311 GEOTECHNICAL ENGINEERING

1. FCE 311 GEOTECHNICAL ENGINEERING
2. INTRODUCTION TO SOIL MECHANICS
Department of Civil & Construction Engineering
University of Nairobi

2. 2.1 Definition of Soil
• Soil is the relatively loose mass of mineral
and organic materials and sediments
found above the bedrock, which can be
relatively easily broken down into its
constituent mineral or organic particles.

3. Soil Layers
• Soil consists of layers
of minerals
constituents of
variable thickness,
which differ from the
parent materials in
the morphological,
physical, chemical
and mineralogical
characteristics

4. 2.2 Soil Mechanics and
Geotechnical Engineering
Soil Mechanics
• Soil mechanics is a branch of engineering
mechanics that describes the behaviour of
soils. Soil mechanics provide the
theoretical basis for analysis in
geotechnical engineering

5. Geotechnical Engineering
• Branch of civil engineering concerned with
the engineering behaviour of earth
materials.
• Uses principles of soil mechanics, rock
mechanics and engineering geology to
investigate:
1.Subsurface conditions and materials,
2.Relevant physical/mechanical and
chemical properties of the materials,

6. Geotechnical Engineering – cont’d
3. Evaluate stability of natural slopes and
man-made soil deposits,
4. Access risks posed by site conditions,
5. Design earthworks and structure
foundations and
6. Monitor site conditions, earthwork and
foundation construction.

7. Typical geotechnical engineering project
• A typical geotechnical engineering project
begins with a review of project needs to
define the required material properties.
• Then follows a site investigation of soil,
rock, fault distribution and bedrock
properties on and below an area of interest
to determine their engineering properties.

8. Typical geotechnical engineering project
• A geotechnical engineer then determines
and designs the type of foundations,
earthworks and pavement subgrades
required for the intended man-made
structures to be built.
• Foundations are designed and constructed
for structures of various sizes such as
high-rise buildings, bridges, medium to
large commercial buildings, and smaller
structures where the soil conditions do not
allow code-based design.