How does the consolidation process affect the behavior of soft clay soils in civil engineering projects? Consider the various factors involved such as the initial void ratio, effective stress, and time$-$dependent settlement. Discuss the fundamental principles underlying consolidation theory, including Terzaghi's one$-$dimensional consolidation theory and its assumptions. Furthermore, explore the implications of consolidation on engineering design, particularly in the context of foundation engineering, where settlement control is crucial. Additionally, delve into advanced topics such as secondary consolidation and creep behavior, and their significance in long$-$term performance predictions of structures. Finally, analyze the challenges and limitations associated with consolidation theory and its application in real$-$world civil engineering projects, addressing issues like nonlinear soil behavior and complex loading conditions.