Soil-Structure Interaction Seminar - Foundation Performance ...

Geology
GENERAL SOILS AND GROUNDWATER
The Houston area is located on the Gulf of Mexico Coastal Plain, which is underlain largely by
unconsolidated clays, clay shales and poorly cemented sands to a depth of several miles. Nearly
all soil of the area consists of clay, associated with moderate amounts of sand. Some of the
formations in the Houston area consist of Beaumont, Lissie, and Bentley .
• The Beaumont formation has significant amounts of expansive clays, resulting in shrink/swell
potential. Desiccation of this formation also produces a network of fissures and slickensides in
the clay that is potential plains of weakness. The Beaumont formation generally occurs in South,
Southwest, East, and Central Houston. The Lissie and Bentley formations generally occur in
North and part of West Houston. These formations consist of generally sands and s-andy clays.
These soils 'are generally low to moderate in plasticity with low to moderate shrink/swell
potential.
General Soils Conditions
Variable soil conditions occur in the Houston area. These soils are different in texture,
plasticity, compressibility, and strength. It is very important that foundations for residential
structures be designed for subsoil conditions that exists at the specific lot in order to minimize
potential foundation and structural distress. Details of general subsoil conditions at various parts
of the Houston area are described below. These descriptions are very general. Significant
variations from these descriptions can occur. The General soil conditions are as follows:
Location
Northwest and Northeast Houston,
including Kingwood, The Woodlands,
Cypresswood, Copperfield, Atascocita
area, Fairfield, Worthom, and Oaks of
Devonshire
Soil Conditions
Generally sandy soils occur in these areas. The
sands are Houston, including generally loose
and underlain by relatively impermeable clays
and sandy clays. This condition promotes
perched water table formation which results in
the loss of bearing capacity the shallow
foundations such as a conventionally-reinforced
slab or post- tensioned slabs. This condition
also may cause subsequent foundation settlement
and distress.
GEOTECH ENGINEERING AND TESTING, INC. -------------·
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