fundamentals of engineering supplied-reference handbook - Ventech!

GEOTECHNICAL
Definitions
c = cohesion
qu = unconfined compressive strength = 2c
Dr = relative density (%)
= [(emax – e)/(emax – emin)] ×100
= [(1/γmin – 1/γ) /(1/γmin – 1/γmax)] × 100
emax = maximum void ratio
emin = minimum void ratio
γmax = maximum dry unit weight
γmin = minimum dry unit weight
τ = general shear strength = c + σtan φ
φ = angle of internal friction
σ = normal stress = P/A
P = force
A = area
σ′ = effective stress = σ – u
σ = total normal stress
u = pore water pressure
Cc = coefficient of curvature of gradation
= (D30) 2 /[(D60)(D10)]
D10, D30, D60 = particle diameters corresponding to 10%
30%, and 60% finer on grain-size curve
Cu = uniformity coefficient = D60 /D10
e = void ratio = Vv/Vs
Vv = volume of voids
Vs = volume of solids
w = water content (%) = (Ww/Ws) ×100
Ww = weight of water
Ws = weight of solids
Wt = total weight
Gs = specific gravity of solids = Ws /(Vsγw)
γw = unit weight of water (62.4 lb/ft 3 or 1,000 kg/m 3 )
PI = plasticity index = LL – PL
LL = liquid limit
PL = plastic limit
S = degree of saturation (%) = (Vw/Vv) × 100
Vw = volume of water
Vv = volume of voids
Vt = total volume
γt = total unit weight of soil = Wt/Vt
γd = dry unit weight of soil = Ws/Vt
= Gsγw/(1 + e) = γ /(1 + w)
Gsw = Se
γs = unit weight of solids = Ws / Vs
n = porosity = Vv/Vt = e/(1 + e)
CIVIL ENGINEERING
111
qult = ultimate bearing capacity
= cNc + γDf Nq + 0.5γBNγ
Nc, Nq, and Nγ = bearing capacity factors
B = width of strip footing
= depth of footing below surface of ground
Df
k = coefficient of permeability = hydraulic conductivity
= Q/(iA) (from Darcy's equation)
Q = discharge flow rate
i = hydraulic gradient = dH/dx
A = cross-sectional area
Q = kH(Nf/Nd) (for flow nets, Q per unit width)
H = total hydraulic head (potential)
Nf = number of flow channels
Nd = number of potential drops
Cc = compression index = ∆e/∆log p
= (e1 – e2)/(log p2 – log p1)
= 0.009 (LL – 10) for normally consolidated clay
e1 and e2 = void ratios
p1 and p2 = pressures
∆H = settlement = H [Cc /(1 + e0)] log [(σ0 + ∆p)/σ0]
= H∆e/(1 + e0)
H = thickness of soil layer
∆e, ∆p = change in void ratio, change in pressure
e0, σ0 = initial void ratio, initial pressure
cv = coefficient of consolidation = THdr 2 /t
T = time factor
t = consolidation time
Hdr = length of drainage path
Ka = Rankine active lateral pressure coefficient
= tan 2 (45 – φ/2)
Kp = Rankine passive lateral pressure coefficient
= tan 2 (45 + φ/2)
Pa = active resultant force = 0.5γH 2 Ka
H = height of wall
FS = factor of safety against sliding (slope stability)
cL + Wcosα
tanφ
=
W sinα
L = length of slip plane
α = slope of slip plane with horizontal
φ = angle of internal friction
W = total weight of soil above slip plane