Foundations II

Soil Mechanics.

In Theoretical-Practical classes, the expository and inquisitive method is used to explain the theoretical subjects and there will be individual and group resolution of exercises. Students must carry out an individual slope stability project using specialized software and a laboratory compaction test carried out by groups of 2/3 students. In tutorial classes, the methodology is based on competencies. The application of the software is trained and the students are monitored by clarifying doubts, solving exercises and guiding practical work. Study visits will be carried out when possible. In the Laboratory Practice classes, students perform tests working as a team, and watch demonstrations on reduced percolation models in soils.

Technology and design of geotechnical structures involving earth works, including two-dimensional seepage, slope
stability, compaction, soil reinforced and geosynthetics. Specific Skills: Analyze and design natural and excavation slopes and embankments, compaction situations, soil reinforcement and geosynthetic usage. Recognize, diagnose and prevent pathologies in earth works. Use software programs to evaluate stability and safety of geotechnical structures.

1. Two-dimensional seepage in soils. Basic principles and theories (Revisions). Permeability and Darcy’s law (Revision). Hydraulic head. Bernoulli theorem. One-dimensional ascending and descending seepage. Influence of seepage in water pressures and soil effective stresses. Equivalent permeability coefficient in stratified soil massifs. Two-dimensional seepage. Flow nets in soil with permeability isotropy. Flow mathematical equation. Flow evaluation. Soil stress state evaluation. Flow nets in soil with permeability anisotropy. Hydraulic instability and collapse. Critical gradient. Piping and hydraulic heaving.
2. Slope stability. Types of slopes. Natural, excavation and constructed. Geomorphological evolution of slopes. Erosion. Land movements. Geological influence on slope stability. Lithology. Fractures and joints. Hydro-geological conditions. Causes of slope unstabilization. External and internal causes. Stabilization works. Stability analysis methods. Infinite slopes: dry frictional soil with seepage parallel to ground surface; cohesive soil. Safety evaluation according to Eurocode 7. Circular slipping surfaces. Failure mechanism. Total stress analysis. Partially submerged slopes. Taylor’s stability number. Slices methods. Fellenius. Bishop. Bishop and Morgenstern stability numbers. Stability of embankment and unsupported excavation in clays. Embankments in soft soils.
3. Compaction. Compaction energy. Compaction curves. Compaction of non cohesive soils. Compaction of cohesive soils. Compaction test. Proctor. Procedures and results.  Types of compaction. Pressure, impact and vibration. Compaction works and equipments. Precautions. Selection of the adequate equipment. Compaction control in the field. Tests. Frequency.
4. Soil reinforcement. Reinforced earth. General characteristics. Basic principles and assumed behaviour. Design. Materials. Constructive procedures. Geosynthetics. Main types. Functions and characteristics of the materials. Design properties. Walls and slopes reinforced with geosynthetics. Design and constructive details.

NAO

Elements provided by the teacher.