What are the key principles behind the design and implementation of deep foundation systems in civil engineering? Discuss the various types of deep foundations, such as piles and drilled shafts, and explain the factors that influence their selection, including soil conditions, structural loads, and site constraints. Furthermore, analyze the methods used for designing deep foundations, including load estimation, settlement analysis, and construction considerations. Lastly, explore the challenges and advancements in deep foundation design, such as the incorporation of innovative materials and techniques, and discuss their implications for the future of civil engineering projects.