Soil Bearing Capacity I

CE 240 Soil Mechanics & Foundations Lecture 15.1

Soil Bearing Capacity for shallow foundations I (Das, Ch. 15)

Class Outline • • •

Introduction Ultimate bearing capacity for shallow foundations Ultimate bearing capacity: Terzaghi’s equation

The lowest part of the structure is called foundation. Properly designed foundations can transferring the load of the structure to the soil without overstressing. So we have to evaluate the bearing capacity of soils.

Shallow foundations: (a) Spread footing; (b) mat foundation.

Deep foundations: (for heavier structures) (c) Pile foundation; (d) Drilled shaft.

Figure 15.1

Settlement - compressibility - elastic/plastic - Ch. 10. Shear failure – use Coulomb criterion – this chapter.

Figure 15.2

Figure 15.3a: General shear failure

Figure 15.3b: Local shear failure

Rankine passive zone

elastic

Radial shear zone

For local shear failure

For loose to mediate dense soil

Reading Assignment: Das, Ch. 15