112 CIVIL WORKS GUIDELINES FOR MICRO-HYDROPOWER IN NEPAL
DEFINITION OF SYMBOLS USED IN TABLE 7.2
htotal = Total head including surge.
i = Uphill ground slope (Figure 7.5). Note that
α
= Upstream penstock angle with respect to
i
may not always be equal to á
the horizontal.
Ka = Active soil pressure coefficient as follows:
β
= Downstream penstock angle with respect
Ka
=
cos i - cos2i - cos2θ
to the horizontal.
cos i + cos2i - cos2θ
γ=
γwater
γconcrete
γmasonary
γpipe material
γsoil
=
=
=
=
=
φ=
a=
d
dbig
dsmall
E
f
g
h1
h2
=
=
=
=
=
=
=
=
Unit weight in kN/m3
9.8 kN/m3
22 kN/m3
20 kN/m3
See Table 6.2
see Table 7.3
Soil angle of friction, see Table 7.3
Coefficient of linear expansion of pipe
(oc-1), see Table 6.2 in Chapter 6 where
is the symbol used
Pipe internal diameter (m)
Internal diameter of larger pipe in case of
reduction in pipe diameter.
Internal diameter of smaller pipe in case of
reduction in pipe diameter.
Young’s modulus of elasticity, see Table
6.2 in Chapter 6.
Coefficient of friction between pipe and
support piers.
acceleration due to gravity = 9.8 m/s2
Buried depth of block at the upstream face.
Buried depth of block at the downstream
face.
L1d
L1u
L2d
L2u
L4d
L4u
Q
t
t
W
Wp
Ww
= Half the distance from anchor block
centreline to the centreline of the first
downstream support pier (Figure 7.5).
= Half the distance from anchor block
centreline to the centreline of the first
upstream support pier (Figure 7.5).
= Distance between two consecutive support
piers downstream of the anchor block.
= Distance between two consecutive support
piers upstream of the anchor block.
= Distance from the anchor block centreline
to the downstream expansion joint (Figure
7.5).
= Distance from the anchor block centreline
to the upstream expansion joint (Figure
7.5).
= Flow in the penstock pipe (m3/s).
= Wall thickness of penstock (m).
= Maximum temperature change (°C) that
the pipe will experience after being fixed
at anchor blocks.
= Width of the anchor block in m.
= Weight of pipe in kN/m
= Π(d+t)t γpipe material
= Weight of water in kN/m
= (Pipe area in m2) x γwater