1. Triaxial Compression Test ASTM D-2166 /02
Experiment # 9
Triaxial Compression Test
ASTM D-2166 /02
Soil Mechanics Lab CE 350

2. Content Objective Definitions Required Apparatus Data and calculations
Determination of Shear Strength Parameters
Applications
Soil Mechanics Lab CE 350

3. Objective
To determine both the un-drained and drained shear strength parameters of soils .
Soil Mechanics Lab CE 350

4. Definitions
The triaxial compression test is a procedure that permits different horizontal and vertical stresses to be applied to the soil specimen simultaneously and thus closely duplicate the expected field
Soil Mechanics Lab CE 350

5. Types of triaxial Test Unconsolidated – un-drained (UU)
Consolidated – un-drained (CU)
Consolidated – drained (CD)
Soil Mechanics Lab CE 350

6. Types of triaxial Test Case # Applied Cell Pressure
Applied Deviator Pressure
Test Type 1
Valve Open
C-D 2
Valve Closed
C-U 3
U-U
Soil Mechanics Lab CE 350

7. REQUIRED APPARATUS Triaxial compression device.
Triaxial cell (including loading piston and pedestal).
Rubber membrane.
Membrane stretcher.
O-rings.
Porous stones.
Compressed
air source.
Vacuum and
air pressure supply.
Specimen trimmer (for cohesive soil)
Soil Mechanics Lab CE 350

8. REQUIRED MEASUREMENTS
Diameter of specimen, D.
Height of specimen, L.
Initial moisture content.
Final moisture content.
Proving ring reading.
Vertical deformation gage reading.
Soil Mechanics Lab CE 350

9. SAMPLE PREPARATION Undisturbed Sample Remolded Sample
Soil Mechanics Lab CE 350

10. Aspect Ratio 2 < H/D < 3 H/D < 3 To prevent buckling action
H/D > 2 To prevent fraction between load plate and surface of specimen
Soil Mechanics Lab CE 350

11. Deformation. dial reading
DATA AND CALCULATIONS
Deformation. dial reading
(div.)
Deformation dh (mm)
Load ring reading
Strain
(dh/h)
Corrected area
Axial force (P)
(N)
Axial stress qu (N/cm2) R1
R1*C1 R2
dh/h
R2*C2
Ac = Ao/(1-Δh/Lo)
qu = P/Ac
Soil Mechanics Lab CE 350

12. PRESENTATION OF RESULTSqu
Peak
Constant
Shape For Stress Curve According to Type of Soil
Deviator Stress for Different Cell Stress
Soil Mechanics Lab CE 350

13. Mohr’s Circle For C.D Tests3 s3 qu s1
U = 0
s1 = s’1
s3 = s’3
Soil Mechanics Lab CE 350

14. Mohr’s Circle For C.U Tests3 s3 c s t s1
U > 0
s’1 = s1 - u
s’3 = s3 - u s' st s' st s
Soil Mechanics Lab CE 350

15. Mohr’s Circle For U.U Tests3 s3 qu s1
U > 0
s’1 = s1 - u
s’3 = s3 - u
Soil Mechanics Lab CE 350

16. Applications Prediction of soil behavior
Estimation of bearing capacity
Estimation of bearing capacity of pils
Estimation of lateral earth pressure
Soil Mechanics Lab CE 350