Soil Exploration - Soil Properties: Testing, Measurement, and Evaluation - page 13

later in this chapter. Twenty-two additional field and laboratory tests
are covered in subsequent chapters.

The term groundwater table (or just water table ) has been mentioned
several times earlier in this chapter. This section presents more detailed
information about this important phenomenon as it relates to the study
of soils.
The location of the water table is a matter of importance to engi-
neers, particularly when it is near the ground surface. For example, a
soil's bearing capacity can be reduced when the water table is at or near
a footing. The location of the water table is not fixed at a particular site;
it tends to rise and fall during periods of wet and dry weather, respec-
tively. Fluctuations of the water table may result in reduction of founda-
tion stability; in extreme cases, structures may float out of the ground.
Accordingly, foundation design and/or methods of construction may be
affected by the location of the water table. Knowing the position of the
water table is also very important when sites are being chosen for haz-
ardous waste and sanitary landfills, to avoid contaminating groundwater.

GROUNDWATER
TABLE

Table 2-1 Common Types of Testing

ASTM
Designation

AASHTO
Designation Property of Soil Type of Test

(a) Laboratory testing of soils

Grain-size distribution Mechanical analysis D422 T88

Consistency Liquid limit (LL) D4318 T89

Plastic limit (PL) D4318 T90

Plasticity index (PI) D4318 T90

Unit weight Specific gravity D854 T100

Moisture Natural water content

Conventional oven method

D2216 T93

Microwave oven method D4643

Shear strength Unconfined compression D2166 T208

Direct shear D3080 T236

Triaxial D2850 T234

Volume change Shrinkage factors D427 T92

Compressibility Consolidation D2435 T216

Permeability Permeability D2434 T215

Compaction characteristics Standard Proctor D698 T99

Modified Proctor D1557 T180

California bearing ratio (CBR) D1883 T193

(b) Field testing of soils

Compaction control Moisture-density relations D698 T99, T180

In-place density (Sand-cone Method) D1556 T191

In-place density (Nuclear Method) D2922 T205

Shear strength (soft clay) Vane test D2573 T223

Relative density (granular soil) Standard Penetration test D1586 T206

Soil type Cone penetration test D3441

D5778

Permeability Pumping test

Bearing capacity
Pavement CBR D1883 T193

Piles (vertical load) Pile load test D1143 T222