To determine Unconfined Compressive Strength and Shear Strength of the given soil sample.
Unconfined Compression Testing Apparatus, Sample Extruder, Dial Gauge, Split Mould, Load Frame. etc..
Unconfined Compression Strength (UCS) is the maximum axial compressive stress that the sample can withstand under Unconfined Conditions.
Measure the Diameter and Height of the Split Mould.
Diameter of the Split Mould, d (cm) = _________
Height of the Split Mould, h (cm) = _________
Calculate the Volume of dry soil and amount of water required for the preparation of soil sample.
Variables Used in Calculations
Height of the Split Mould, h (cm) = 7.60cm
Diameter of the Split Mould, d (cm)= 3.80cm
Dry Density of Soil (δ) = 2.642g/cc
Water Content = 18%
(π × d2/4) x h
Volume of the mould, V (cm3) =
(V) X (δ)
Mass of soil required, M (g) =
Mass of the Soil Required X Water Content
Volume of the water required, m (ml) =
Add dry soil into a bowl and mix with water throughly using Straightedge.
Fix the bottom collar and oil the split mould. Fill the prepared soil sample into it and fix the top collar.
Place the mould in the Load Frame and compact the sample by applying the Compressive Load.
Note :- Load frame is used to compact the soil sample that is present in the mould.
Eject the specimen from the mould and check the Height and Diameter of the specimen.
Diameter of the Split Mould, d (cm) =_________
Height of the Split Mould, h (cm) = _________
Fix the Proving Ring to the Loading Frame and place the hardened steel ball on the Bearing Plate.
Place the specimen on the base plate of the Loading Frame and adjust the centerline of the specimen such that the Proving Ring and the steel ball are in the same line.
Fix the strain Dial Gauge over the lower plate. Bring down the upper plate to touch the upper surface of the specimen.
Adjust the gear position on the Load Frame to give suitable Vertical Displacement.
Apply the load to the specimen and record the readings of the Proving Ring Dial and Compression Dial continue the loading till the failure is completed.
Proving Ring Reading
Compression Dial
| Proving Ring Reading,PRR (div) | Deformation,l (mm) | Load (kg) |
Variables
Length, L (mm) = 76mm
Area, A (cm2) = 11.34cm2
| Proving Ring Reading,PRR (div) | |
| Deformation, l (mm) | |
| Load (kg) | |
| Strain, e |
e = l⁄L
|
| Corrected Area, Ac (cm2) |
I= π × d4⁄64
Ac = (A)⁄( 1 - e)
|
| Stress, ꞇ (kg/cm2) |
Stress =Load⁄Area
|
| Proving Ring Reading,PRR (div) | Deformation, l (mm) | Load (kg) | Strain, e | Corrected Area, Ac (cm2) | Stress,ꞇ (kg/cm2) |
Lenth (L) = 76mm
Area (A) = 11.34cm2
| Unconfined Compressive Stress, σ (kg/cm2) | 1.59 | Shear Stress, ꞇ (kg/cm2) |
Shear Stress = σ⁄2
|
| Angle of Shear Resistance, Ѳ (°) | 42 |
| Cohesion of Soil, c (kg/cm2) |
σ = 2 × c × tan (45+(Ѳ/2))
|
Graph
Horizontal Angle α
Vertical Angle,Ø
Cohesion, C (kg/cm2)
Result
The Value of cohesion obtained for analytical method =_________
The Value of cohesion obtained for graphical method =_________
Angle of interal friction, Ø =_________
The Unconfined Compressive Strength of the given soil =_________
Shear stress =_________
Inference
The Unconfined Compressive Strength of the given soil is. and the Shear stress is
