Consolidation Test of soil complete report including graphs, DiscussionDescripción completa
Consolidation
Consolidation of soils Soil Mechanics
consolidation lab report
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Soil
Carter & BentleyDescripción completa
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How anyone can take a portion of their yard and turn it into a garden that will provide you all the food you need to substain your life right outside your doorDescripción completa
This book describes the calculation of soil settlement for shallow foundations as per IS criterion.
This paper is a learning tool addressing soil resistivity consisting of an introduction to electrical resistivity, a brief history, the fundamentals of soil resistivity, data graphing, inter…Full description
When soil is loaded to a stress level greate greaterr than it ever ‘experienced’ in the past, the soil structure is no longer able to sustain the increased load, and start to breakdown breakdown..
Preconsol Preconsolidat idation ion Pressure Pressure - Pc:
e o i t a r d i o V
Maximum pressure experienced by soil in the past Pc
Normal Consolidation: OCR = 1
Pc p’ o
Over Consolidation: Consolidation: OCR > 1
when the preconsolidation pressure is equal to the existing effective vertical overburden pressure Pc = p’ o present effective overburden pressure is the maximum pressure that soil has been subjected in the past
Effective Consolidation Stress p’ o
when the preconsolidation pressure is greater than the existing effective vertical overburden pressure Pc > p’ o present effective overburden pressure is less than that which soil has been subjected in the past It also said soil is in preconsolidated condition OCR (over consolidation ratio) =
Under Consolidation: Consolidation: OCR < 1
Pc = p’ o Pc p’ o Pc > p’ o
Pc p 'o
when the preconsolidation pressure is less than the existing effective vertical overburden pressure Pc < p’ o, e.g : recently deposited soil geologically or manually.
Effective Consolidation Pressure, p (log scale) Stress p’o
1 00
Settlement Calculation
(cont’d):
For normally consolidated clay Sc = Cc
Ho
1 + eo
log
Sc = Cce H o log
p'o + ∆ p
or
p 'o
when computing settlement using percentage vertical strain vs log effective pressure
p 'o + ∆p p 'o
p’ 1 = p’ o, and p’ 2 include the additional stress ∆p applied by the structure
For layered normally consolidated clay: ' Sc = C c o log o + 1 ' e p o o
∑
In overconsolidated clay Sc = C r
Ho
1+ eo
Ho
1 + eo
Sc = Cr
Cr is
log
log
p'o + ∆ p
p’ 1 = p’ o, and p’ 2 =po+∆p < Pc
p 'o
P c
Ho
p 'o
1 + eo
+ C c
log
p'o + ∆ p p 'o
the slope of rebound curve (swell index); Cr ≈ 20% to 10% Cc
p’ 1 = p’ o, and p’ 2 =po+∆p > Pc
Time Rate of Consolidation U t =
St S
for t U= 0 to 60%, for t > U 60%, Tv = cv
tv
or t v =
π U t %
v
v
Tv H d2r
2
T= 4 100 =T1.781 − 0.933 log(100 −
%U)
H dr2 cv Ut = average degree of consolidation (%) St = settlement of the layer at time t S = ultim ultimate ate settlem settlement ent of the layer layer due to primar primary y consoli consolidat dation ion Tv = time factor Hdr = average longest drainage path during consolidation cv = coefficient of consolidation tv = time for consolidation
Example Surcharge = 50kPa
2m
5m
5m
Sand Ground water table 50% saturation an Gs=2.65, e=0.7
Clay Cc=0.45, eo=0.9 γ sat=15kPa
Rock
Calculate the settlement due to primary consolidation for 5m clay layer due to a surc ar e o a applied at the ground level. The clay is normally consolidated. Calculate the time rate of settlement when cv is given as 0.85m2 /yr
Solution
Calculation of Average effective Overburden Pressure (po)
γ sand
=
γ 'sand
γ 'clay
=
=γ =
=
'sat (sand ) − γ w
Gs ⋅ γ w + e ⋅ γ w
1+ e
− γ w =
( 2.65 − 1) ⋅ 9.81 1 + 0.7
( Gs − 1) γ w 1+ e
= 9.516kPa
'sat ( clay ) − γ w
So
p'o
1 + 0.7
Submerged unit weight of sand below the ground water table
=γ
9kPa = 15 − 9.81 = 5.19kPa
The moist unit weight of sand above the ground water table .65 + 0.5 ⋅ 0.7 ) ⋅ 9.8 9.81 Gs ⋅ γ w + Sr ⋅ e ⋅ γ w ( 2.65