Analytical Report: Precision and Fitness for Purpose
The long sections' calculations generated a uniform alignment of the drain between points A and H with an Xm value of 7.97m. The drain begins at a depth of 0.50 m below the ground surface and gradually grows towards the outlet to about 7.97 m. The gradient of about 1:9 calculated gives a constant fall, which is efficient in the movement of gravity. Surface reduced levels fade slowly between 500.000 m at point A to 498.700 m at point H, which implies the existence of a real ground profile, and the drain invert levels are realistically modelled.
Nonetheless, the enormous rise in the depth of excavations to the outlet can lead to some viable construction difficulties and must be checked by more accurate measurements. Levelling errors, including instrument calibration, inaccuracy in reading of the staff, and misclosure, may also influence the accuracy of the obtained results. Accuracy would be enhanced by repetitive observations and correction of errors. In general, the findings are appropriate to the initial design but need to be improved for the final construction setting out.
Point | Chainage | Surface RL (m) | Gradiant drain line/ Drain Invert RL (m) | Depth to dig (m) | |||||
A | 0 | 500 | 499.5 | 0.5 | Student ID Last digits | 97 | |||
B | 10 | 499.82 | 498.247619 | 1.572380952 | |||||
C | 20 | 499.65 | 496.9952381 | 2.654761905 | XM value | 7.966666667 | |||
D | 30 | 499.43 | 495.7428571 | 3.687142857 | |||||
E | 40 | 499.2 | 494.4904762 | 4.70952381 | |||||
F | 50 | 499.05 | 493.2380952 | 5.811904762 | Start invert RL | 499.5 | |||
G | 60 | 498.9 | 491.9857143 | 6.914285714 | |||||
H | 70 | 498.7 | 490.7333333 | 7.966666667 | |||||
End Invert RL | 490.7333333 | ||||||||
Gradient | -0.125238095 | ||||||||
Note: Drain gradient calculated using linear interpolation between the start and end invert levels. Absolute cell referencing was used to maintain consistency of the calculations. | |||||||||
Start Depth | 0.5 | ||||||||
End Depth (Xm) | 7.97 | ||||||||
Total Length | 78.93 | ||||||||
Total Fall | 8.77 | ||||||||
Gradient | 9 | ||||||||
Point | Chainage | Surface RL (m) | Gradiant drain line/ Drain Invert RL (m) | Depth to dig (m) | |||||
A | 0 | 500 | 499.5 | 0.5 | Student ID Last digits | 97 | |||
B | 10 | 499.82 | 498.247619 | 1.572380952 | |||||
C | 20 | 499.65 | 496.9952381 | 2.654761905 | XM value | 7.966666667 | |||
D | 30 | 499.43 | 495.7428571 | 3.687142857 | |||||
E | 40 | 499.2 | 494.4904762 | 4.70952381 | |||||
F | 50 | 499.05 | 493.2380952 | 5.811904762 | Start invert RL | 499.5 | |||
G | 60 | 498.9 | 491.9857143 | 6.914285714 | |||||
H | 70 | 498.7 | 490.7333333 | 7.966666667 | |||||
End Invert RL | 490.7333333 | ||||||||
Gradient | -0.125238095 | ||||||||
Note: Drain gradient calculated using linear interpolation between the start and end invert levels. Absolute cell referencing was used to maintain consistency of the calculations. | |||||||||
Start Depth | 0.5 | ||||||||
End Depth (Xm) | 7.97 | ||||||||
Total Length | 78.93 | ||||||||
Total Fall | 8.77 | ||||||||
Gradient | 9 | ||||||||
BUILDER INSTRUCTION NOTES
Drain to be excavated from Point A to Point H
Total Length = 78.93 m
Drain starts at 0.50 m below ground at Point A
Drain finishes at 7.97 m below ground at Point H
Design Gradient = 1 : 9 (uniform fall)
Total Fall = 8.77 m
Reduced Level at A = 500.000 m
Reduced Level at H = 498.700 m
Misclosure = -0.091 m (within acceptable tolerance)
All depths measured vertically from the existing ground level.
