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<< Click to Display Table of Contents >> Calculations |
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The following calculations are used in this test:
Deformation
The lateral and axial deformations can be specified directly or using deformation dial readings. When using dial readings they are converted to actual deformations using a dial constant.
DL = (RLi - RL) * LDC Lateral Deformation
DA = (RA - RAi) * ADC Axial Deformation
where,
DL = Lateral deformation
DA = Axial deformation
RL = Lateral dial reading
RLi = Initial lateral dial reading
LDC = Lateral dial constant
RA = Axial dial reading
RAi = Initial axial dial reading
ADC = Axial dial constant
Axial Load
The axial loads can be specified directly or using readings from a load ring. When using readings from a load ring the readings are converted to axial loads either using load ring constants or a linear equation.
Load Ring Constant
If R < Crossover P = R * LRC1
If R > Crossover P = Crossover * LRC1 + (R - Crossover) * LRC2
Linear
P = M * R + C
where,
P = Axial load
R = Axial dial reading
LRC1 = Load ring constant 1
LRC2 = Load ring constant 2
M = Linear multiplier
C = Linear constant
Axial Strain
εa = (DA - DA0) / h
where,
εa = Axial strain
DA = Axial deformation
DA0 = Initial axial deformation (first deformation)
h = Sample height
Lateral Strain
εl = (DL - DL0) / d Diameter lateral strain method
εl = ((DL/π) - DL0) / (d/π) Circumference lateral strain method
where,
εl = Lateral strain
DL = Lateral deformation
DL0 = Initial lateral deformation (first deformation)
d = Sample diameter
Deviator Stress
σd = P / A
where,
σd = Deviator stress
P = Axial load
A = Sample cross-sectional area
Minor Stress
σ3 = CP
where,
σ3 = Minor stress
Cp = Confining pressure
Major Stress
σ1 = σd + σ3
where,
σ1 = Major stress
Compressive Strength
Compressive strength = maximum σd
Water Content
wi (%) = 100 * (Mbwt - Mbdt) / (Mbdt - Mbt)
where,
wi = Initial percentage water content
Mwt = Mass of tare and wet specimen
Mdt = Mass of tare and dry specimen
Mt = Mass of tare
Dry Density
ρd = Mw / V / (1+ w)
where,
ρd = Dry density
Mw = Wet sample mass
V = Sample volume
w = Water content
Dry Unit Weight
γd = ρd * γw
where,
γd = Dry unit weight
γw = Unit weight of water (9.807 kN/m3)
Saturation
Si (%) = 100 * Vwi / Vvi
where,
Si = Initial saturation
Vwi = Initial volume of water in sample = (Mw - Ms) / ρw
Vvi = Initial volume of voids = Vi - Vs
Vs = Volume of solids = Ms / (SG * ρw)
Ms = Mass of solids = Mw / (1 + wi / 100)
ρw = Density of water (1.0 g/cm3)
SG = Specific gravity
Void Ratio
ei = Vvi / Vs
where,
ei = Initial void ratio