998 . 24. 11/23/2010 24 Ce= L.h/R L = h = R = L h O B1 BA A1 R Example 9 50 10 . 16.7oC 262 2 5 50 12 . 14.5, 13.6, 13.6, 12.7, 11.8 13.6 . 1:100 0.908 . 0.0078 ./ .. 21x105 ./ .. . = 11.7 x 10-6 oC 22oC = 191.000 6.371 x 106 25. 11/23/2010 25 Example 9 () 1 2 3 4 5 6 50 50 50 50 50 12 P 14.5 13.6 13.6 12.7 11.8 13.6 . 22 22 22 22 22 22 oC h ( ) 0 0 0 0.50 0.50 0.50 Example 9 () W/dL = 0.908/(0.0078x5000) = 0.0233 cm2 (W= A.d.L, W , d , L ) ( 12 ) W12= (0.908/50)x12 = 0.218 . 26. 11/23/2010 26 Example 9 () 1 2 3 4 5 6 +0.004 +0.004 +0.004 +0.003 +0.002 +0.001 +0.003 +0.003 +0.003 +0.003 +0.003 +0.003 Sag -0.008 -0.009 -0.009 -0.011 -0.012 -0.000 Slope 0.000 0.000 0.000 -0.002 -0.002 -0.001 -0.000 -0.002 -0.002 -0.007 -0.009 +0.001 50.000 49.998 49.998 49.993 49.991 12.001 261.981 Example 9 () = (261.981x191.000)/6.371x106 = 261.973 27. 11/23/2010 27 Sources of Errors in Taping Sources of Errors in Taping () 28. 11/23/2010 28 Random Error Taping pin Baseline Stations and Offset Distances 29. 11/23/2010 29 Surveying, 4/E by Jack McCormac Copyright 2005 by John Wiley & Sons, Inc. All rights reserved. Surveying, 4/E by Jack McCormac Copyright 2005 by John Wiley & Sons, Inc. All rights reserved. 30. 11/23/2010 30 3