Today I would like to tell you more information about my project which I am currently working on.
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| Embankment |
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| Cutting |
In Ireland and the UK, much of their infrastructure networks, like cuttings and embankments, were constructed many centuries ago prior to modern engineering standards. Earthworks were commonly constructed using local materials, which may not have
been the best choice in terms of engineering parameters but were, of course,
economically convenient at that time. Consequently, many of these assets are at
risk of failure.
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| Example of cutting failure |
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| Example of embankment failure |
Continuous
maintenance of the existing slopes along transportation networks is essential.
However, it can be very costly for infrastructure owners. For example, it has
been estimated that the cost of maintenance for embankments alone in the UK for
the year 1998/99 was around £50 million. However, the cost
of emergency repairs, in case of failure, is approximately ten times greater
than the cost of planned maintenance works. Consequently, the ability to
accurately assess the risk for earthworks along transport infrastructure
networks is imperative.
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| risk for the users caused by a failure |
Last
but not least, sudden failures involving transport infrastructure can be
extremely dangerous for the users. The factor of safety is used to
describe the stability of a slope. There are many definitions of the factor of
safety but in general terms they all involve the shear strength of the soil and
the shear stress that is required for equilibrium. This ratio must be major
than the unit value in order to guarantee the safety of the slope.
Nowadays,
stability of slopes is an increasingly common problem, due to the recent
extreme climate changes. Weather forecasts show that both monthly minimum and
maximum temperature are constantly increasing and, in terms of rainfalls, we
expect rainfalls of shorter duration but more intense, more violent. This may
lead to fast changes in the physical parameters in the terrain, such as water
content, infiltration capacity, soil permeability, suction etc., can produce
sudden and dangerous failures. In particular, the most recent studies agree
about the thesis that failure would be caused by the loss of contribution of
the matric suction or, which is the same, in pore pressure.
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| Pore water pressure for present and future climate scenarios |
This graph shows
how in the future climate we expect a general decrease of contribution of the
matric suction, and in particular in correspondence of the autumn/winter
seasons, which will expose at even higher risks slopes.
Irish Rail commissioned Gavin & Doherty
Geosolutions to develop a risk model and decision support tool for Irish Rail cutting and embankment assets. The aim of the tool is to
determine the relative risk for each of the cutting/embankment assets across the network. Using
these values, assets can be ranked, thus enabling the identification of the
most critical earthworks before the failure (slope instability/landslide)
occurs. This will aid management decisions in prioritization of maintenance and
remediation budgets. Additional functionalities of the tool include scenario
analysis and cost-benefit analysis (CBA) that rely on the original risk model.
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| C&D Decision Support Tool |
Hence, the objective is to continue towards this direction, developing more advanced methods to evaluate the safety of earthworks (cuttings & embankments) along transport networks. The achievement is to create a model which will function as an advanced warning system, providing support to transport infrastructure managers who are faced with an increasing number of failures associated with climate change effects. Overall, the project will contribute towards more reliable assessment and management methods for cutting and embankments, in order to increase the resilience of transportation network.
It is all for today!
I hope it is clear enough and, as usual, any comment will be welcome!
Thank you for reading,
Chat to you soon!
Nino
