For analysis and design of foundation structures, two important soil parameters, compressibility and the stress-strain behavior of soil, must be examined. The compressibility or volume changes include shrinkage, swelling, compaction (densification), and consolidation (settlement). The stressstrain-time characteristics of soil include strength, failure criteria, and creep. Shrinkage and swelling have been discussed in Sections 6.2 and 6.3. The other parameters are discussed in this chapter.