Chapter 8: Settlement of Shallow Foundations

What types of settlement does a shallow foundation undergo?

Immediate (elastic), primary consolidation, and secondary consolidation settlement

How is elastic settlement estimated for a foundation on saturated clay?

Using elasticity equations based on soil stiffness and applied load

How is foundation settlement analyzed using elasticity theory?

Assumes soil behaves elastically; settlement depends on stress increase and modulus of elasticity

What is an improved method for elastic settlement calculation?

Uses correction factors (shape, depth, rigidity) to refine basic elasticity solutions

What is the strain influence factor in settlement analysis?

A factor used to estimate elastic settlement in sands by accounting for strain distribution with depth

How are SPT N-values used to estimate settlement in sand?

Empirical correlations relate N-values to soil stiffness and settlement

How is settlement evaluated using pressuremeter test results?

Uses in-situ stiffness measurements to estimate deformation under load

How is settlement estimated using a load-settlement curve?

Based on field or lab data showing how soil deforms under increasing load

How is consolidation settlement analyzed?

Based on change in effective stress and compressibility parameters (Cc, Cs)

What is the three-dimensional effect in consolidation settlement?

Settlement is influenced by foundation shape and size, not just 1D compression

How is secondary consolidation settlement estimated?

Based on time-dependent creep after primary consolidation using secondary compression index

What is a field load test for a shallow foundation?

Test where load is applied to a plate/footing to measure actual settlement behavior

How are bearing capacity values determined in standard codes?

Based on empirical data, safety factors, and experience from past projects

What is tolerable settlement?

The maximum settlement a structure can undergo without damage or serviceability issues

What soil improvement techniques reduce settlement?

Compaction, preloading, vertical drains, grouting; increase strength and reduce compressibility