Soil investigation is the process of examining the physical and chemical properties of soil at a specific site. This is essential for construction projects, as it helps engineers understand the soil's strength, stability, and drainage capabilities. By collecting soil samples and conducting tests, professionals can determine if the ground can support structures like buildings and bridges. The investigation typically involves drilling boreholes, taking soil samples, and performing laboratory tests. These tests assess factors such as soil composition, moisture content, and bearing capacity. The results guide design decisions and ensure safety and durability in construction projects.