2. What is "Safe-Earth"?

Welcome back to my blog!

Today I would like to tell you more information about my project which I am currently working on.

Embankment

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.

Example of cutting failure

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.

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. 

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. 

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