Soil Mechanics

1. CE6405 SOIL MECHANICS
V.Nageshwaran, M.E.,
Assistant Professor,
Department of Civil Engineering,
UCET

2. DETERMINATION OF INDEX PROPERTIES

3. INDEX PROPERTIES
 Water Content
 Specific Gravity
 Particle/Grain Size Distribution
 Consistency Index
 In-situ Density
 Density Index

4. DETERMINATION OF IN-SITU DENSITY, VOID
RATIO & DENSITY INDEX

5. SAND REPLACEMENT METHOD
 Equipment – Sand Pouring Apparatus (Sand Pouring Cylinder,
Pouring Cone, and Valve or Shutter), Calibrating Container, Tray
with Central Circular Hole, Chisel, Scoop and a Balance, etc.
 Calibration of Cylinder – Determination of Weight of Sand
required to Fill the Pouring Cone of the Cylinder.
 Determination of Bulk Density of Sand.
 Uniformly Graded, Dry, Clean Sand preferably passing a 600 µ
Sieve and retained on 300 µ IS Sieve is used in the Method.
 The Sand Pouring Cylinder, SPC is filled upto a Height of 1 cm
below the Top.
 Weigh the Initial Mass, M1.
 Place the SPC over a Plane
Surface and the Sand is allowed to
run out to fill the Cone available
Below the SPC.

6. CONT…
 No further Flow – Close the Valve
or Shutter of SPC.
 Collect and Weigh the Sand filled in
the Cone of SPC, M2.
 Refill the SPC with Sand used to fill
the Cone of SPC and Ensure the
Original Mass, M1.
 Mount the SPC centrally over the
Calibrating Container, CC.
 Allow the Sand to Run out of SPC
for a Volume equal to that of the
CC.
 No further Flow – Close the Valve
or Shutter of SPC.
 Weight the Mass of SPC with Sand
after Filling the CC, M3.
 Mass of Sand required to Fill the
CC, M’ = M1 – M3 – M2.

8. CONT…
 Refill all the Sand into the SPC once again.
 Measurement of Soil Density – Clean and Level the Site –
Place the Tray (with Central Circular Hole) over it.
 Excavate a test hole of a depth approximately equal to CC
in the field and collect the Soil in the tray.
 Weigh the Mass of Soil excavated, M.
 Place the SPC centrally on the hole of the tray and allow the
sand run out into the hole – no further movement of sand –
Close the Valve or Shutter.
 Weigh the SPC and remaining Sand, M4.
 Mass of Sand Filling the hole, M’’ = = M1 – M2 – M4.
CC
'
Sand
V
M
ρ 
Sand
''
SoilExc.
ρ
M
V 

9. CONT…
 Bulk Density of Excavated Soil.
 Dry Density – Excavated Soil – Determine Water Content,
w.
w1
ρ
ρ
Soil)(Exc.
Soil)(Exc.d


SoilExc.
SoilExc.
V
M
ρ 

10. CORE CUTTER METHOD
o Measure the inside dimensions of the core
cutter.
o Determine empty weight of core cutter (
W1)
o Level the surface, about 300 mm square in
area. Place the dolly over the top of the
core cutter and press the core cutter into
the soil mass using the rammer.
o Stop the process of pressing when about 15
mm of the dolly protrudes above the soil
surface.
o Remove the soil surrounding the core cutter
and take out the core cutter.
o Remove the dolly. Trim the top and bottom
surface of the core cutter carefully using a
straight edge.
o Weight the core cutter filled with the soil
(W2). Remove the core of the soil from the
cutter. Determine the water content etc.

11. WATER DISPLACEMENT METHOD
 Suitable – Cohesive Soil only.
 Collect the Sample in Lumps and trim it to a Regular Shape.
 Weigh the Sample, W1.
 Coat the Sample with a thin layer of Paraffin Wax.
 Weigh the Coated Sample, W2.
 Take a Metal Container with Overflow Arrangement.
 Fill the Container with Water upto the Brim and Excess
Water is allowed to flow out through the Overflow
arrangement.
 Lower the Coated Sample into the Metal Container and
Collect the Water overflowing in a measuring jar.
 Measure the Vol. of Water Displaced, Vw.
 Vol. of Uncoated Specimen,





 

P
12
w
γ
WW
VV

12. CONT…
V
W
γ 1
t 
w1
γ
γ t
d

