Università Roma Tre

EXCAVATIONS AND UNDERGROUND CONSTRUCTIONS

1 – Elements of soil mechanics
• Total stress and effective stress, stress path of soil elements.
• Permeability, drained and undrained conditions.
• Stress-strain behaviour of typical soil elements.
• Deformability and strength properties of soils.

2 – Elements of rock mechanics
• Basic concepts of rock material and rock mass, discontinuity (joints, faults).
• Survey and representation of orientation and spacing of discontinuities.
• Mechanical properties of rock materials and discontinuities.
• Quality index and classification systems for the rock mass (particularly, GSI)
• Deformability, strength and permeability of the rock mass.

3 – Excavation methods and support systems for underground structures
• Different types of underground excavations: shallow and deep tunnels, cavern and adits.
• Excavation methods: “cut and cover” and “blind face” excavation.
• “Drill and blast” and “Mechanized excavation”, typical support systems.
• Tunnel Boring Machine (TBM) for rock tunnels.
• “Earth Pressure Balance” and “Slurry Shield” machines for soil tunnels.
• Consolidation works by grouting and ground freezing.

4 – Geotechnical design of slopes and shallow excavations
• Stability analysis of cut and natural slopes.
• Limit equilibrium methods: plane wedges and slices methods.
• Short- and long-term conditions, influence of pore pressure and seismic actions.
• Design of sheet pile walls for cut and cover tunnels.

5 – Geotechnical design of deep tunnels
• In situ stress conditions, influence of topografy and geological stress history.
• Stress and strain around the cross-section of a deep tunnel (plane conditions)
• Stress and strain near the face of the tunnel (three-dimensional conditions)
• Excavation of a tunnel beneath the water table
• Analysis of stability: failure conditions for the face and for the tunnel cross-section.
• Analysis of ground-support interaction: convergence-confinement method
• Loads acting on tunnel support: lining systems for traditional excavation methods and mechanized excavation methods.
• Prediction of the settlement trough caused by tunnel excavation (empirical method) and assessment of possible damage.

Lecture notes prepared by the lecturer (static analysis for tunnels, construction methods for underground structures, slope stability, guidelines and national codes).
Further suggested readings from technical literature.