The triaxial test is a laboratory procedure used to determine the mechanical properties of soil. It involves placing a cylindrical soil sample in a chamber where it is subjected to controlled pressure from all sides, simulating conditions found underground. The test measures how the soil behaves under different stress levels, providing valuable data on its strength and stability. During the test, the soil sample is also subjected to axial loading, which helps assess its shear strength. The results are crucial for engineers and geologists when designing foundations, slopes, and other structures, ensuring safety and reliability in construction projects.