Transcript Document

Environmental Geomechanics: A Recent Development in
Geotechnical Engineering
DR. D. N. SINGH
PROFESSOR
Geotechnical Engineering Division
Department of Civil Engineering
I.I.T. BOMBAY
[email protected]
Civil Engineering
"...to design and construct public works..."
Transformation
Practice of improving and maintaining the
built and natural environment to enhance
the quality of life for present and the
generations to follow
Role of Civil Engineers
“Designers and Builders of
The Quality of Life…….”
Creators of the Civilised Society
Environment
Providing solutions to the needs of a developing global
population
Performers (on a world stage) as strategic thinkers and
global managers
Pillars of local Economies
Creating and maintaining complex infrastructure in
wealth creation
Subject Organization
Geotechnical Engineering
Geomechanics
Environment
Challenge
Rock Mechanics
Soil Mechanics
Foundations
Retaining Structures
Effect is more
pronounced
Seepage/Slopes/Dams
Environmental Geomechanics
Genesis
Population Explosion
Industrialization
Sluggish and “Don’t bother approach”
Ignorance
Human Greed
Is a Philosophy put in practice to deal with
under-ground “environment” & Problems associated with it
Combination/Blend of
Geotechnical Engg. and Environmental Engg.
Waste Disposal Strategies
Above ground storage
No protection
Protected by
geologic materials
Av e r a g e w a te r ta b l e
Shallow trench burial
Backfill
Engineered
geological materials.
B a c k fi l l
w e t p e rio d
a v e ra g e
d ry p e rio d
Deep Disposal
with backfill
retardation
material
Protected by
highgeologic
L a r g e b o r e h o l e s 1 0 to 2 0 m e te r s d e e p
Av e r a g e w a te r ta b l e
B a c k fi l l
U n fr c tu r e d
cla y e y
d e p o s i ts
B a c k fi l l
m a te r i a l
P r o te c ti v e G e o l o g i c
m a te r i a l
W a s te
W a s te
Issues are
• Ascertaining the quality of air, water, and land resources;
• Transport, use, and disposal of hazardous wastes
• water and wastewater treatment, and reuse.
• Analysis and design of foundation systems, seepage
control, earth dams and water resource structures,
response of foundations and embankments to
the ENVIRONMENTAL ACTIVITIES
Man made industrialization/population explosion
earthquakes/(& to some extent other natural calamities).
Natural
SCOPE of Environmental Geomechanics
Assessment of pollutants being discharged on/in the soil deposits
(Disposal/Handling/storage)
Process by which the pollutants travel in geo-environment
(Contaminant Transport)
Protection of ground water aquifers from contamination
(Containment)
Methods of cleaning the contaminated sites
(Remediation)
Methods of creating “Value added” products
(Recycling & Reuse)
Specific Studies on
• Hazardous wastes
• Physical, Chemical, Mineralogical, Electrical and
Thermal characterization
• Geoenvironmental hazards:
Natural and man made
Recycle and Reuse of Industrial waste(s)
• Role of Geotechnical engineering in environmental
protection
• Surface and subsurface contamination
• Characterization of contaminated ground
• Geoenvironmental site investigation
• Site assessment technologies
Soil-Water-Environment Interaction
The Natural
Environment
Geomicrobiosphere
The Particle Energy Field
Theory
Man Made
Environment
Environmental
Geotechnical
Problems
Requires knowledge from other Disciplines
Bacteriology
Biology
Climatology
Geohydrology
Geochemistry Hydrogeology
Microgeology
Physico-Chemistry
Soil Engineering Toxicology
Chemical Engg.
Geophysics
Mechanics
Soil Science
Understanding of Soil
response to
Environments
(Short & long-term)
The Natural Environment
Atmosphere
Biosphere
Oxygen Cycle
Nitrogen Cycle
Carbon Cycle
The Cycle of Nature
Hydrosphere
Lithosphere
Geomicrobiosphere
Ecosphere
Man-made Environment
Solid
Liquid
Agricultural wastes
Human and Animal wastes
Industrial wastes
Mine wastes……Acid mine waste
(due to oxidation of Iron Sulphide (FeS2) or Pyrites to H2SO4)
Nuclear wastes
Construction Effects (Blasting/Dewatering/debris…)
Soil Response to Environments
Soil structures (on/in/with)
Pore fluid characteristics
Soil-heat
Soil-Chemical
Soil Bacteria
Soil-Root
Soil-Electrical
Soil-Liquid (water)
Basic concepts of Analysis
Most geotechnical projects occur in nature
Long-term phenomenon
Soil is more sensitive and susceptible to environment
than any other construction material
Loading may greatly affect soil properties but not the only
Parameter to be considered
Think of other factors:
Heat
Moisture (wet/Dry)
Pollution intrusion
Classical Soil Mechanics: Some flaws
Specific gravity and Atterberg limits are constant
Void ratio and porosity as indicators of soil deformation
Water in the soil mass is mainly gravity water
(need to consider Environmental water)
Flow through a soil mass is only due to hydrostatic potential
(need to consider thermal/electrical/magnetic/chemical effects)
Constitutive models are arbitrarily chosen.
Stress-strain relationship
Soil Classification: Controlling Parameters
Present
scenario
(Parameters)
Proposed
scenario
(Parameters)
Grain-size distribution
Soil Consistency (moisture content)
LL
PL
PI
% Passing #200 Sieve
Specific surface
pH in pore fluid
Ion-exchange capacity
Absorption & adsorption
Thermal properties (Conductivity, diffusivity, specific heat)
Dielectric constant (Electrical properties)
Environmental Geomechanics Laboratory @ IIT Bombay
www.civil.iitb.ac.in/~dns
You are most welcome to Visit the laboratory