Shallow groundwater reduces soil shear strength by decreasing apparent cohesion and increasing pore water pressures, which reduces effective stress and shear strength. Bearing capacity can be estimated from field tests like standard penetration tests, cone penetration tests, and plate load tests. The standard penetration test blow count needs to be corrected based on the energy ratio of the hammer to account for different hammer efficiencies.

1. 1
Bearing Capacity Theory
Bearing Capacity

2. 2
Groundwater Effects
Shallow groundwater affects shear strength in two ways:
 Reduces apparent cohesion that takes place when soils
are not saturated; may necessitate reducing the
cohesion measured in the laboratory
 Pore water pressure increases; reduces both effective
stress and shear strength in the soil (same problem as
is experienced with unsupported slopes)

3. 3
Groundwater Effects

4. 4
Bearing Capacity from Field Tests

5. 5
Bearing Capacity from SPT

6. 6
Bearing Capacity from SPT

7. 7
Bearing Capacity from SPT

8. 8
Bearing Capacity using CPT

9. 9
Bearing Capacity for Field
Load Tests PLT

10. 10
Bearing Capacity for Field Load Tests PLT
 For Granular Soils:
 For Cohesive Soils:

11. 11
Correction of Standard penetration number
 It has been suggested that the SPT be standardized to some
energy ratio Er which should be computed as
 Note that larger values of Er decrease the blow count N nearly
linearly, that is, Er45 gives N = 20 and Er90 gives N = 10;
 Example of N for Er45 = 20 we obtain for the arbitrarily chosen
Er = 70, (Er70):
N for Er70 = 13