Page 34 - Buried Pipe Design

12 Chapter Two

h V

gB dh
d
V
Ku dh
H dh B d

V
K
B d
V dV

B d

B c

Figure 2.1 Basis for Marston’s theory of loads on buried pipe. W d load
on conduit per unit length along conduit in pounds per linear foot; e
base of natural logarithms; unit weight of backfill, i.e., pounds per
cubic foot; V vertical pressure on any horizontal plane in backfill, in
pounds per unit length of ditch; B c horizontal breadth (outside) of
conduit, in feet; B d horizontal width of ditch at top of conduit, in feet;
H height of fill above top of conduit, in feet; h distance from ground
surface down to any horizontal plane in backfill, in feet; C d load coef-
ficient for ditch conduits; tan coefficient of internal friction of
backfill; ′ tan coefficient of friction between backfill and sides
of ditch; K ratio of active lateral unit pressure to vertical unit pres-
sure. (Reprinted, by permission, from Spangler and Handy, Soil
Engineering, 4th ed., Harper & Row, 1982.)