Direktscherprüfungen

Direktscherprüfungen, also known as direct shear tests, are a fundamental laboratory or field method used in geotechnical engineering to determine the shear strength of soil. This strength is crucial for analyzing the stability of foundations, slopes, and other earth structures. The test involves placing a soil sample within a metal or plastic shear box, which is typically split into two halves. Water is usually applied to saturate the sample, and a normal stress is applied perpendicular to the plane of the shear. The shear box is then subjected to a horizontal shearing force at a controlled rate, while the horizontal displacement and the corresponding shear force are measured. The shear strength is typically calculated at different normal stresses to establish a Mohr-Coulomb failure envelope, from which the cohesion and angle of internal friction of the soil can be determined. Direktscherprüfungen can be performed under drained or undrained conditions, influencing the pore water pressure response and the effective stress parameters obtained. They are relatively simple to perform and are widely used for various soil types, though they have limitations in representing complex stress conditions found in situ.