Page 19 - Geotechnical Engineering Soil and Foundation Principles and Practice

Introduction
14 Geotechnical Engineering

(Rammed Aggregate Piers TM ) in order to increase lateral stress and strength of the
surrounding soil.

1.19 GEOTEXTILES, GEOMEMBRANES, GEONETS

Another recent innovation in geotechnical engineering is the use of geosynthetic
materials for drains, filters, lagoon linings, or tensile reinforcement within soil.
Each use requires its own material properties, such as permeability (or imper-
meability), tensile strength, and toughness. Current uses of geosynthetics include
acting as a separator or filter under landfills or between different soil layers, and
as tensile members to improve foundation bearing capacity or stability of slopes
and retaining walls.

1.20 ON BEING A GEOTECHNICAL ENGINEER

As implied by the above discussions, geotechnical engineering involves a broad
knowledge base that includes soil mechanics and geology, and to a lesser degree
groundwater hydrology, soil science, mineralogy, and statistics. This complexity
precludes a ‘‘handbook approach’’ except at a technician level, and the M.S. or
M.E. normally is considered the entry-level degree for a geotechnical engineer.
One of the attractions of geotechnical engineering is that every new assignment is
essentially a research project that will require a written report, so the preferred
graduate degree is with thesis. Supporting course work includes courses in
geology, agronomic soil survey, engineering mechanics, statistics, soil physics, clay
mineralogy, and groundwater hydrology.

The demand for geotechnical engineers continues to increase as building expands
into difficult or marginal sites. In many areas an environmental as well as an
engineering assessment of a building site is required before building permits are
granted. Insurance policies normally do not cover damages from wars or ground
movements and leave it to owners and builders to try and avoid all wars and
ground movements.

Most geotechnical engineers are consulting engineers, and others are employed by
government agencies, highway departments, and universities. Doctorate degrees
are mandatory in academia, and are increasingly common at higher levels in
consulting.
Regardless of the level of academic training, the beginning consulting geotechnical
engineer often starts by performing mundane chores in the field, identifying and
describing soil samples as they come from borings. The next steps are to prescribe
and/or perform appropriate soil tests, interpret and summarize the test results,
and write reports under the direction of a senior engineer. All reports preferably

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