Page 83 - Buried Pipe Design
P. 83
External Loads 59
2 ft
105 in
q
Figure 2.31 Sketch of 105-in-diameter buried pipe with water table at the soil surface.
Sketch shows acting vertical forces—the buoyant force, the effective soil resistance, and
the pipe weight. The pipe is empty.
Soil:
d 110 pcf dry unit weight of soil
e 0.52 void ratio
w
b 69.0 pcf d
1 e
23° soil friction angle from lab tests
f 56.5° soil slip angle 45°
2
H 3.0 ft soil cover
(1 e) 110
G 2.68 specific gravity of soil grains
62.4
The specific gravity of most soil is in the range of 2.65 to 2.7.
Will the pipe float? To calculate, first find the volume of the soil wedge per
foot of pipe. This is the area of the soil wedge in Fig. 2.31.
Total area A 2 (A 1 A 2 A 3 A 4 )
hR
A 1 hR
tan
1 1 hh 1 h 2
A 2 hb 2
2 2 tan 2 tan
1 R 2
A 3
2 tan
