#Jameel_Academy_Soil_Test

1. University of Duhok
College of Engineering
Civil Department
Soil Mechanics – Practical
Soil Laboratory
A Report About :
Consolidation Test
Submitted By : Jameel Masoud
Lab. No. : 4
Group Name : B
Testing Date : 22 / 4 / 2019
Submitting Date : 7 / 5 / 2019
Supervised By : Hussein
2018 – 2019

2. Introduction
When soil is loaded undrained, the pore pressures increase. Then, under site conditions,
the excess pore pressures dissipate and water leaves the soil, resulting in consolidation
settlement. This process takes time, and the rate of settlement decreases over time.
Consolidation is gradual reduction in volume, on load application, of a fully saturated
clay due to drainage of pore water. It continues until all the excess pore pressure
generated by the increase in total stress has completely dissipated.
Purpose:
The consolidation test is used to determine the compression index Cc, which indicates
the compressibility of the specimen, swelling index Cs, and pre-consolidated pressure
p`, which define the soil compressibility, the coefficient of consolidation Cv, which
characterize the rate of primary compression and the secondary compression
coefficient Ca, which define the creep properties
Supplies and materials for Consolidation Test:
1) Consolidation loading device.
2) Consolidation cell:
- Fixed ring.
- cell body and base water tight.
- Consolidation ring retainer and fixing screws or nuts.
- Loading cap.
- Two porous discs.
3) one Dial gauge.
4) Specimen trimmer and accessories.
5) Balance, Drying oven, Timer, Moisture content cans

3. Sketch :
Fixing Ring Floating Ring
Consolidation Loading Device

4. Test Procedure :
1) Weigh and measure the diameter of consolidation ring.
2) Cut and trim specimen into ring. Determine water content and specific gravity
from trimmings.
3) Weigh specimen in ring and measure the initial height (Hi) of the specimen
4) Place bottom porous stone into the consolidation cell
5) Put filter paper on top of the porous stone
6) Place consolidation ring with sample on top of the filter paper
7) Put another filter paper on top of the sample
8) Place the top porous stone on top of the filter paper
9) Assemble specimen in consolidation cell
10) Fit cell in the load frame and set up loading yoke
11) Set the vertical displacement dial so that its full range is available during
compression.
12) Apply the first increment of load
13) Take dial reading at exactly 0,0.25,0.5,1,2,4,8,15,30,60 and 120 min then say
4,8 and 24 hr of elapsed time.
14) After 24 hr change the load to the next value and take readings at the same
elapsed time intervals as before
15) The typical load sequence as follows: 25, 50,100, 200, 400, 800, 1600 (and
sometimes 3200) kPa.
16) Repeat the procedure before until all loading steps are completed
17) The load is decreased to 4 Kg (2Kg/cm2) and then to 1/4 Kg ( 1/2 Kg /cm2 )
rebound loads ; no time readings are normally taken during the rebound (
unloading )
18) Quickly dismantle the consolidometer cell and weigh the wet sample
19) Dry the specimen in the oven and measure its weigh of solids Ws.

5. Calculation:
For Example : Reading is 32, Load = 25 kPa, Time @90 min = 10
For a given sample:
Hs = 10.84 mm, H = 20 mm, eo = 0.845 Accuracy =10−2
mm
Sol :
∆H = (32 − 0) × 10−2
= 0.32mm , ∆e =
∆H
Hs
=
0.32
10.84
= 0.03
e @ 25 kPa = 0.845 − 0.03 = 0.815
Haverage = 20 −
19.680+20
2
= 19.840 mm ,Hd =
Haverage
2
= 9.92 mm
Cv =
Tv @90 min×Hd
2
Time @ 90 min
=
0.848×9.922
10
= 8.345 mm2
min⁄ = 0.083 cm2
min⁄
av =
∆e
∆P
=
0.03
25
= 0.0012 m2
N⁄
mv =
av
1+eo
=
0.001
1+0.845
= 0.006
 Complete Calculation shown in next paper as a table:

6. Discussion and Conclusion:
In this test we determine the Consolidation of our sample of soil by using the loading
consolidation apparatus, finally we get a result after doing all procedure accurate which
gave us Consolidation with changing in load magnitude, we know that Cv, av and mv
are the consolidation parameter which are used for determining the primary and
secondary settlement and it gave an idea about permeability coefficient of soil. In
consolidation test we have many factor that affect the result which is the drainage
condition, Soil type, Permeability of soil and dispersion of sample…etc. the error that
may happen during the test is the fully saturation of sample because while in testing the
sample and Appling load, it should fully saturate the sample, and another one is not level
of loading apparatus, or missing of filter paper.
In conclusion the purpose of this test is to determine the Consolidation parameter of soil
sample, using it in computing of consolidation settlement and determining the
permeability coefficient. Therefore, determining the consolidation parameter is the
important thing that must be performed during any important project that want high
construction quality.