Resilience of geotechnical systems

Code:
SSD: ICAR/07

Learning outcomes: 

The resilience of any engineering system against extreme environmental events can be defined basing on four properties: robustness, redundancy, rapidity, and resourcefulness. Robustness refers to the strength of systems to withstand a given level of demand without suffering a loss of functionality. Redundancy indicates the presence of elements designed to fail without significant effects on the overall performance of the system. Rapidity is the capacity to recover the properties of the engineering system timely to contain losses. Resourcefulness is the capacity to identify damages, establish priorities, and mobilize resources for the interventions. 

Resilient based-design strategies of geotechnical systems (i. e. those made by soil or interacting with it) are aimed to improve their robustness and redundancy. Real-time monitoring systems can lead to a quick assessment of their performance after the occurrence of an extreme event, hence may improve the rapidity and the resourcefulness. 

The course firstly focuses on the key aspects of the performance of some geotechnical systems typically employed in road and railway infrastructures, such as embankments, retaining structures and foundations of viaduct piers, against extreme meteorological and seismic events. The technologies currently suitable to monitor their performance and the interventions to improve it will be illustrated and discussed with reference to robustness, redundancy, resourcefulness, and rapidity.

Contents: 

Engineering Resilience

• Definition: the concept of resilience applied to infrastructures; robustness, redundancy, rapidity and resourcefulness.
• Resilience assessment methods: system functionality function: basic concept; definition of intensity measures for extreme natural events and engineering demand parameters; fragility curves

Earth structures: embankments and slopes

• Construction: geometrical features of embankments and slope cuts; compaction, pre-loading and excavation procedures.
• Stability: mechanisms and kinematics of natural or artificial slope instability; role of pore pressure; Limit Equilibrium Methods of analysis.
• Performance and interventions: settlements due to self-weight and additional loads; effects on pavements; mitigation techniques.
• Monitoring: use of inclinometers and optical fibers; pore pressure measurements for stability; use of ground surface levelling and satellite surveys for settlements; monitoring of seismic or hydrological intensity measures to estimate the expected damage.

Retaining structures

• Construction: earth pressure: basic concepts; gravity structures (masonry or unreinforced concrete walls, r.c. cantilever walls); embedded structures (cast-in place cantilever walls, pre-cast bulkheads); anchors and props. 
• Stability: Rankine earth pressure theory; forces equilibrium-based solutions; role of pore pressures; mechanisms and kinematics of rigid and flexible wall ultimate states; Limit Equilibrium Methods of analysis.
• Performance and interventions: empirical and simplified methods for predicting settlements and horizontal displacements; effects on roads and railways; mitigation techniques.
• Monitoring: use of inclinometer and ground surface levelling surveys for horizontal and vertical displacements; monitoring of seismic or hydrological intensity measures to estimate the expected damage.

Foundations of viaduct piers: caissons and piles

• Construction: construction technologies of caisson and piles and their effect on the stress state mobilized in the soil.
• Stability: foundation bearing capacity under vertical or horizontal loads in drained and undrained conditions.
• Performance and interventions: displacements and rotations due to self-weight and additional loads; effects on the viaduct; mitigation techniques.
• Monitoring: use of strain gauges or optical fibers in piles, monitoring of seismic intensity measures to estimate the expected damage.

Teaching method: Frontal lessons, in-class exercises

Teaching material: 

Slides of the lessons, journal papers, books

Examination procedures: 

Discussion on one or more in-class exercises and on the theoretical and technical aspects debated within the course