What is the purpose of the Vane Test?

The Vane Test is a specialized field test used primarily to determine the shear strength of saturated cohesive soils, particularly clay. This test is particularly useful because it provides a direct measurement of the undrained shear strength, which is critical for understanding the behavior of clay soils under loading conditions, especially in geotechnical engineering applications such as foundation design and slope stability analysis.

During the test, a vane consisting of a cylindrical shaft with horizontal blades is inserted into the soil, and the torque required to rotate the vane is measured. This torque is related to the soil's shear strength, allowing engineers to evaluate stability and failure potential in saturated conditions. The simplicity and effectiveness of this test in cohesive soils make it a standard practice in geotechnical investigations, particularly in assessing the in-situ conditions before construction.

Other possible options pertain to different soil properties, such as hydraulic conductivity, drainage capabilities, and soil texture, but these do not align with the Vane Test's primary function, which focuses specifically on shear strength assessment. Thus, the correct purpose of the Vane Test is indeed to determine the shear strength of saturated cohesive soils.