task : $630$##@@

"What is the foundational theory behind civil engineering, and how does it inform the principles and practices within the field? Explore key theories such as structural mechanics, fluid mechanics, soil mechanics, and materials science, elucidating their roles in designing, constructing, and maintaining infrastructure. Discuss the significance of theories like elasticity, plasticity, and failure theories in analyzing structural behavior and ensuring safety in civil engineering projects. Furthermore, delve into the application of theories such as hydraulics and hydrology in managing water resources and mitigating environmental impacts. Ultimately, elucidate how theory serves as the backbone of civil engineering, shaping its advancements and innovations."