FCE 311 Geotechnical engineering

• Soil


  Relatively loose mass of mineral and organic materials and sediments found above the bedrock, which can be relatively easily broken down into its constituent mineral or organic particles

  
• Soil consists of layers of minerals constituents of variable thickness, which differ from the parent materials in the morphological, physical, chemical and mineralogical characteristics

  
• Soil


  A natural product of weathering of rocks and decomposition of organic matter
• Soil is made up of mineral particles (clay, silt, sand) and organic matter (humus).
• Soil is composed of mineral particles (clay minerals, quartz, feldspar) and organic matter.
• Sand has particle sizes between 0.2 mm to 1.75 mm.
• Cohesion refers to the attraction between clay particles due to electrostatic forces.
• Clay Minerology
• Types of soil structures
• Factors affecting soil structure
• Importance of understanding soil structure
• Classification of soils based on their structure
• Particle size distribution curves
• Soil classification systems (e.g., AASHTO, USCS)
• Compaction characteristics of soils
• The degree of compaction depends on factors such as moisture content, type of equipment, and compaction energy.
• Compacted soil can be used as construction material or fill material.
• Laboratory tests are used to determine the compaction properties of soil samples.
• Standard Proctor test is commonly used to evaluate the compaction characteristics of soils.
• In situ testing methods include standard penetration test (SPT), cone penetration index (CPI) test, vane shear test, plate load test, dynamic penetrometer test, and light-weight deflectometer test.
• Standard Proctor test is commonly used to evaluate the maximum dry density and optimum moisture content of compacted soil.
• Modified Proctor test is similar to Standard Proctor but uses different compaction energies.
• Cone penetrometer testing (CPT) involves pushing a cone into the ground at a constant rate while measuring the force required to push it further.
• Dynamic cone penetration test (DCP) measures the resistance of soil layers to penetration by a cone-shaped probe.
• AASHTO system classifies soils into six groups based on their plasticity index and liquid limit.
• Soil classification systems based on grain size distribution include AASHTO, Unified Soil Classification System (USCS), and International Society of Soil Mechanics and Foundation Engineering (ISSMFE).
• Optimum Moisture Content (OMC): The moisture content that produces the highest possible dry density when using a given amount of compactive effort.
• Moment diagram
• Honeycomb structure of soils and flocculation
• Atterberg limits
• Liquid Limit (LL) - The water content at which soil changes from semi-solid to fluid consistency.
• Plastic Limit (PL) - The water content at which soil changes from plastic to semisolid consistency.
• Shrinkage Limit (SL) - The water content below which further loss of water causes volume change but no appreciable decrease in strength or stiffness.
• Shrinkage limit (SL) - The minimum water content below which further loss of water does not cause any volume change.
• Plastic limit (PL) - The water content below which a soil is plastic or non-flowing and above which it flows like a liquid.
• Consistency index (CI) = LL – PL
• Consolidated undrained triaxial test
• Shrinkage limit (SL) - The minimum water content at which a soil can lose additional water without shrinking in volume.
• Effective stress is defined as the difference between total stress and pore pressure, while effective strain is the deformation caused by the applied load on the material.
• Activity Index (AI) = PI – SL