SEMI FINALS Flashcards
Total Settlement of Foundation
Sᴛ = Sc + Ss + Se
Normally Consolidated Clay in Primary Consolidated Settlement
Sc = (CcH / 1+eᴏ) log ((Po+ΔP)/Po)
Increase in Vertical Pressure
ΔP = (Pᴛ + 4Pᴍ + Pʙ) / 6
P formula for Vertical Pressure
P = Applied Load (P) / Area
Over-Consolidated Clay when Po + ΔP < Pc
Sc = (CsH / (1+eo)) log ((Po+ΔP) / Po)
Over-Consolidated Clay when Po + ΔP > Pc
Sc = (CsH)/(1+eo) log (Pc/Po) + (CcH)/(1+eo) log (Po+ΔP)/Pc
Secondary Settlement
Ss = Ca’H log (t2/t1)
Ca’ Formula
Ca’ = Ca / (1+ep)
Secondary Compression Index
Ca = Δe / log(t2/t1)
Void ratio at the end of primary settlement
ep = eo - Δe
Change in void ratio
Δe = Cc log ((Po+ΔP)/Po)
Compression Index
Cc = 0.009 (LL - 10)
Liquid Limit Formulas
PI = LL-PL
LI = (ω-PL)/(LL-PL)
Swell Index
Ranges from 1/5 to 1/10 of Cc
Sᴛ
Total Settlement
Sc
Primary Consolidation Settlement
Ss
Secondary Consolidation Settlement
Se
Immediate Settlement
Cc
Compression Index
eo
In situ void ratio
Po
Average Effective Stress at the Middle of Clay Layer
ΔP
Average Increase of Effective Stress on Clay Layer
H
Thickness of Clay Layer
Pᴛ
Pressure at top
Pᴍ
Pressure at Middle
Pʙ
Pressure at Bottom
Cs
Swell Index
Pc
Pre-Consolidation Pressure
LL
Liquid Limit
PI
Plastic Index
PL
Plastic Limit
LL
Liquidity Limit
t1
Time for completion of Primary Settlement
t2
Time after completion of Primary Settlement
Ca
Secondary Compression Index
ep
Void ratio at the end of primary settlement
Δe
change in void ratio
eo
In situ void ratio
The total vertical displacement that occur at foundation level
Total Settlement
is a process of dissipation of increased pore water pressure due to the application of loads on the soil layer and increases in the effective stress in the soil skeleton. This results in a volumetric change in the soil skeleton.
Primary Consolidation
is the continued deformation of the soil structure after excess pore pressure has dissipated, such as the sliding of particles over each other or compression of particles.
Secondary Consolidation
occurs straight away as soon as the load is applied to the soil and and involves reduction in void space and rearrangements of the soil particles in response to that load
Immediate Settlement
Clay that is compacted by exactly the amount to be expected from the pressure exerted by the overburden; clay which has never been overloaded.
currently experiencing the maximum vertical overburden effective pressure they have ever experienced in their history.
Normally Consolidated Clay
Clay soil deposit that has been fully consolidated under a pressure
Over-consolidated clay
it is measured as the slope of the curve between void ratio and effective stress.
Compression Index
is evaluated based on laboratory measurements on high-quality, “undisturbed” samples of soil.
In situ void ratio
the slope of the rebound curve of void ratio versus the logarithm of the effective pressure curveis used to estimate the consolidation settlement of over-consolidated fine grained soils.
Swell Index
