"How does soil type affect the stability of structures? Discuss the role of soil mechanics in civil engineering projects, considering factors such as compaction, shear strength, and settlement. Explain the significance of conducting soil tests and analysis prior to construction. Provide examples of how different soil types $($e$.$g$.,$ clay, sand, gravel$)$ influence foundation design and construction methods. Highlight the importance of proper drainage systems in mitigating soil$-$related risks and ensuring long$-$term structural integrity."