Page 108 - Trenchless Technology Piping Installation and Inspection

74 Cha pte r T w o

Maximum Existing Depth of
Required DR (d/t)
Pipe Ovality Pipe (Soil
Percentage Cover) (ft) E = 250,000 psi E = 400,000 psi
i i
2% 4'–10' DR57 DR66
11'–15' DR48 DR56
16'–20' DR42 DR49
21'–24' DR39 DR46
5% 4'–10' DR52 DR61
11'–15' DR44 DR52
16'–20' DR39 DR45
21'–24' DR36 DR42
10% 4'–10' DR45 DR52
11'–15' DR38 DR45
16'–20' DR33 DR39
21'–24' DR31 DR36
Gravity Pipe, Fully Deteriorated Condition

Designed by:
Checked by:
Date: 09/29/2009
Project name Design example—48 in. diameter
Location Anytown, U.S.
Client
Design Criteria
Pipe mean inside diameter (in.) 48.00 in.
Ovality (q) % 2 %
Pipe minimum inside diameter (in.) 47.04 in.
External water (H , ft above invert) 12.00 ft*
w
External water (H , ft above crown) 8.00 ft*
w
Depth of soil (H, ft above top of pipe) 16.00 ft
Soil modulus (E ) psi 1000 psi
s
Liner pipe flexural modulus (E) psi 250,000 psi
Liner pipe flexural strength (S) psi 4500 psi
Reduction to account for long-term effects (%) 50%
Soil density (w) lb/ft³ (Table 2.11) 120 pcf
Live load (concentrated) lb (p) 16,000 lb
Live load (distributed), (p) psf 0 psf
Distributed load width, (X) ft 8 ft
Distributed load length, (Y) ft 20 ft
Factor of safety, N 2.00
*Plus internal vacuum if applicable