Triaxial Shear Test.pptx as per is codei in ge

triaxial test

1. Triaxial Shear Test

2. Triaxial Shear Test

3. Ws = wt of solids

4. Cell Pressure or Confining Pr = Skemptons PP Coefficient if β = 1, i.e soil is 100% saturated PP = pore water pr , if effective stress taken, consider PP UU Test Height of sample = 140 mm Dia of sample = 70 mm

5. (BP) Back Pressure = i.e direct induction of water into the soil pr BP < PP BP is opposing pr to PP Increase PP 5 to 10 and then calculate β = (10/20)x100=50% Then increase cell pressure to 40 kPa and find saturation and continue up to 100% saturation on trial and error basis Back Pressure BP is opposing pr to PP

6. σ 3= 17X10 =170 KPa

7. Apply a stress , to shear the soil sample using a strain controlled condition similar to UCS test. Adjust the shear rate depending on the soil type. Here, adjust it to 0.5 mm/min This additional stress is called deviator stress

8. How to terminate the test Criteria 1: When the strain reaches up to 20%, stop the test. Height of the sample is 140 mm, shear rate is 0.5mm/min, then the displacement in the sample is 28 mm as shown in the below fig and stop the test. Let us say Criteria 2: If you draw a plot Strain Vs Stress, if the stress is decreasing (after the peak) before the 20% strain criteria, then stop the test

9. Table Soil changes its dimensions, hence calculate corrected area

10. Trial 1: σ 3 = 170 Kpa Let us say Max σ 1 = 330 K Pa In the trial2 double the σ 3 = 170 Kpa Let us say Max σ 1 = 700 K Pa , Draw the Mohr Circles