MIDTERM Flashcards
Symbols meaning
ι = Hydraulic Gradient
h = loss of head from A to B
L = length of flow over A to B
V = discharge velocity
K = hydraulic conductivity or coefficient of permeability
q = Flow rate
A = cross sectional area
Vs = seepage Velocity
n = porosity
e = void ratio
Q = Volume of water collected
t = duration of water collected
h = constant head between inlet and outlet
a = area of standpipe
h1 h2 = heads
r1 = smaller
r2 = larger or away
D10= effective size
c = constant that varies from 10 to 50mm2
h = capillary rise in mm
Known as Darcy slope (determines quantity of Darcy flux or discharge)
vector gradient between 2 or more hydraulic head measurements over the length of the flow path
Hydraulic Gradient
is a measure of a given porous medium ability to permit fluid flow through its voids
Interconnected voids that permits water to pass through under gradient force.
Permeability
The ability of an aquifer to transmit water through its entire thickness
Transmissivity or transmissibility
Ground-water reservoir, underground layer of water-bearing permeable rock, rock fractures, or unconsolidated materials where groundwater can be extracted using a water well.
Aquifer
Is the rate of flow of water through porous medium per unit cross-sectional area.
Used to solve for coefficient of permeability
Discharge Velocity
Represents the average velocity of flowing groundwater within pores of a porous medium.
Actual velocity (?)
flow of water through soil
Seepage Velocity
Use to determine the coefficient of permeability of coarse-grained soil
Constant Head Test
Who made the Darcy’s Law or Darcy’s permeability of soil
Henry Darcy
Hydraulic Gradient formula
ι =h/L
Discharge Velocity Formula
V=K ι
V=Q/At
Q=AV
Flow Rate Formula
Q=K ι A
Seepage Velocity Formula
Vs=V/n
Porosity Formula
n=e/1+e
Constant Head formula
K=QL/Aht
Falling Head Test
K=(aL/At) ln (h1/h2)
Area formula
π/4 (D^2)
mm-m
cm-m
mm-cm
1/1000
1/100
1/10
Unconfined Aquifer Formula
Q ln (r1/r2) / π(h1^2 - h2^2)
Confined Aquifer formula
K= Q ln (r1/r2) / 2πt (h1-h2)
Transmissibility formula
K= Q ln (r1/r2) / 2π (z1-z2)
Total Stress Formula
σ =Σδ h
Pore water pressure formula
u=δ sat(h)
Effective Stress Formula
σ ‘=σ- u
Capillary Stress formula
c=S(δ w) (h)
Capillary Rise formula
h= c/eD10
Gamma dry
δ d= Gs δ w / 1+e
Gamma moist
(Gs+Se) δ w / 1+e
Gamma sat
δ sat= (Gs+e) δ w / 1+e
Porosity formula
e / 1+e
Describes how fast water flows through the soil voids.
Hydraulic Conductivity
Sponge term, ratio of volume of voids to the total volume of soil
Porosity
Ratio of empty spaces in soil
Void Ratio
Meaning of r
distance from test well to observation well
r1 is the nearest
Meaning of z
water level dropped, should be subtracted to height
z1 is for h1
Movement of pore water from lower elevation to higher elevation, experiencing upward pull
Capillary Rise
The pressure transmitted through particles’ contact with each other. (grain-to-grain interaction).
Deformation of soil.
Effective Stress
It is the pressure of grounwater or fluids in the pore space of rock
Pore Water Pressure
Have a layer of impenetrable rock or clay above them, usually deeper than unconfined aquifer
Confined Aquifer
Lie below the permeable layer of soil, being recharged by rainwater or snow melt.
Unconfined Aquifer
Used to determine the coefficient of permeability of sands/silts/clays
Falling Head Test
