Engineering Geology
Earth Hazazrds
Infastructure
Waste
Earthquakes
Volcanic Eruptions
Tsunamis
Landslides
Hazards
Building collapse
Ground Liquefaction
Fires
Landslides
soil substantially loses strength and stiffness
Due to an applied stress such as shaking during an earthquake
Concentrated on plate boundaries
Generated by submarine (below sea) Earthquakes
Initiated by Earthquakes
Initiated by Volcanic eruptions
Initiated by Slope failure
Generated by volcanic island collapse
Generated by meteorite impacts into the sea
Generated by landslides into the sea
Hazards
Lava flows
ash fall
Pyroclastic flow
Lahars
Risk reduction methods
Minimum standards for reinforced concrete
Safety glass to replace conventional glass in skyscrapers
Retrofitting foundations with rubber dampeners
Smart values to turn off oil/gas supplies when Earthqukes occur
Use of bolts to pin walls to floors
Reduce chance of 'pancaking'
collapse occurs from the top-down
Upper floors collapse down onto lower ones, causing collapse
Fasteing of major appliances to walls to prevent movement
E.g. fridges, TVs
Deep foundations into solid bedrock
New building's with lower center of gravity
Not affected by liquefaction
Avoid building on areas prone to liquefaction during Earthquakes
Computer-controlled weights on the top of skyscrapers to counter any swaying caused by a seismic event
Floors able to slide horizontally on muli-storey buildings
Through the use of a rack and pinion device and teflon (non-stick) coated materials on the base/top of floors
Avoid building on:
Reclaimed land
marshes
Old lake beds
River floodplains
Reinforce weak points in infrastructure to ensure they are Earthquake resistant
Tunnels
Bridges
Flyovers
Freeways/Motorways
Risk reduction methods
Implementing building restrictions in areas prone to eruptions
Risk reduction methods
Buildings on stilts in areas prone to tsunamis
Allow water to flow underneath
Planting of mangroves in coastal areas prone to tsunami
Mangroves absorb the force of the waves
Prediction of Hazards
Measuring Ground deformation
using tiltmeters
Measure minute changes the angle of the Earth's surface
ground increasing in tilt/bulging over time
Magma moving towards surface
land fails
- major Earthquake
- volcanic eruption
Prediction of Hazards
Groundwater changes
Monitor in Boreholes:
Water chemistry
Water levels
Temperatures
Increased Temp.'s , increased dissolved sulphur dioxide, increased carbon dioxide
Falling water levels, increase in dissolved radon gas
Sometimes occur before major seismic event
Magma moving towards surface
May lead to volcanic eruption
Gas emissions
Correlation spectrometers (COSPEC) around active volcanoes
rapid carbon dioxide and Sulphur dioxide emission increase just (24-48hr) before eruptions
Hazard Interval Patterns (Seismic Gaps)
Seismic Gaps in time
Long time since Earthquake at a certain part of the Boundary (compared with other segments along the same boundary/structure)
Seismic gap in space
Long time since Earthquake around/near to a certain part/segment of the Boundary (compared with other segments along the same boundary/structure)
(At Segments of an active fault known to produce significant earthquakes)
Detailed record of past seismic events
With dates
Can be used to calculate an average resurgence interval for a seismic event over a certain magnitude
With locations
Areas that haven't expericnced seismic events for a long time/at all are more likely to have the next seismic event
Seismic event more likely
Risk reduction methods
Investment in emergency services and rescue equipment
Bulldozers, JCBs, cranes, fire engines
Doctors, paramedics, hospitals
heat-seeking equipment, sniffer dogs
Factors affecting level of risk (to hazards)
Population density
Increased pop. density = increased casualties
Technology
Aseismic desgn
Early warning systems
Rapid response emergency services
Land use planning
High risk areas
Parks, Golf couses, ect.
Low risk areas
Hospitals, schools, ect.
Intermediate risk areas
Houses, commerical
Communication
lack of PCs, broadband, political will
Warnings poorly communicated
Increased casualties
Decreased casualties
In MEDC's and HEDC's
In LEDC's
(Least/Less Economically Developed Countries)
Causalities higher (per pop.) in LEDC's
as they lack money to invest on Disaster prevention
More pressing matters occupy resources (e.g. shelter, education, health care)
Warning + Evacuation schemes
Earthquake drills
Clear Evacuation routes
Early warning
Decreased casualties
Factors that affect waste disposal
Waste type
Domestic
Hazardous
Medical waste, industrial waste, radioactive waste
Household waste, garden waste, ect.
Waste that needs special disposal
Permability
Impermeable rock types
Permeable rock types
Site must be made impermeable through Engineering
Clay linings
Artificial geomembranes
(Type of textile sheet to prevent seepage from waste disposal site)
preventing contamination
Toxic Leachate is collected in a sump and removed from landfill for treatment
Leechate
r the liquid pollution that seeps through a landfill's waste pile when it rains or snows
(landfill)
monitor local rivers, ponds, wells and springs
ensure that water quality is
of an acceptable and safe standard
Ensure not contaminated
Toxic waste storage
in sealed drums
underground in impermeable rocks
(e.g. as in disused salt mines)
at the surface in secure repositories
Restoring contaminated ground
removing the soil and replacing it with a cleaner alternative
Employing bioremediation using microbes
and/or plants to extract the toxic materials from the ground
Remove/harvest
treat so that they are safe
bioremediation
process that uses mainly microorganisms, plants, or microbial or plant enzymes to detoxify contaminants in the soil and other environments
Geological factors affect the siting of engineering projects
Such as:
Dams
Reservoirs
Cuttings
Tunnels
Rock fact cut out for road, rail, ect.
Stability of the rock
Mechanically strong
Mechanically weak
Can support steep slopes
Unable to support steep slopes
collapse/slump after periods of high rainfall
e.g. clay, mudstone, shale
e.g. limestone, sandstone, granite
Permeability of the rock
Permeable
Absorbs water
Increases in mass
increases pore water pressure
the pressure experienced by water trapped in pores
slope failure
Presence of faults + joints
Faults and joins common
Fault reactivaton may occur
Fault may reopen due to stress, think 'structures' unit
Expensive engineering solutions to re-stabilize area
Dip (direction + angle) of strata
Strata dips down towards excavation
Expensive slope stabilization
Strata dips down away from excavation
Naturally stable
Methods to overcome geological factors/problems
Rock bolts
shockcrete
Gabion baskets
Slope re-profiling
Drainage
Or slope failure
slope failure
(slope collapse)