The direct shear test is used to measure which property?

The direct shear test is used to measure which property?

• A. Measure density
• B. Measure the shear strength properties of soil or rock material, or of discontinuities in soil or rock masses.
• C. Measure permeability
• D. Measure thermal conductivity

Answer: (B)

The direct shear test evaluates how much shear resistance a soil, rock material, or a planar discontinuity can provide along a defined sliding plane. In the test, a normal load is applied while a shear load is gradually increased until the plane fails, giving the shear strength at that normal stress. By doing tests at several normal stresses, you can determine the parameters that describe shear strength, typically cohesion and the internal friction angle, through the Mohr-Coulomb relationship. This focus on resistance to sliding on a plane is why the test is used to characterize shear strength properties, rather than density, permeability, or thermal conductivity, which require different tests.

The direct shear test evaluates how much shear resistance a soil, rock material, or a planar discontinuity can provide along a defined sliding plane. In the test, a normal load is applied while a shear load is gradually increased until the plane fails, giving the shear strength at that normal stress. By doing tests at several normal stresses, you can determine the parameters that describe shear strength, typically cohesion and the internal friction angle, through the Mohr-Coulomb relationship. This focus on resistance to sliding on a plane is why the test is used to characterize shear strength properties, rather than density, permeability, or thermal conductivity, which require different tests.