Q1: For shear strength, triaxial shear test is suitable because

ANS:E - all the above.

The correct statement from the options provided is: "all the above." Each of the provided points explains a reason why the triaxial shear test is suitable for shear strength analysis:

1. It can be performed under all three drainage conditions: Triaxial shear tests can be conducted under different drainage conditions: drained, undrained, and partially drained. This versatility allows engineers to assess the soil's behavior under various real-world conditions.
2. Precise measurement of the pore pressure and volume change during the test is possible: Triaxial shear tests enable the measurement of pore water pressure and volume change during the test, providing valuable insights into the soil's behavior under different loading conditions.
3. Stress distribution on the failure plane is uniform: Triaxial shear tests help in achieving a relatively uniform stress distribution on the failure plane, which is crucial for accurately determining the soil's shear strength parameters.
4. State of stress within the specimen during any stage of the test as well as at failure is completely determined: Triaxial shear tests allow engineers to control and monitor the stress state within the soil specimen throughout the test. This helps in understanding the soil's response to stress and determining its shear strength characteristics accurately.