SHEAR VANE

Question 1

what is the objective of shear vane?

Answer 1

• to measure the in situ undrained shear strength in clays.

- to measure indirectly the in-situ shear strength parameters of soils.

Question 2

explain vane shear procedure

Answer 2

1. The vane shear apparatus was cleaned and applied with grease to the lead screw for better movement handles.
2. The soil specimen in the container was taken which was generally 75mm in height and 37.5mm in diameter.
3. The soil surface was levelled on the top and the container on the base of vane shear test apparatus was amounted using screws.
4. The vane was lowered gradually into the soil specimen until the top of the vane was at a depth of 10 to 20mm below the top of the soil specimen.
5. The reading of the pointer on circular graduated scale which is the initial reading was noted down.
6. The vane inside the soil specimen was rotated using a torque applying handle at a rate of 0.1 degree per second.
7. When the specimen failed, the strain indicator pointer moved backwards on a circular graduated scale and the test stopped. The final reading of the pointer was taken down.
8. The procedure was repeated on two more soil specimens and the average shear strength value was calculated.
9. The diameter and height of vane was measured using Vernier Callipers.
10. The diameter and height of vane was measured using Vernier callipers.
11. Sensitivity of given soil sample was determined by repeating the above test procedure on remolded soil which was nothing but soil obtained after raped stirring of vane in the test above.
12. Sensitivity of soil = undisturbed shear strength/ remolded shear strength.

Question 3

How to analyze the data?

Answer 3

using a formula. T is torque, D is diameter or overall width of the vane, and H is height of the vane. The undisturbed and remolded strength obtained are useful to evaluate the sensitivity of soils.