Step 1: Understanding the Concept:
Compaction is the mechanical process of densifying soil by reducing the volume of air in the voids.
Step 2: Detailed Explanation:
When soil is compacted:
1. Soil particles are packed closer together, increasing the dry density.
2. The interlocking between particles increases.
3. According to the Mohr-Coulomb equation \(\tau = c + \sigma \tan \phi\), densification generally increases the internal friction angle (\(\phi\)).
4. Consequently, the soil's resistance to deformation and sliding (shear strength) is enhanced.
Step 3: Final Answer:
Compaction leads to an increase in soil shear strength.