greg o'rourke - engenium - integrating engineering geology into corridor earthworks to improve...
DESCRIPTION
Greg O'Rourke delivered the presentation at the 2014 Heavy Haul Rail Conference. The 2014 Heavy Haul Rail Conference had a focus on driving efficiency with smarter technology. Australasia’s only heavy haul rail event is the annual meeting place for professionals interested in the latest projects, technologies and innovation in this dynamic sector. For more information about the event, please visit: http://bit.ly/hhroz14TRANSCRIPT
Integrating Engineering Geology Into Corridor Earthworks to Improve Efficiency & Productivity
Greg O’Rourke, Executive Director - Rail
This presentation has been produced in
cooperation with 4DGeotechnics
This presentation will:
Explain how using engineering geological techniques will add value to any corridor project
Provide examples of lost value opportunities
Explain why “hard information” often comes too late to impact positively on a project
Introduction
Engineering geology is the application of the
geologic sciences to engineering practice for the purpose of assuring that the geological factors affecting the location, design, construction, operation and maintenance of engineering works are recognised and adequately provided for.
What is Engineering Geology?
The below track component of the railway
(earthworks) normally represents the most variable
component of the fixed infrastructure.
It is normally built out of natural materials on and in
a natural geological setting.
Because it is variable it often presents the most
engineering risk.
Understanding the geology therefore allows us to
predict likely issues and therefore manage this risk
from an early stage of the project.
Why is this important?
Conditions of a site are the product of the
history of the site.
Therefore understanding the geology allows
early anticipation of site ground conditions and likely engineering performance.
Total Geology Concepts
Typical Land Surface
Anticipation of ground conditions leading
to:
– informed corridor selection
– Locking in value
– Less surprises
– Targeted geotechnical investigation
– Collected data on a corridor, not an alignment.
What are the benefits of adopting this approach early?
Geological Knowledge
Framework
100%
50%
Desk Study Mapping Ground
Breaking
Investigations
Supplementary
Ground
Breaking
Investigations
Construction
Dependent
on Approvals
Biggest
decisions on
alignment are
made before
ground
disturbance
Alternative Often Typical Approach…
Designated by the Blue Line
100%
50%
Desk Study Mapping Ground
Breaking
Investigations
Supplementary
Ground
Breaking
Investigations
Construction
Biggest
decisions –
little
information
Main
information
gathering
commences
here A lot of
information
gathering
occurs here
– Surprises!
Recommended approach is:
Introduce engineering geological principals
early
Initially use available information for initial
route selection
Then site inspection followed by detailed
mapping
Total Geology Approach (Typical)
Total Geology Approach (Typical)
Identification of geohazards
Route optimisation and identification of construction materials
Corridor can be selected
Subsurface investigation
Total Geology Approach (Typical)
Develop reference conditions
Apply the observational method
Total geology approach (continued)
An Example
Looking for the
line of least
resistance
The same alignment using published data
Same alignment with aerial photography
Same alignment with geological mapping
Cut through Rock
requires drill and
blast
Likely poor
foundation
conditions
Potential borrow
areas
Potential borrow
areas
Use this information to reduce risk and cost
Alignment moved to
avoid poor
foundations, reduce
drill and blast and take
advantage of an
abundance of good
borrow materials
Using Traditional method
Select alignment based on topography
When able to, approvals allowing, test pit or drill
Depending on where targets are chosen, may discover unfavourable conditions’
No real knowledge on where to move it.
Findings
Lang Hancock Railway
Train
Loadout
Bridge
Site
Lang Hancock Railway
Bridge
replaced with
culverts at
design stage
Void below
surface
discovered
during
construction
Once hard investigatory information is available corridor is
already locked in.
If problems are only discovered when drilling and testpitting
occurs, often too late to do much about it.
Any changes are likely to require further investigation –
expensive and time consuming – or gaps in information are
presented to contractors, leading to potential latent
conditions claims.
Generally more expensive than a total geology approach
without really managing risk properly.
Problems arising from not taking a total geology approach
Adopting total geology approach:
Provides the right information at the right time
Enables informed decision making (eg corridor selection)
Enables risk management to occur, including anticipation of
geohazards and the like.
Provides information to enabling a cost effective site
investigation to take place
Allows changes to be anticipated and modifications to be
made with minimal disruption
Engineers and geologists working together to ensure
beneficial outcomes for all.
Conclusions
John Kennedy and Ian Lewis from 4DG
Acknowledgements